Download Putting the Treat into Treatment: Teaching Pet Owners to

Putting the Treat into Treatment:
Teaching Pet Owners to Get Pets from the
Living Room to the Exam Room in a Calm State
Mikkel Becker, CPDT
VetStreet.com
Seattle, WA
Walking tools that help owners gain control over their pet’s forward motion and direction without the use of force are front clip
harnesses and head halters. It’s important to use fixed length leashes and to avoid retractable leashes, especially with fearful animals,
as numerous problems are likely to occur with such tools and there’s a general lack of control.
Cat harness and leash can be used to teach kittens and relaxed adult cats to follow and have protected time outdoors. Such walking
devices also make the relationship more interactive and provide another form of control useful for minimal restraint during exam if the
animal is accustomed prior.
Teaching animals to relax in the car is another important way to reduce stress before the animal has even arrived. Decreasing the
anxiety of being in a crate, then reducing aspects of the car that might be stressful (such as noises and motion sickness) along with
Victory Visits to fun places can help reduce anxiety. For some animals simply training outside of the car or sitting in the car while
getting their meal, treats or doing training may be a helpful place to start.
Victory Visits are one way to practice elements of the veterinary visit that are made to be more like the actual vet visit while being
kept positive and at a rate the animal tolerates. Victory Visits are done in preparation for actual exam and treatment at the hospital and
are preventive in building up a positive association with the clinic. Puppy classes and kitten socialization guidance are other strategies
for building a more social, less aggressive and more handling tolerant animal from the start.
To get animals to move on or off of things or to approach something targeting, luring and tossing treats are all helpful strategies.
Treating is one helpful strategy for counter conditioning an animal to the veterinary experience. But, in many cases the treat rate is far
too low and the reward value or treats given is minimal for the animal. Rather than one to three harder treats given during the visit
have an arsenal of available treats, toys and other rewards to employ. And, employ the tastiest, most enjoyable treats possible at a fast
rate to keep the animal occupied during exam and procedures. One tactic is using distractions and feeding or keeping the animal’s
attention on something else throughout the procedure. Or, another useful strategy for decreasing anxiety longterm is conditioning the
animal to tolerate handling.
AAHA guidelines are helpful for incorporating behavior guidelines and checks into regular veterinary visits to address problems
early and often. The sooner a behavior issue is addressed the better chance it has for being resolved. Many issues get worse, not better,
when left on their own without treatment.
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Fear Free, Low-Stress HandlingUnderstanding the Art, Design, and Feel of this Fashion Tech Style
Jonathan Bloom, DVM
Willowdale Animal Hospital
Toronto, Ontario, Canada
Many pet owners fail to identify, and are reluctant to address, conditions such as dental disease and arthritis in their pet because they
don’t see the disease, and they don’t appreciate the negative impact that it has on the body. In contrast, most pet owners are EXPERT
at identifying fear and anxiety in their pets, and owners are very much aware of how a negative experience can impact both their pet’s
mental health and wellbeing. Experience and careful observation reveal that those sentiments are not restricted to just the outpatient
visit, but also apply and contribute to the pet owner’s reluctance to hospitalize their pet. In addition, pet owners are reluctant to
approve necessary routine procedures such as blood collection and x-ray for much the same reason. Implementing strategies to
maximize patient comfort is the most prudent way to create successful experiences while visiting the hospital. Pet owners visiting my
practice have been overwhelmingly accepting and appreciative of the efforts made to ease their pet’s fear and anxiety.
Technicians have been performing common procedures such as blood draws, nail trims, and x-rays the same way for decades. But
just because it has become the norm, doesn’t mean that staff like it! No staff member likes being bitten by a dog, or scratched by a
cat. No staff member loves donning protective leather gloves to hold a cat for a nail trim or to remove an IV. No staff member loves
stretching pets out in an unnatural and uncomfortable position to take an x-ray. And no staff member loves working in an
environment with barking and whining pets. We all work very hard and want to be appreciated for what we do. It is much more
rewarding when pets can be gently controlled for nail trims and IV placements, when pets can be calmly positioned for x-rays, and
when the background noise from the dog wards can be kept to a minimum.
Identifying fear and anxiety in the hospitalized pet
A problem well stated is a problem half solved! Proper care for out-patient procedures and for hospitalized pets start with the proper
identification of fear and anxiety. Veterinary healthcare providers need to pay more attention to signs such as trembling, hiding under
bedding, vocalizing, body position, and lack of comfort behaviours etc.
The pet’s surroundings and housing
Common belief has long been that dogs are colour blind. Dogs can however see many of the same colours that humans can see. Fear
Free™ has developed a colour palette that was selected to be both positive and visually comfortable. Bright lighting can also be
uncomfortable for pets. Dimmable lights are ideal. Cages are believed to best suited for housing when there is opportunity for
looking outward with few obstructions, or have the option to retract to an area when less sensory stimulation is present is also ideal.
This can be achieved by providing boxes, tents, or partial covers so pets can choose their level of stimulation.
Sample collection
Attention should be paid to commonly performed procedures such as blood collection, urine collection, IV catheter placement and
removal, treatment of skin wounds etc. Procedures used to make these more comfortable experiences often include the use of
compression wraps, topical anesthetics such as Emla cream, pharmaceuticals, and environmental control.
Radiology
For years, pets have been forced into dark X-ray rooms, stretched out onto hard table tops, placed on their backs with their legs being
squeezed by the vice like grip of lead lined gloves, while their limbs are pulled in 4 different directions. There is nothing natural or
enjoyable about this for pets. Retakes are numerous, and X-rays are often of compromised quality. Several options including
compression wraps, pinch induced behavioural inhibition, or pharmaceuticals are often used to create faster, better quality, more
comfortable x-ray experiences for pets.
Post-operative care
Pets often experience stress and anxiety due to the direct result of pain. Careful attention must be paid to regularly assessing and
addressing pain relief in our hospitalized pets. Environmental control is also critical in ensuring a smooth, comfortable post-op
recovery including consideration given to noise levels, music, pheromones, body positioning etc.
My staff have never been more eager to accept a fresh and innovative healthcare initiative in the past as they have been for FEAR
FREE™. They realized that they are surrounded by calmer, happier, and more easily handled pets. As a result, staff are working in a
more safe and in a more enjoyable work space. Subsequently, staff satisfaction and staff morale have never been higher. The creation
of a Fear Free™ philosophy and culture benefits pets, pet owners, hospital staff, pet healthcare, and the business as a whole.
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Thyroid Disease in Dogs and Cats
David Bruyette, DVM, DACVIM
VCA West Los Angeles Animal Hospital
Los Angeles, CA
Hyperadrenocorticism in cats
Hyperadrenocorticism develops most commonly in middle-aged to older cats (mean age = 10.4 years; range 6 - 15 years). Of the
reported cases of feline Cushing's syndrome (78%) have been females. This female sex predilection resembles the human syndrome
and contrasts with canine hyperadrenocorticism, where no sex predilection occurs.
The most common historical findings and clinical signs associated with feline hyperadrenocorticism are polyuria, polydipsia, and
polyphagia. These signs likely correspond to the high incidence of concurrent diabetes mellitus (76%) found in cats with
hyperadrenocorticism, and are consistent with the lack of overt signs preceding marked glucose intolerance observed in
experimentally-induced disease. The typical "Cushingoid" pot-bellied appearance with hepatomegaly, weight gain, and generalized
muscle wasting is common in cats as in dogs. Dermatologic abnormalities frequently recognized include an unkempt hair coat with
patchy alopecia, and very thin skin prone to traumatically induced tears and secondary infections.
Hyperglycemia is the most common laboratory abnormality found on serum biochemistries. Cats appear more sensitive to the
diabetogenic effects of glucocorticoid excess than dogs. Cats with concurrent diabetes mellitus often exhibit cortisol-induced insulin
resistance, requiring high daily doses of insulin to control their hyperglycemia and glucosuria. Hypercholesterolemia is also common,
and may relate to insulin resistance and increased lipolysis. Cats lack the steroid-induced isoenzyme of alkaline phosphatase found in
the canine, and the half-life of the enzyme appears to be significantly shorter in the cat. Elevation of serum alkaline phosphatase
(SAP) is present in only approximately one-third of cats compared to nearly 90% of dogs with hyperadrenocorticism. Increases in
SAP and the hepatocellular enzyme ALT appear to correspond with the regulation of the diabetic state, rather than representing direct
indicators of glucocorticoid excess. These enzymes frequently normalize with adequate regulation of diabetes, even without therapy
directed towards the hyperadrenocorticism. Hematologic findings associated with hypercortisolemia (lymphopenia, eosinopenia, and
neutrophilic leukocytosis) occur inconsistently in feline hyperadrenocorticism. Despite clinical polyuria and polydipsia, cats appear to
maintain urine specific gravities of greater than 1.020 more frequently than dogs, and only occasionally exhibit dilute urine and
decreased blood urea nitrogen concentrations commonly seen in dogs with hyperadrenocorticism.
Endocrinologic evaluation of cats suspected of hyperadrenocorticism involves screening tests to confirm the diagnosis, and
differentiating tests to distinguish pituitary-dependent disease (PDH) from adrenal tumors (AT). Adrenocorticotropin (ACTH)
stimulation testing in adrenocortical hyperfunction is not as definitive as for hypoadrenocorticism. Fifteen to 30% of cats with
confirmed hyperadrenocorticism have had normal cortisol response to ACTH administration (false negatives). In addition, stressed
cats and those with non-adrenal illnesses may show an exaggerated response to ACTH in the absence of hyperadrenocorticism (false
positives). A normal urine cortisol-to-creatinine ratio (UCCR) can be used to exclude the diagnosis of hyperadrenocorticism in cats as
described in dogs. The UCCR is attractive due to the ease of sampling compared to other endocrine function tests, but is non-specific
and will be elevated in a variety on non-adrenal illnesses. An exaggerated ACTH stimulation test or an elevated UCCR should be
pursued with suppression testing prior to initiating any therapy.
Normal cats are more variable than dogs with respect to the degree and duration of adrenocortical suppression following
dexamethasone administration. Intravenous doses of dexamethasone that have been evaluated in the cat range from 0.005 to 1.0
milligrams per kilogram. A dosage of 0.01 mg/kg of dexamethasone, commonly used in low-dose dexamethasone suppression testing
in dogs, led to a significant drop in serum cortisol levels in ten normal cats, but 2 of the cats showed a slight escape from suppression
by 8 hours after injection. Intravenous dexamethasone sodium phosphate (DSP), 0.01 and 0.1 mg/kg, produced equivalent reductions
of plasma cortisol levels, but suppression was sustained below baseline longer with the higher dosage. Cats with various non-adrenal
illnesses have also shown inadequate cortisol suppression after a low-dose (0.01 mg/kg) of DSP. The 0.1 mg/kg dosage of
dexamethasone seems to more reliably suppress cortisol levels in normal cats and cats with non-adrenal illnesses. Elevated cortisol
levels eight hours post-dexamethasone injection, using the 0.1 mg/kg dosage, appears to be a sensitive a diagnostic test for feline
hyperadrenocorticism (89%) similar to the low-dose (0.01 mg/kg) screening test in the dog.
The combined dexamethasone suppression/ACTH stimulation test has been used successfully to diagnose hyperadrenocorticism in
the cat. Affected cats display inadequate suppression of cortisol 2-4 hours after an injection of 0.1 mg/kg of dexamethasone, and an
exaggerated response 1-2 hours after ACTH stimulation. The ability of the combined test to discriminate PDH from AT is unclear.
Several cats with confirmed pituitary disease failed to suppress 2-4 hours after dexamethasone. Extending the duration of postdexamethasone monitoring, or using higher doses of DSP may improve the ability of the combined test to distinguish PDH from AT.
Currently, the combined test does not appear to offer more clinical utility than either the ACTH stimulation or dexamethasone
suppression test evaluated separately.
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An ultra-high dose, 1.0 mg/kg, dexamethasone suppression test has been used to distinguish PDH from AT in the cat. Two cats
with hyperadrenocorticism diagnosed by the combined high dose dexamethasone suppression/ ACTH stimulation test had exaggerated
responses to ACTH with no cortisol suppression 2-4 hours after 0.1 mg/kg DSP. These cats did suppress following the ultra-high dose
of dexamethasone, and were later confirmed to have PDH. Cortisol levels should be monitored at several time points following
dexamethasone administration to determine if any suppression (a 50% or greater reduction in pre-test values) is occurring. Cats with
PDH may show suppression 2, 4, or 6 hours into the test only to escape from the suppressive effects of dexamethasone by 8 hours.
One cat with an adrenal adenoma failed to suppress following dexamethasone doses ranging from 0.1 to 1.0 mg/kg. As is the case in
dogs, suppression following high doses of dexamethasone is diagnostic for PDH, but failure to suppress requires further testing to
distinguish pituitary from adrenal disease.
Determination of plasma ACTH concentrations is an effective way of diagnosing PDH. The normal range of plasma ACTH is
lower in cats than in dogs, and many normal cats may have concentrations of ACTH below the lower limits of the sensitivity of the
assay. Cats with PDH will have normal to elevated ACTH concentrations while cats with adrenocortical adenomas or carcinomas will
have undetectable plasma ACTH levels. Plasma ACTH samples need to be collected and handled carefully. Veterinarians should
consult their diagnostic laboratory for specific instructions prior to performing the test. Incorrect sample handling can falsely lower
measured values. Normal to elevated plasma ACTH levels support a diagnosis of PDH, whereas low concentrations may require
additional diagnostic testing. As in the differentiation of canine hyperadrenocorticism, ACTH levels should only be used to
distinguish PDH from AT after hyperadrenocorticism has been confirmed by other screening diagnostics.
Pituitary-adrenal function tests need to be interpreted in conjunction with historical, clinical, and clinicopathologic findings before
any conclusions can be drawn. No single diagnostic test is infallible. Equivocal results or discordant findings should be reevaluated.
Hyperadrenocorticism is an uncommon disorder in cats. Consequently, false positive test results should be anticipated. Interpretation
of endocrinologic testing should incorporate all available information before any therapeutic intervention is attempted.
Diagnostic imaging can facilitate differentiation of PDH from AT when screening tests and clinical findings suggest
hyperadrenocorticism. Approximately half of canine adrenal tumors are mineralized and can be recognized radiographically. The
frequency of mineralization in feline adrenocortical tumors is unknown, but up to 30% of normal cats may have calcification of their
adrenal glands. Abdominal radiographic findings in cats with hyperadrenocorticism included hepatomegaly (69%) and obesity.
Ultrasonographic evaluation of adrenal size and morphology has been described for dogs and cats. Nonfunctional adrenal tumors can
be incidental findings in humans undergoing abdominal imaging. The incidence of "silent" adrenal masses in the cat is unknown. The
presence of unilateral adrenomegaly or distortion of adrenal architecture in a cat suspected of hyperadrenocorticism is strong evidence
of AT. Abdominal computerized tomography (CT) and magnetic resonance imaging (MRI) offer improved resolution for the
detection of adrenal tumors or hyperplasia. CT and MRI detection of pituitary masses is also now feasible for small animal patients.
Adrenal tumors accounted for 22% of the reported cases of feline hyperadrenocorticism. Half of the adrenocortical tumors were
found histologically to be adenomas and half carcinomas. The treatment of choice for adrenal tumors is surgical adrenalectomy. Two
cats with adrenocortical adenomas responded well to unilateral adrenalectomy, with clinical signs resolving over 4 to 8 weeks. One
cat with an adrenal adenoma removed surgically developed a recurrence of signs 12 months postoperatively. An adenoma of the
contralateral adrenal gland was diagnosed. The cat survived a second adrenalectomy and was disease-free for over two years
following the second procedure. Surgical therapy and long term follow-up for adrenocortical carcinomas in cats has not been
reported.
Treatment options for pituitary dependent hyperadrenocorticism in the cat include both surgical and medical alternatives. Bilateral
adrenalectomy followed by mineralocorticoid and glucocorticoid replacement therapy was performed in 11 cats. Nine cats responded
well to surgery with cessation of polyuria and polydipsia, regrowth of hair coat, and marked improvement (4) or resolution (5) of
diabetes mellitus. One cat developed acute signs of circling, wandering aimlessly, and apparent blindness 2 months post-operatively.
An expanding pituitary tumor was suspected, but no necropsy was performed. Two cats died within one week of surgery from sepsis.
Survival times for 6 cats with adequate follow-up after bilateral adrenalectomy for PDH ranged from 1 to 12+ months (median 5
months). Two cats are still alive, one year post-operatively. These results suggest that surgical complications of bilateral
adrenalectomy may be less frequent in cats than in dogs.
Surgical treatment can also include transsphenoidal hypophysectomy which is performed at WLA for cats with pituitary masses
extending above the sella (macroadenoma). Cats with functional tumors have similar success rates to those reported in dogs with
PDH.
Four drugs (ketoconazole, mitotane, metyrapone and trilostane ) have been investigated for the medical management of
spontaneous feline hyperadrenocorticism. Ketoconazole, an antifungal imidazole derivative, has been shown to inhibit adrenal and
gonadal steroidogenesis in humans and dogs. One month of ketoconazole (15mg/kg orally twice daily) administration in 4 cats did not
significantly reduce baseline plasma cortisol or ACTH responsiveness at doses 3 times greater than those effective in dogs. Two of 4
cats treated with 10 - 20 mg/kg/day of ketoconazole had adequate control of hypercortisolemia. One of the 4 cats developed severe
thrombocytopenia after only one week of therapy and had to discontinue the medication. A cat with adrenocortical adenocarcinoma
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treated with 30 mg/kg/day for 3½ months showed improved regulation of diabetes and reduction in pu/pd despite no improvement in
hyperresponsiveness to ACTH. The cat ultimately was euthanatized subsequent to a non-healing skin laceration, chronic infections,
and worsening insulin resistance. No evidence of hepatotoxicity or thrombocytopenia was seen at the 30 mg/kg/day dosage of
ketoconazole, but the effectiveness and safety of this therapy remains questionable.
Mitotane, o,p'-DDD, is an adrenal cytotoxic agent and has been used successfully to treat dogs with PDH and AT. Use of mitotane
in cats has been discouraged due to the feline sensitivity to chlorinated hydrocarbons. Three of 4 normal cats treated with o,p'-DDD at
dosages ranging from 25 - 50 mg/kg, divided twice a day, tolerated the drug well, and remained clinically normal throughout
treatment with mitotane. Only 2 of the 4 cats showed a decreased responsiveness to ACTH with mitotane. The cat with the largest
reduction in post-ACTH cortisol levels developed vomiting, diarrhea, and partial anorexia lasting 2 weeks after a 50 mg/kg dosage of
mitotane. Two cats with PDH treated with o,p'-DDD (25 mg/kg/day x 25 days, and 25 - 50 mg/kg/day x 59 days) tolerated the drug
without apparent toxicity, but therapy was ineffective in controlling clinical signs in either cat. A cat with PDH treated with mitotane
(50 mg/kg/day x 1 week, then 50 mg/kg/week) developed signs compatible with iatrogenic hypoadrenocorticism after 40 weeks of
therapy with o,p'-DDD. At that time the cat was anorectic, lethargic, and exhibiting neurologic signs including mydriasis, pacing, and
head pressing. Computerized tomography revealed a large pituitary mass extending above the sella turcica. Mitotane was
discontinued, and the cat was treated with 60Co teletherapy. Subsequent CT examinations revealed shrinkage and then disappearance
of the mass 10 months post-irradiation. The cat was euthanatized for continued diabetes mellitus and post-irradiation cataracts 2 years
after the initial diagnosis of hyperadrenocorticism. We have had 3 other cases where a positive response to mitotane was observed
clinically.
Metyrapone, an inhibitor of the 11-b-hydroxylase enzyme that converts 11-deoxycortisol to cortisol, has been used effectively in
man to reduce the clinical signs of hypercortisolemia. A reciprocal rise in plasma ACTH levels occurs with falling cortisol
concentrations and can eventually override the enzymatic block, allowing a return of clinical signs. In humans, metyrapone is utilized
as an adjunctive therapy with pituitary irradiation or surgery. Dosages ranging from 195 - 250 mg/day have been used in cats with
hyperadrenocorticism without observed toxicity. In a recent report, a diabetic cat with PDH and severe nonhealing skin wounds was
treated with 65 mg of metyrapone orally 3 times a day. After 2 days of therapy the cat developed signs of glucocorticoid deficiency
including depression, tremors, and ataxia. The cat improved rapidly following treatment with injectable steroids, and was discharged
on twice daily metyrapone therapy. Cortisol response to exogenous ACTH was absent when evaluated on day 7. The cat was reexamined 24 days later after a hypoglycemic episode. The cats skin wounds had resolved and hair regrowth was evident. A follow-up
ACTH stimulation test revealed a slightly exaggerated response. The cat underwent successful bilateral adrenalectomy and was
euglycemic, with a normal haircoat, 4 months post-operatively. Two of 3 other cats reported in the literature also showed clinical
improvement with metyrapone therapy, but follow-up periods were short (less than 6 months). Whether longterm therapy with
metyrapone can control hypercortisolemia in cats, or whether rising ACTH levels eventually overwhelm enzymatic blockade has not
been determined. Metyrapone appears to permit rapid correction of hyperadrenocorticism in some cats, and may be useful for presurgical stabilization prior to adrenalectomy.
We have recently evaluated the safety and efficacy of trilostane therapy (Vetoryl, Dechra Pharmaceuticals) in 15 cats with PDH.
Clinical signs (13 of 15 cats) and ACTH stimulation testing results (13 of 15) improved with trilostane therapy. Diabetes mellitus was
reported in 9/15 cases. Insulin requirements decreased by 36% within 2 months in 6/9 diabetic cats. Median survival time was
617 days for all cats (range 80-1,278 days). Complications included weight loss, urinary tract infections, chronic kidney disease,
seizures, and recurrent pancreatitis. Hypocortisolemia was documented in 1 case. Cause of death occurred as a result of non-adrenal or
non-diabetic illnesses (renal failure, seizures [caused by hypoglycemia or unknown]), or lymphoma. Trilostane ameliorates clinical
signs of HAC in cats, is tolerated well in the long term, and can lead to improved regulation of diabetes. It should be considered first
line therapy for cats undergoing medical management of PDH.
Hyperadrenocorticism in dogs
A. Pituitary-dependent hyperadrenocorticism
1. Surgical management
i. Bilateral adrenalectomy
1. Technically difficult
2. Poor surgical/anesthetic risk
3. Permanently hypoadrenal and require lifelong replacement therapy
B. Hypophysectomy
1. See discussion at the end of this section
2. Lifelong therapy with thyroid hormone and prednisone necessary.
3. Medical therapy
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Trilostane therapy of canine hyperadrenocorticism
The efficacy and safety of trilostane in the treatment of canine PDH were evaluated in a multicentre study at the Royal Veterinary
College in London, the Veterinary Teaching Hospital in Dublin and Small Animal Hospital in Glasgow. Seventy-eight dogs with
confirmed PDH were treated with trilostane for up to 3 years. The starting dose varied from 1.8 to 20 mg/kg (mean = 5.9 mg/kg).
Trilostane appeared to be well tolerated by almost all dogs with only 2 dogs developing signs and biochemical evidence of
hypoadrenocorticism. One of these dogs recovered with appropriate therapy. The other died despite withdrawal of trilostane and
administration of appropriate therapy. A further two dogs died within one week of starting trilostane but in neither case could a direct
link with the trilostane therapy be established. The low prevalence of side effects compared favourably to those reported with
mitotane.
Trilostane was found to be nearly as effective as mitotane in resolving the signs of hyperadrenocorticsm. Polyuria, polydipsia and
polyphagia had dissipated in 40 dogs within 3 weeks after starting trilostane. Within 2 months, a further 20 dogs showed decreases in
their water and food consumption. These improvements were maintained as long as the dogs remained on adequate doses of trilostane.
Skin changes resolved in 24 out of 39 (62%) of dogs that initially presented with dermatological signs. All of these improvements
were maintained as long as the dogs remained on adequate doses of trilostane. Only 8 dogs that were treated with trilostane for more
than 2 months showed poor control of clinical signs. In contrast, mitotane is effective in about 80% of cases of pituitary dependent
hyperadrenocorticism (PDH).
Trilostane caused a significant (p<0.001) reduction in both the mean basal and post-ACTH stimulation cortisol concentrations after
10 days of treatment. The post ACTH cortisol concentration decreased to less than 250 nmol/l (9 µg/dl) in 81% of dogs within one
month and in another 15% at some time whilst on treatment. These improvements were also maintained in the study population for the
duration of the trial.
Thirty-five dogs had at least one dose adjustment over the treatment period. The dose was increased in 23 dogs up to four times the
starting dose. In one dog the dose was increased nine fold over a period of six months. The dose was decreased in nine dogs to as low
as a quarter of the starting dose.
The mean survival of all trilostane treated dogs was 661 days. Direct comparison with mitotane was difficult as 65% of the dogs
were still alive at the time of censor and therefore the mean survival may still increase.By comparison, the mean survival of mitotane
treated dogs has been reported to be 810 to 900 days.
Dosage and administration
The current suggested initial starting dose range for dogs with PDH is 1-2 mg/kg once daily. This needs to be adjusted according to
clinical signs and serum cortisol values (see below). Doses up to 40-50 mg/kg (divided twice daily) have been given with no
unwanted side effects. In some dogs twice daily dosing may be necessary. The drug is given with food.
Transsphenoidal hypophysectomy
A variety of treatments are available for PDH. Medical treatment options include drugs that chemically destroy the adrenals
(lysodren or op-DDD) inhibit enzymes in the adrenal leading to the synthesis of cortisol (ketoconazole, trilostane) or inhibit the
release of ACTH from the pituitary gland (Anipryl or selegiline). While these treatments can improve the clinical signs in 40-80% of
patients they need to be chronically administered, necessitate frequent monitoring and do not cure or address the primary cause of the
disease (the pituitary tumor). In humans, surgery to remove the tumor is the most successful long-term therapy. The most common
approach used is the transsphenoidal method, in which a passage way is made in the sphenoid sinus, an air space behind the back of
the nose, which is just below the pituitary gland. Surgical cure rates for PDH are reported to be in the range of 65-85%, although more
recent long-term follow up data suggest that the recurrence rate is as high as 25 % within 5 years. When no discrete adenoma can be
identified, remission of hypercortisolism is observed in only about 40%. Surgery has also been used to treat PDH in dogs. Several
groups, most notably in the Netherlands have performed these surgeries with success rates paralleling those reported for humans.
However, these surgeries have generally not been performed in the US. Veterinarians at VCAWLAAH, in collaboration with human
neurosurgeons that regularly perform transsphenoidal surgery in humans have developed the methods to perform these surgeries in the
US and are conducting a research study to determine how effectively these surgeries can be performed.
Hypoadrenocorticism
Primary hypoadrenocorticism has been described in cats. Addisonian cats are middle-aged, with a median age of 4 years (mean 5.8
+/- 3.7 years) and range in age from 1.5 to 14 years. No sex or breed predilection is seen. The most common historical problems
include lethargy, anorexia, and weight loss. Unlike dogs with adrenal insufficiency, diarrhea is not noted in Addisonian cats. Forty
percent of cats have histories of episodic vomiting. Similar to hypoadrenocorticism in the canine, cats often have a waxing and
waning clinical course, including temporary "remissions" associated with parenteral fluid and/or corticosteroid administration.
The most common findings on physical examination include depression, weakness, and mild to severe dehydration. Up to 40%
present with in severe shock with weak pulses, slow capillary refill times, and extreme weakness or collapse. The duration of clinical
signs preceding the diagnosis of hypoadrenocorticism ranges from 5 to 100 days, with a median of 14 days.
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Clinicopathologic findings in cats with primary hypoadrenocorticism parallel the patterns seen in the dog. Serum electrolyte
changes characteristic of mineralocorticoid deficiency are seen in most cats. Serum sodium:potassium ratios are less than 24 (range
17.9-23.7) with hyponatremia, hypochloremia, and hyperkalemia. All cats have had mild to severe azotemia (blood urea nitrogen 3180 mg/dl, normal range 5-30 mg/dl; creatinine 1.6-6.0 mg/dl, normal range 0.5-1.5 mg/dl), and hyperphosphatemia (inorganic
phosphorus 6.1-9.1 mg/dl; normal range 3.0-6.0 mg/dl). Hypercalcemia has been noted in one cat. Despite signs of dehydration and
prerenal azotemia, urine specific gravity was greater than 1.030 in only 40% of cats. The loss of renal medullary solutes, particularly
sodium, is believed to result in impaired renal concentrating ability. Distinguishing hypoadrenocorticism from acute or chronic renal
failure is critical to establishing an appropriate prognosis for clients.
Long-term management of cats with primary hypoadrenocorticism requires lifetime mineralocorticoid and glucocorticoid
supplementation. Oral fludrocortisone acetate (0.1 mg/day) or intramuscular injections of desoxycorticosterone pivalate (DOCP; 10 12.5 mg/month) have been successful in maintaining Addisonian cats. The dose of mineralocorticoid is adjusted as needed based on
follow-up serum electrolyte concentrations monitored every one to two weeks during the initial maintenance period. Normal
electrolyte parameters 2 weeks following DOCP suggests adequate dosing, but does not provide information concerning the duration
of action of each injection. Eighty percent of dogs require DOCP more frequently than every 30 days (5% need to receive DOCP
every 3 weeks), so frequent sampling during the early management period is recommended. Prednisone, 1.25 mg orally once a day, or
intramuscular methylprednisolone acetate, 10 mg once a month, can be used to provide adequate long term glucocorticoid
supplementation. Cats surviving the initial adrenal crisis can be managed successfully for many years. 60% of cats diagnosed with
primary hypoadrenocorticism are alive a median of 2.75 years after diagnosis. With appropriate glucocorticoid and mineralocorticoid
supplementation, cats with adrenocortical insufficiency should have a normal life expectancy.
Primary hyperaldosteronism
Feline primary hyperaldosteronism is diagnosed based on clinical signs, serum biochemistry, plasma aldosterone concentration,
adrenal imaging and histopathology of adrenal tissue. Cats may present with blindness caused by systemic hypertension. Many will
also present with weakness resulting from hypokalaemic polymyopathy. Elevated concentrations of plasma aldosterone and
adrenocortical neoplasia have been documented in all cases. Seven cases had adrenal adenomas (unilateral in five and bilateral in two)
and six had unilateral adrenal carcinomas. Three cases underwent medical treatment only with amlodipine, spironolactone and
potassium gluconate; two cases survived for 304and 984 days until they were euthanized because of chronic renal failure, while the
third case was euthanized at 50 days following failure of the owner tomedicate the cat. Ten cases underwent surgical adrenalectomy
following a successful stabilization period on medical management. Five cases remain alive atthe time of writing with follow-up
periods of between 240 and 1803 days. Three cases were euthanized during or immediately following surgery because ofsurgicalinduced hemorrhage. One cat was euthanized 14 days after surgery because of generalized sepsis, whilst the remaining cat was
euthanized 1045 days after surgery because of anorexia and the development of a cranial abdominal mass. It is recommended that
primary hyperaldosteronism should be considered as a differential diagnosis in middle-aged and older cats with hypokalaemic
polymyopathy and/or systemic hypertension and this disease should no longer be considered a rare condition.
In recent years, there has been renewed interest in primary hyperaldosteronism,particularly because of its possible role in the
progression of kidney disease.While most studies have concerned humans and experimental animal models, a recent paper highlighted
the occurrence of a spontaneous form of (non-tumorous) primary hyperaldosteronism in cats. At presentation, the main physical
features of 11 elderly cats were hypokalemic paroxysmal flaccid paresis and loss of vision due to retinal detachment with
hemorrhages. Primary hyperaldosteronism was diagnosed on the basis of plasma concentrations of aldosterone (PAC) and plasma
rennin activity (PRA), and the calculation of the PAC:PRA ratio. In all animals, PACs were at the upper end or higher than the
reference range. The PRAs were at the lower end of the reference range, and the PAC:PRA ratios exceeded the reference range.
Diagnostic imaging by ultrasonography and computed tomography revealed no or only very minor changes in the adrenals compatible
with nodular hyperplasia. Adrenal gland histopathology revealed extensive micronodular hyperplasia extending from zona
glomerulosa into the zona fasciculata and reticularis. In three cats, plasma urea and creatinine concentrations were normal when
hyperaldosteronism was diagnosed but thereafter increased to above the upper limit of the respective reference range. In the other
eight cats, urea and creatinine concentrations were raised at first examination and gradually further increased. Even in end-stage renal
insufficiency, there was a tendency to hypophosphatemia rather than to hyperphosphatemia. The histopathological changes in the
kidneys mimicked those of humans with hyperaldosteronism: hyaline arteriolar sclerosis, glomerular sclerosis, tubular atrophy and
interstitial fibrosis. The non-tumorous form of primary hyperaldosteronism in cats has many similarities with "idiopathic" primary
hyperaldosteronism in humans. The condition is associated with progressive renal disease, which may in part be due to the often
incompletely suppressed plasma renin activity.
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References
Mellet, AM, Bruyette D, Stanley S: Trilostane therapy for spontaneous hyperadrenocorticism in cats: 15 cases (2004-2013). J Vet Int Med 27: 1471-77,
2013.
Bisignano J, Bruyette D: Feline Hyperaldosteronism. J Vet Med 19: 76-87, 2012.
Mamelak A, Owen T, Bruyette D: Transsphenoidal surgery for pituitary adenomas using a high definition video telescope in dogs with Cushing’s
disease. Vet Surg Jan 27: 1532-1543, 2014.
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A Technician’s Role in Hydrotherapy
Debra Canapp, DVM, DACVSMR, CCRT, CVA
Veterinary Orthopedic and Sports Medicine Group
Annapolis Junction, MD
Hydrotherapy, either underwater treadmill or deep water therapy can be a valuable tool in veterinary rehabilitation. Similar to other
modalities in veterinary rehabilitation, it is important to understand its appropriate applications and limitations as well as proper
operation and maintenance in order to achieve the greatest benefits to both the patient and the practice.
This presentation will give the technician an overview of hydrotherapy, including its common applications, basic techniques, and
overview of equipment as well as general maintenance and tools used to best utilize its rehabilitation power. Specific conditions are
discussed as well as different examples of proper uses.
Applications
The most common indications for use of hydrotherapy include improving muscular strength, and improving range of motion in joints
with restrictions, conditioning, weight management and supporting return to function.
Both orthopedic and neurologic patients can benefit from earlier return to function with hydrotherapy. There are many cases and
parameters that would dictate either underwater treadmill or deep water therapy as being the preferred modality over the other.
Comparing the need for controlled weight bearing versus completely non weight bearing activity is the obvious distinction. After that
it may be as simple as the patient prefers one over the other or shows greater range of motion in one body of water as compared to the
other. Studies show that underwater treadmill activity in particular provides a reduced weight-bearing environment that enables
increased functional use of a limb without significant weight loading and resultant discomfort to a post-surgical joint. An additional
benefit is increased proprioceptive and tactile input provided by the viscosity of the water.
Many dogs that are unwilling to use a limb after injury or neurological dysfunction will use it in the water not only because of
increased comfort but also because of the resistance to forward motion in the functional limbs. This slows the gait pattern down
significantly, allowing them to focus on foot placement. This will help them use the limb to help maintain balance and stability. This
is particularly useful for dogs after femoral head ostectomy and neurological patients.
Most post-surgical and neurologic patients have a significant degree of muscle atrophy, muscle weakness and lack of tone. Muscle
atrophy and subsequently weakness also occurs secondary to osteoarthritis. Under water treadmill therapy can help these patients
improve in strength and mobility while deep water therapy can also provide comfort and resistance to help increase the tone of weak
muscles.
Injured joints often show reduced range of motion. Due to the hydrostatic pressure of the water and the direct correlation to
comfort, range of motion exercises can be performed with a greater degree of success in the water. Pain relief provided by warm water
facilitates muscle relaxation and tendon stretch in situations where contracture has occurred. Under water treadmill therapy provides a
correct but exaggerated gait pattern, particularly in flexion. Two common examples of this is the post-surgical cranial cruciate patient
with limited stifle flexion and post operative fragmented medial coronoid process with limited elbow flexion.
Athletes benefit in an underwater treadmill or deep water therapy both in muscle strengthening and cardiovascular endurance. This
is due to the increased resistance (viscosity) of the water. Buoyancy properties of water can aid overweight patients but decreasing
joint load and allowing them to exercise more safely in controlled environment. The buoyancy of the water reduces weight-bearing
stress on the joints while at the same time the resistance of the water increases metabolic demand and improves muscle strength.
Variables
Depth, speed, direction, and turbulence are the most common variables regulated by the technician in the underwater treadmill.
Temperature and turbulence are the most common variables regulated in deep water therapy.
Changing depth of the water in the underwater treadmill can significantly alter the joint range of motion and level of physical
exertion. Low water levels regulated to just above the carpus simulates 91% of weight-bearing. This water level increases carpal and
hock flexion more than any other level and is useful for patients with reduced flexion of these joints. Intermediate water levels at the
level of the elbow increases resistance with minimal buoyancy, simulating 85% of weight-bearing. This level is excellent for
conditioning athletes to build strength and endurance. Water levels at or just above the shoulder simulates 38% weight-bearing which
is primarily due to having a significant amount of the chest submerged. This water level provides maximum buoyancy for
strengthening the limbs with minimal load on the joints. Levels above this cause the canine to float and shorten their stride which can
reduce the benefit of this exercise.
Increasing speed increases exertion through turbulence and resistance. Slower speeds, 0.1-0.6 mph, are used primarily with patients
that have neurological problems. The viscosity of the water gives the patient more reaction time in order to try to properly place their
feet. Moderate speeds, 0.7- 2.0 mph, are used for most post surgical and arthritic patients. Faster speeds, 2.2-5.0 mph, are used for
athletes and for other stronger, more advanced patients. Most average sized dogs just starting on the underwater treadmill do best with
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initial speeds of 1.0-1.5 mph, which results in a comfortable, brisk walk. Allowing the patient to move at a brisk walk often cures
issues with attention and tracking well on the treadmill since it requires the patient to focus at the task at hand.
Increased turbulence through use of jets, either in the treadmill or deep water can simulate increased resistance. This increases the
exertion level, thus giving more intensity to the cardiovascular system and muscles.
Cold water and warm water have slightly different physiologic effects. Cold water tends to reduce heart rate, which can be
beneficial when exercising for conditioning. Most patients benefit from warm water 86F to 93F, since it has negligible effects on
cardio-respiratory parameters therefore minimizing exertion but provides the additional benefit of increasing circulation and
flexibility, thereby reducing discomfort. This applies for both underwater treadmill and deep water therapy.
Techniques
An experienced technician has a wide variety of techniques that can be used to the patient’s benefit in order to maximize their therapy
in the water. Placement of the technician in relationship to the patient can easily affect the attitude and focus of the patient. The
technician may encourage forward progress from the front, side or rear of the patient. The patient should be facing forward in the
underwater treadmill at all times for an even and therapeutic gait.
There are many ways the technician can aid a patient while they are on the underwater treadmill. Holding up a tail with slight
traction can aid a patient that tucks their pelvis losing stride in their rear limbs. When the buoyancy of the water is not enough to
maintain proper top-line and therefore proper biomechanics of foot fall there are several devices that can be applied to the patient. A
“Walk-a-Bout” can be attached by a nylon strap or a bungee cord to a bar that is supported by the tank. This assistance allows the
technician to work with the limbs without worrying about the patients’ balance. Balloons, foam, swim mitts or water wings can be
used under water to achieve increased flexion or resistance both in deep water and underwater treadmill. Toys and swim noodles can
be used to help guide the patient to an optimal workout. Swim noodles also can be used to increase the buoyancy of different parts of
the body to aid in gaiting or swimming.
Precautions
Some patients may show anxiety when first introduced to the water. This reaction can be minimized if time is taken to slowly
introduce them to the equipment and the water. Patients with cardiac or respiratory disease may experience more difficulty exercising
in water than on land, due to the viscosity and temperature of the water. Most of these patients can successfully exercise in the water if
properly monitored, managed and exercised conservatively.
Patients with newly sutured areas, significant dermal wounds or generalized infections, incontinent patients, or those with diarrhea
should not be engaging in water therapy until these conditions are resolved.
Conclusion
Underwater treadmill or deep water therapy can be extremely beneficial for patients with injuries, but can also improve quality of life
for patients with osteoarthritis and obesity. Additionally, it can be used for conditioning healthy canine athletes. The wide scope of
this modality can make it an advantageous addition to your practice.
References available on request
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How to Assist with Orthopedic Surgeries
Sherman Canapp, DVM, MS, CCRT, DACVS, DACVSMR
Veterinary Orthopedic and Sports Medicine Group
Annapolis Junction, MD
Preparation before surgery
As the veterinary technician, it is very crucial for the surgical assistant to know what the surgical plan is for the patient. Reading the
patient’s record, examination findings, and surgical plan prepared by the surgeon will help determine what instrumentation is needed
for the surgical case. Body weight and body condition score can help assist what size instruments and implants will be required for the
patient.
Radiographs
Obtaining radiographs both preoperatively and postoperatively is critical in orthopedics. Typically, two views are required for pre-op
and post-op radiographs.
Shoulder
Lateral view is taken in lateral recumbency with the affected shoulder on the table. The leg must be extended cranially and ventrally to
the sternum in order to avoid superimposition over the shoulder joint. The other forelimb is moved caudodorsally and the neck is
extended dorsally to rotate the sternum slightly. Caudocranial view is taken in dorsal recumbency with both forelegs extended
cranially. Special attention must be made to ensure the humerus is straight and parallel to the table as any rotation will result in an
oblique view of the shoulder joint.
Elbow
Lateral view is taken in lateral recumbency with the affected elbow on the table. The other forelimb is moved caudodorsally and the
neck is extended dorsally. Craniocaudal view is taken in sternal recumbency with the affected limb extended cranially. The patients
head is positioned away from the affected forelimb. It is important not to rotate the affected limb while positioning the patient’s head.
The radiograph should show the olecranon directly between the medial and lateral humeral epicondyles.
Stifle
Lateral view is taken in lateral recumbency with the affected limb on the table. The radiograph includes the stifle and tarsal joints. The
femoral condyles should be superimposed. Raising the tarsus assists in creating a lateral radiograph of the stifle. Caudocranial view is
taken in sternal recumbency with the affected limb pulled caudally in complete extension. Rotation of the limb should be prevented to
ensure the patella is centered between the femoral condyles. The tibial tuberosity should be centered as well.
Positioning
The procedure determines the positioning of the patient in the operating room. Shoulder procedures as well as hip procedures are
generally performed in lateral recumbency. Elbow scope procedures are generally in dorsal recumbency, while stifle surgeries can be
dorsal, lateral, or a combination of both recumbencies. It is important for the veterinary technician to know what procedure we are
performing in order to know how to position the patient, as well as the surgical tables and surgical equipment.
Draping in patient
Once the patient is positioned appropriately and the surgical area is prepped, the patient is ready to be draped in by the surgical scrub
assistant. Orthopedic surgeries are draped in using the hanging leg technique. The leg is hung with porous tape prior to prepping either
to a fluid ring stand or a hook that attaches to the ceiling. Once the assistant has scrubbed in, quarter drapes are placed around the most
proximal prepped area of the limb using Backhaus towel clamps. Then the limb is sterilely grabbed with a sterile field, leaving room
distally for an unsterile assistant to grab the tape close to the paw and cut the tape so that the leg is free for the scrub assistant to wrap.
The scrub assistant continues to wrap the foot of the leg, wrapping with the sterile field, adding a sterile glove, and finally a layer of
sterile Vetwrap. Once the distal end is wrapped the large patient drape can be applied by cutting a hole for the limb to pass through. It
is important to make sure the hole is not too large and exposes the quarter drapes below it. If the surgery involves an arthrotomy or an
open fixation, additional adhesive drape, such as Ioban, is applied.
Assisting during surgery
When scrubbed in and assisting the surgeon, the technician must know the difference between different actions and limb positions. In
orthopedics, understanding flexion, extension, distraction, drawer, abduction, adduction, pronation, supination is necessary to move
the limb of the patient properly. Knowing the steps of the procedure and the instruments used for each step is important in order for
the surgery to be performed efficiently. It is the assistant’s responsibility to anticipate and hand the appropriate instrument to the
surgeon. This means that the assistant must have the instrument ready and available moments before the surgical step occurs.
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Instrumentation
Suction
In orthopedics, a Frazier tip is predominantly used for procedures. The Frazier tip provides a pin point suction, covering a small
surface area. The Yankauer tip provides suction over a larger area and can remove large blood clots without clogging the suction tip. It
can be used in larger orthopedic surgeries, such as femoral head ostectectomies and total hip replacements.
Rongeurs
Rongeurs are instruments frequently issued in orthopedics to remove small amounts of bone. The tips of the rongeur are curved or
straight and the closing mechanism can either be single action or double action. Single action rongeurs are predominantly smaller, and
the larger rongeurs are double action. Double action rongeurs remove bone pieces with less force due to their double hinge.
Retractors
Retractors are used to improve visualization of the surgical field by deflecting tissue. There are two types of retractors: self-retaining
and hand-held. Hand-held retractors in orthopedics include the Senn, Hohmann, Army-Navy, and the Myerding. The Senn and ArmyNavy retractors have double-ends where both ends can be utilized for retraction. A Senn and Hohmann are used for retraction of small
surgical sites, like mini arthrotomies in stifle surgery, while the Army-Navy and Myerding retract larger amounts of tissue and
therefore used for deep, wider surgical sites, like hip surgeries. Self-retaining retractors in orthopedics include the Gelpi and the
Weitlaner. Both instruments include two moveable arms with a boxlock side bar to secure the retractor at a desired position. The Gelpi
retracts a smaller portion of tissue compared to the Weitlaner. They do not require an assistant to hold the instrument.
Periosteal elevators
These instruments are used to remove soft tissues, including periosteum, from the bone. This provides visualization of the bone for the
surgeon and also allows the surgeon apply implants directly to the bone for fixation. These instruments are available in a variety of
different shapes and sizes, with some being double-end and others single ended. Elevator types include the Freer, Sayre, AO-round
edge, and AO-edge.
Plates
Dynamic compression plates (DCP), locking compression plates (LCP), and limited contact dynamic compression plates are the most
common types of plates used in fracture repair. Dynamic compression plates are considered the primary bone plate system and is
made in 2.0, 2.7, 3.5, and 4.5mm sizes, named according to the screw size associated with the plate. Limited contact dynamic
compression plates are similar to DCPs, but instead have a scalloped underside to prevent as much direct compression as a DCP.
Locking compression plates also have scalloped undersides, but allows both dynamic and locking compression options.
Screws
Orthopedic screws have different designs, thread types, and arrangements depending on their purpose. When discussing screws, the
pitch, or the longitudinal distance between threads, and the thread depth are the two main ways to classify screw types. Cortical screws
have a thread pitch and depth designed for hard, dense cortical bone. Cancellous screws have longer thread pitch and depth designed
for softer cancellous bone. Self-tapping screws have a cutting flute at the tip of the screw. This allows the screw to cut the thread
pattern into the bone without using a tap. Locking screws have threads on the head of the plate, anchoring the screw within the plate.
The surgical assistant must know the difference between screws when assisting in a surgical fixation. When the surgeon measures the
drilled hole, the surgical assistant will obtain the appropriate screw for the surgeon as the surgeon maintains reduction of the bone.
Plating in surgery
Once the bone has been reduced and a plate is selected the bone is ready for fixation. The first step of fixation is drilling, performed
with either a battery or nitrogen powered drill. Different orthopedic screws require different size drill bits depending on the inner
diameter of the screw. A 3.5mm cortical screw will require a 2.5mm drill bit while some locking cortical screws require a requires a
2.8 drill bit. It is important for the surgical assistant to know these relationships so that the appropriate drill bit is given. When the hole
is drilled the surgeon will measure the depth using a depth gauge and tell the surgical assistant what screw length is needed. It is
important for the surgical assistant to measure and ensure the designated screw is the correct length before handing to the surgeon.
Once the hole is measured, it may or may not be tapped, depending on whether or not the screw is self-tapping or not. The tap used is
the same size as the screw. For example, a 3.5mm screw will use a 3.5mm tap. The tap can either be hand tapped with a handle
attachment or powered with a drill. The screw can also be placed by hand or with a drill.
Arthroscopy
The surgical assistant must understand the instrumentation of arthroscopy in order to properly set up the arthroscope for the procedure.
First, a camera is used to capture images and film video of the joint during the procedure. This camera connects to the arthroscope, a
telescoped lens that mounts to the camera. A light source the attaches directly to the arthroscope. It is a fiber optic cable that emits a
light through the scope in order for an image to be seen within a closed joint capsule. The arthroscope is inserted into the joint through
a cannula. The cannula protects the arthroscope and maintains the portal that allows access to the joint. This cannula requires a blunt
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trocar in order to be place within the joint capsule, and attaches to fluids to the cannula and provides a constant flow to ensure
visibility throughout the procedure.
Other instruments in arthroscopy include hand instruments and arthroscopic shavers. The hand instruments used in arthroscopy are
arthroscopic graspers, meniscal punches, probes, and curettes. Arthroscopic shavers attach to a power source and debride tissues
within the joint with a burr attachment that rotates to cut away at soft tissues, cartilage, and bone.
Complications
Complications do occasionally occur in orthopedics. Complications can be excessive bleeding, where hemostasis is needed, or
equipment failure, such as a broken screw or drill bit within the bone. In the event of a surgical complication, the assistant must
provide proper use of suction and retraction to allow visualization. In moments where hemostasis is needed, the technician should
ensure that cautery and hemostats are readily available for the surgeon.
Bandaging and splinting
Robert Jones
The Robert Jones bandage uses large amounts of cast padding to help immobilize limbs distal to the elbow or stifle joint. The use of
an extremely thick secondary layer of cast padding helps prevent any vascular compromise when applying the tertiary layer of
compression. This bandage however is considered a very cumbersome bandage and sometimes difficult for small animal patients to
maneuver with and therefore avoided when possible.
Modified Robert Jones and splints
The Modified Robert Jones bandage can also be referred to as a soft padded bandage. It involves a smaller secondary layer of cast
padding compared to the Robert jones bandage. This bandage also allows easy incorporation of splint material. Splints can be made
out of fiberglass, thermoplast, aluminum rods, or premade splints such as spoon splints.
Stirrups made from strips of porous tape are applied to the distal portion of the limb, on medial and lateral aspects. Cast padding is
applied from the distal aspect to proximal aspect of the limb and then back down the limb, proximal aspect to distal aspect. The cast
padding should overlap about 50% with each pass around the limb. Toes are typically exposed in order to report signs of swelling.
Two to three layers of cast padding are generally applied followed by a layer of elastic gauze. The elastic layer is applied similar to the
secondary layer, from distal to proximal, overlapping 50 % with each pass, adding compression evenly. If the bandage is incorporating
a splint, the splint is added at this time and another layer of elastic gauze is wrapped around the splint and bandage. Finally, an outer
covering of Vetwrap or elastikon is then applied, avoiding tightness, from distal to proximal, overlapping about 50% with each pass.
Additional elastikon can be added to the distal end of the bandage to avoid wear as the patient walks on the limb.
References
Bassert J, Thomas J. McCurnin’s Clinical Textbook for Veterinary Technicians. Elsevier, 2014, pp 1129-1154.
Booth, HW. Instrumentation, in Tobias KM, Johnston SA: in Veterinary Surgery Small Animal. Elsevier, 2011, pp 152-162.
Canapp, SO, Campana DM, Fair LM. Orthopedic coaptation devices and small-animal prosthetics, in Tobias KM, Johnston SA: Veterinary Surgery
Small Animal. Elsevier, 2011, pp 628-646.
MacPhail, C. Surgical Instrumentation, in Fossum, TW: Small Animal Surgery. Elsevier, 2013, pp 53-62.
Fossum, TW. Preparation of the Operative Site, in Fossum, TW: Small Animal Surgery. Elsevier, 2013, pp 39-44
Lavin, LM. Radiography in Veterinary Technology. Elsevier, 2007, pp 153-163, 181-182.
Johnston SA, vo Pfeil DJF, Dejardin LM, Weh M, Roe S, Internal Fracture Fixation, in Tobias KM, Johnston SA: in Veterinary Surgery Small Animal.
Elsvier, 2011, pp 590-600.
Schulz, KS. Arthroscopy, in Tobias KM, Johnston SA: in Veterinary Surgery Small Animal. Elsevier, 2011, pp 1135-1158.
Swaim SF, Reberd WC, Shike KM: Small Animal Bandaging, Casting and Splinting Techniques.
Wiley-Blackwell, 2011, pp 47-108.
Tear, M. Small Animal Surgical Nursing: Skills and Concepts. Elsevier, 2012, pp 177-194.
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Do I Need a Flu Shot?
Jennifer Chatfield, DVM, DACZM
4J Conservation Center
Dade City, FL
With ~75% of all emerging pathogens zoonotic, a One Health approach to infectious disease evaluation becomes increasingly more
prudent. No disease better demonstrates the validity of One Health than zoonotic influenzas. With seemingly infinite combinations of
the key components, hemagglutinin (H) and neuraminidase (N), long-term physiological immunity to influenza seems nearly
impossible. It is critical for veterinarians to understand the key features of this virus and how to best respond to emerging influenzas.
RACE required objectives
1. Describe the influenza virus molecule and discuss the concepts of antigenic drift, shift and mutation
2. Review the history of pandemic influenzas in different species and their impact on society
3. Discuss the prominent influenzas and their clinical implications
Key points
Influenza transmission is through aerosolized droplets and other respiratory secretions. Influenza survives in the environment, even
under some less favorable conditions. Animals and humans are able to shed influenza prior to the onset of clinical symptoms for up to
72 hours, making biosecurity difficult to perform effectively.
Diagnostic and therapeutic points
Diagnosis can be based on clinical presentation or in conjunction with a variety of diagnostic tests. Supportive care shouldn’t be
overlooked in non-food animals. Early supportive care and isolation from cohorts should be definitive. Additionally, personnel
should be careful and maintain good hygiene practices to prevent cross-species transmission. Antivirals are sometimes effective in
animals, but must be given very early in infection to be effective. Some resistant influenzas do exist. Vaccinate!
Early response to supportive care with less severe fever, decreased respiratory secretions, etc., are generally good prognostic
indicators. Treatment in commercial production operations is not possible and all influenza infections in animals should be treated as
significant.
Given the likelihood that the next influenza pandemic will be the result of a recently adapted animal strain infecting humans,
veterinary medical professionals should be vigilant in their own disease prevention and get routine annual influenza immunizations.
“Take home” points
1. Influenza is unpredictable and cross-species transmission does occur.
2. Virus shedding is possible for 48-72 hours prior to the onset of clinical symptoms, so good biosecurity should be
practiced when bringing new animals into an existing group.
3. Influenza is not new – it has just evolved.
4. Antivirals are most effective when initiated early in disease onset.
5. Veterinarians and their staff should be vaccinated annually to prevent influenza transmission.
References/suggested reading
http://www.flu.gov/pandemic/history/
Komadina N, McVernon J, Hall R, Leder K. A historical perspective of influenza A(H1N2) virus. Emerg Infect Dis. 2014 Jan
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Surgical Assist Pearls for Technicians
Sara Colopy, DVM, DACVS
University of Wisconsin
Madison, WI
William Stewart Halsted (1852-1922) was one of the most innovative and influential surgeons in American history. He was one of the
founders of Johns Hopkins Hospital, he introduced several new operations (including the radical mastectomy), and is credited for
starting the first formal surgical residency training program in the United States. In addition, he is well known for creating “Halstead’s
Principles,” a list of surgical guidelines that transformed patient outcome following surgery. These principles (control of bleeding,
accurate anatomical dissection, complete sterility, exact approximation of tissue in wound closures without tension, and gentle
handling of tissue) are to this day considered the cornerstone of modern surgery, and would later become proven through controlled
clinical trials. Over and over, it has been statistically proven in both human and veterinary medicine that two of the most important
risk factors for development of surgical site infection (SSI) are time of surgery and overall time of anesthesia. This was documented in
a large retrospective study of dogs and cats (Nicholson et al, 2002) showing that total surgery time and total anesthesia time were
significantly longer in animals that developed postoperative SSI. A more recent study in dogs undergoing surgery for cruciate rupture
showed that for ever minute increase in surgical time and anesthesia time, the likelihood of developing SSI increased by 7% and 4%
respectively (Yap et al., 2015). Use of postoperative antibiotics did not lower this risk. Another study showed that increased anesthesia
time increased the risk of SSI independent of the surgery time, meaning that any diagnostic testing or preparation for surgery should
be efficient and kept to a minimum in order to decrease the incidence of SSI (Beal et al., 2000).
These studies have important implications for the entire surgical team. The technicians must have complete knowledge of aseptic
technique, surgical instrumentation, sterilization processes, operating rooms, and patient and personnel surgical preparations.
Everything that happens before, during, and after surgery should be planned in advance so that time is not wasted while the animal is
under anesthesia. Gowns, caps, gloves, masks, and booties are laid out ahead of time, the operating room is clean, and all monitoring
devices are assured to be in working order. Technical knowledge of the surgical instrumentation and fundamental techniques improves
the ability of the technician to aid the primary surgeon’s progress efficiently. For example, understanding the planned surgical
procedure and communicating with the surgeon allows the technician to anticipate instruments and suture material that might be
needed during the procedure. These instruments are gathered in the operating room before the animal is under general anesthesia so
that time is not lost retrieving an instrument during surgery. If all of this is done effectively ahead of time, the focus is entirely on
efficiently prepping the patient for surgery once anesthetized. In addition, the technicians are available to monitor the patient and
assist in surgery, further contributing to the safety and efficiency of the procedure.
Preoperative preparation
There are several ways veterinary technicians and assistants may be involved before the animal enters the operating room. The lead
technician will often work closely with the doctor to organize the surgery schedule for the day. If admitting the animal into the
hospital, the technician obtains a thorough history from the client. It is important to determine any pre-existing illnesses that may alter
the anesthetic plan, whether the animal has eaten that day, what medications have been given, and if the animal is feeling well. The
technician may also help with the physical examination by collecting vital signs and recording this information in the medical record.
He or she may also review the basics of the surgical procedure with the client.
Once the animal is admitted, the veterinarian will choose the appropriate preanesthetic and induction drugs to be administered. If
within 20-30 minutes of surgery, the preanesthetic drugs may be given. The technician will often prepare the drugs as well as all of the
necessary equipment needed for induction and anesthesia maintenance. Appropriate sized endotracheal tubes are chosen, and materials
needed for IV catheter placement are made readily available. The anesthesia machines are checked and the vaporizer should contain
sufficient amounts of liquid anesthetic. Oxygen pressures should be checked as well, and the reservoir bag changed if necessary. All
of the monitoring equipment (thermometer, pulse oximeter, electrocardiogram machine, capnography, blood pressure machine, etc.) is
gathered and checked for proper function. Once everything is ready to go, the animal can be induced under anesthesia.
An intravenous catheter may be placed depending on the patient’s age, physiologic condition, and procedure to be performed. The
induction agents are given to effect, and the animal is intubated. Depending on hospital policy, remaining induction drugs are either
discarded or kept on hand to be used later if the animal suddenly starts to awaken during the procedure. At this point, the endotracheal
tube is secured and connected to the anesthesia machine. The oxygen flow and gas vaporizer is set. The cuff should be inflated
incrementally, stopping once you can no longer hear air movement – this is achieved by placing your ear near the patient’s mount and
squeezing the reservoir bag with the pop off valve closed (“giving a breath”). The pop off valve is then immediately reopened. This
method of cuff inflation helps avoid damage to the trachea, an unfortunately relatively more common catastrophic complication of
anesthesia. At this point, the monitoring devices are connected to the patient. Initial vital signs are recorded in the anesthesia log. The
technician then shaves the fur in the surgical field and aseptically prepares the skin.
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Antibiotics are not necessary for short, clean procedures. Invasive surgeries, surgeries with potential contamination, and lengthy
surgeries (>2 hours of anesthesia) are examples of surgeries where perioperative antibiotics are recommended due to the increased risk
for SSI. Antibiotics are also recommended for any procedure in which prosthetic materials are implanted in the patient (orthopedic
implants or permanent suture materials) as infection would be catastrophic for the outcome of these procedures. If perioperative
antibiotics are to be given, they are given SQ or slowly IV after anesthetic induction and then repeated every 90-120 minutes until the
end of surgery. Oral antibiotics are insufficient for reaching peak antimicrobial levels within the tissue at the time which
contamination may occur during surgery. Common antibiotic choices include cefazolin or cefoxitin as they are effective against
bacteria commonly found on the skin.
It is ideal to always have 2 people helping with anesthesia induction so that one person can place the IV catheter, induce
anesthesia, and monitor the patient while the other helps restrain the animal and aseptically prepares the skin for surgery. This allows
optimal efficiency as well as safe monitoring of the patient while under anesthesia.
Aseptic patient preparation
Aseptic technique refers to the practice of preventing the growth of microorganisms (bacteria, viruses, and fungi) on skin and
instruments in order to prevent infection. Disinfection means the destruction of microorganisms with the exceptions of spores.
Disinfectants are chemical agents (chlorhexidine, bleach, etc.). Proper contact time is required for efficacy, and proper dilution is
required for both safety and efficacy. Sterilization is a term that means the destruction of all microorganisms, including spores. This is
typically done by us of an autoclave (via heat, moisture, and pressure) or gas sterilization. Both disinfection and sterilization are terms
that apply only to inanimate objects (e.g. instruments, surgery tables, and counters).
Antiseptics are chemical agents that decrease the number of microbes on skin. They are used to prepare the surgeons hands and the
patient’s skin before surgery. Common antiseptics include chlorhexidine, povidone-iodine, and alcohol. As with disinfectants, proper
contact time between the antiseptic and skin surface is required for efficacy. When aseptically preparing skin, cleaning is performed
starting in the area that is most important to clean (the planned incision site) and working toward the area where asepsis is less critical
(the edges of the hair clip margin). If scrubbing into surgery, the doctor’s or technician’s hands are washed in a similar stepwise
fashion from fingertips to elbows.
Surgical assisting
Once in the operating room, there are several ways the technical team can assist to minimize the length of the procedure and overall
time the patient is under anesthesia. Generally, there is a technician dedicated to monitoring the anesthesia and ascertaining the proper
anesthetic depth, periodically checking for palpebral reflexes, mucous membranes, pupillary positioning, capillary refill time, heart
and respiratory rates. A surgical log should be maintained and values recorded every five to ten minutes, alerting the veterinarian to
any abnormal values.
The technician helps position the patient on the surgery table. Positioning is important as it can facilitate a surgical procedure (or
conversely, interfere with the procedure by obstructing exposure to the region of interest). The animal is secured to the table carefully,
avoiding excess tension that may injure the limbs. Thermal support is ideally provided in the form of warm air or warm water
blankets. Extreme care must be taken to avoid patient contact with electric heating pads and hot rice socks as severe thermal burns
have resulted from the use of these products. In our hospital, we only provide thermal support in the form of warm air and water
blankets.
The technician may also be asked to retrieve additional instruments if necessary; however, as discussed previously, it is ideal to
anticipate any instruments and suture material that may be necessary and keep them in the operating room within reach of the
technician. This, again, promotes a shorter procedure and anesthesia time and contributes to the overall safety of the patient.
The technician is often asked to help assist with the actual surgical procedure. Having a sterile technician or assistant scrubbed into
the procedure can significantly improve the quality and efficiency of the surgery. Depending on the surgery, the technician may be
asked to retract or hold the tissue, assist with hemostasis, lavage and moisten the surgical area with sterile saline, provide suction if
necessary, and grab a sterile instrument from the surgical pack. Anticipation of the surgeon’s needs and temporal steps in surgery can
dramatically decrease the total operative time, ultimately improving patient outcome and enabling the surgical team to accomplish
more procedures in a given day. Again, it is optimal that the sterile assistant is not the same person that is monitoring anesthesia so
that abnormal vital signs are not missed while the technician is focused on the procedure. The assistant may also be asked to count
gauze sponges at the start of surgery and before the incision is closed to confirm that no sponges have been left in the abdomen.
At the end of surgery, the technician monitoring the patient should start to decrease the anesthetic depth while the surgeon is
closing the incision site. The anesthetic gas is discontinued once the incision is completely closed. The animal may be maintained on
oxygen for a short period of time while the skin around the incision is cleaned. Typically, left over saline from surgery or plain tap
water is sufficient for cleaning the skin and fur if necessary. Hydrogen peroxide is not necessary to remove blood, as water is quite
effective and hydrogen peroxide can be damaging to the healing incision. The endotracheal tube is left in place as long as possible
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during recovery to maintain an open airway; however, the technician remains at the animal’s side, ready with an empty syringe to
deflate the cuff. The endotracheal tube is removed once the animal is swallowing regularly (and the gag reflex has returned) to avoid
the animal biting and severing the tube during recovery. Temperature, heart rate, respiratory rate and effort are monitored until the
patient is fully awake. Pain medication is given if necessary upon recovery.
Once the animal is fully awake and stable, the technician can proceed to clean the surgical suite and prepare it for the next patient.
The table is cleaned, and instruments are removed and brought to an area to be soaked and scrubbed. Instruments are cleaned using a
cleanser specifically made for that purpose. The instruments may be placed in an ultrasonic cleaner and rinsed and placed in a
lubricant bath. They are then set and wrapped for sterilization.
Technicians and surgical assistants should become familiar with common instruments and their uses (below). It is also helpful to
have the instruments labeled or color coded that belong in specific packs to improve efficiency in pack preparation. Instruments that
are infrequently used, or of which there are limited numbers of them, are wrapped separately in self-sealing surgical instrument
sterilization pouches labeled with the instrument name and date of sterilization. Knowing the instrument name and use not only helps
in pack preparation, but also allows the technician to grab the instrument quickly if needed in surgery. You may choose to create a list
with pictures to be kept in the operating area for quick reference and for training new staff.
After surgery, the technician will continue to monitor the patient regularly and administer treatments and pain medications as
necessary. He or she may also prepare the charges and discharge summary for the client (to be reviewed by the veterinarian) and
dismiss the patient from the hospital.
Academy of Veterinary Surgical Technicians (AVST)
In 2010, the National Association of Veterinary Technicians in America (NAVTA) officially recognized the Academy of Veterinary
Surgical Technicians (AVST). The group was formed with the intention of creating recognition and advanced educational and training
opportunities for technicians who spend the majority of their time dedicated to surgery. Veterinary Surgery is defined by advanced
knowledge of surgical procedures and instrumentation (including instrument identification and care), proper sterilization techniques,
principles of infection control, aseptic techniques, perioperative patient care, physical rehabilitation and a thorough knowledge of the
anatomy and pathophysiology of animals. The purpose of the AVST is more clearly outlined in their mission statement:
“The purpose of the Academy of Veterinary Surgical Technicians (AVST) is to increase the competence of those who perform
specialty duties in the field of veterinary surgery. The academy will strive to ensure that the veterinary surgical technician possesses
superior knowledge and skill in the care and management of surgical cases, surgical instruments, and the surgical suite. AVST will
offer candidates advanced continuing education opportunities and will establish educational and professional experience prerequisites
to earn recognition as a VTS (Surgery).
The requirements for membership/certification include the following:
1. Experience prior to starting the application: 10,000 hours (5 years) work experience, 3 years focused in veterinary
surgery. 75% of time dedicated to veterinary surgical duties
2. Continuing education: 40 hours within 5 years prior to application
3. Documentation: Surgical skills, case logs, case reports, letters of recommendations
4. Member of the National Association of Veterinary Technicians in America or another provincial association
(recommended)
5. VTS (Surgery) credentialing examination – at the American College of Veterinary Surgeons summit in October.
6. Approval by the Executive board.
Once membership has been approved by Board, the technician is permitted to use the Veterinary Technician Specialist designation
“VTS (Surgery).” More information is available at the following website: http://www.avst-vts.org/
Summary
The technicians and assistants are a vital part of the surgical team from the time the animal enters the hospital until discharge. Being
knowledgeable about the patient’s condition, surgical procedure, drugs and equipment, and being proactive in regards to preparation
for surgery allows for a more efficient surgical procedure. Increased efficiency allows the doctors and technicians to see more patients
and do more procedures, ultimately increasing hospital revenue. In addition, the resultant decreased anesthesia and surgery time leads
to a better outcome with less potential for complications to the patient.
Instruments
Scalpel handle and scalpel blade
Scalpels are used for making incisions in the skin, as they are atraumatic and cause minimal cell death. The most common blades used
in small animal practice are the #10 and #15 blade. The #10 blade is frequently used for skin incision. The #15 blade may be used for
smaller patients and for finer dissection or curvilinear incisions. The sharp-point #11 blade is used for stab incisions or pinpoint
dissection. The #12 blade is curved and sharply pointed and frequently used for declaw procedures.
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The disposable scalpel blade offers a fresh, sterile, sharp blade for each use. The scalpel blade may be held with the fingers or
forceps, but should be loaded and unloaded using a pair of needle-driving forceps. The blade should be pointed downward, away from
people or the patient when unloading it, and care should be taken to avoid breaking the blade. The blade or fragments of the blade can
become projectiles and injure eyes and other tissue.
Scissors
These are used for blunt and sharp dissection of tissues. There are varieties for cutting delicate tissues, fascia and cartilage, and for
sutures and bandages. “Sharp Blunts” or “suture scissors” are used strictly for cutting tough suture material that can be damaging to
the fine blades of other scissor types. Metzenbaum scissors are thin and delicate and may be curved or straight. They are typically used
for cutting delicate tissue. Mayo scissors are much heavier than Metzenbaum scissor and also may be curved or straight. The Mayo
scissors are designed for cutting tougher tissue such as ligament, tendon, and skin.
Thumb forceps
These are spring action instruments made for grasping and holding tissue during manipulations and should be held like a pencil. The
two most common types include Brown-Adson (which have sharp teeth for grabbing tough tissue such as tendon or muscle fascia) and
DeBakey (which have finer teeth for grabbing more delicate tissues). Other thumb forceps include rat-tooth and Russian forceps,
which are used less commonly.
Grasping forceps
These are tissue-holding instruments that have finger rings and a locking mechanism. They are designed to firmly hold tissue for
manipulation and for crushing.
a. Crushing forceps – these forceps are used to achieve hemostasis and crush tissues. A wide range of sizes is available.
Examples of hemostatic forceps would include: mosquito (Halsted), Kelly, and Crile. Examples of crushing forceps include:
Carmalt, Rochester-Pean, Oschner
b. Tissue forceps – these forceps are used to grasp or occlude vascular structures or hollow organs without damaging them.
Grasping forceps would include: Babcock, Allis (although Allis tissue forceps may crush tissues locally). Occlusive forceps
include: a variety of vascular forceps named after surgeons (e.g. Satinsky or Cooley forceps for occluding vessels and Doyen
forceps for occluding the bowel).
c. Towel Clamps – these are used to fasten drapes to one another or to the patient. The type used most frequently in veterinary
surgery has piercing tips (Backhaus, Roeder, Lorna-Edna).
Retractors
These are used to facilitate exposure of the field of operation so that dissection can proceed unhindered. They are classified into two
groups: hand-held (Army-Navy, Miller-Senn, Parker, malleable, etc.); and self-retaining (Balfour, Finochietto, Weitlaner, Beckman,
Gelpi). Each retractor is designed for a specific use.
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Balfour--Self-retaining retractors most commonly used for abdominal surgery.
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Finochietto--Self-retaining retractors used to spread the ribs or sternum for thoracic surgery.
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Green, Army-Navy, Parker, Senn, spay hook are common hand held retractors that are used for retracting narrow planes
of tissue.
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Gelpi and Weitlaner--Self-retaining retractors generally used to retract muscle fascia during orthopedic, neurologic or
soft tissue surgeries, and are often used in pairs.
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Ring Retractor (from Lone Star Industries)--This inexpensive retractor is circular or rectangular and made of plastic. It
utilizes six to eight skin hooks with elastic bands to retract tissue atraumatically. This very convenient and functional
retractor may be used for many types of soft tissue surgery, and is especially helpful for total ear ablation surgery,
neurologic surgery, or perineal surgery. It is also useful for small patients and exotics.
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Stay sutures may also be used for retraction, in which a suture is passed through the tissue and held with a hemostatic.
This is a great technique for tissues that are sensitive to injury but need to be retracted for an extensive period of time
(e.g. stomach or bladder).
Needle holders/ needle driver
These are grasping forceps specially designed to hold a curved needle during suturing. A large variety is available to meet the needs of
all types of surgery. They either come without (Mayo-Hegar) or with (Olsen-Hegar) suture cutting scissors along with the needle
holder. Though potentially more convenient for the surgeon, the combination of the needle holder and scissors within the same
instrument compromises the quality of each instrument. In addition, inadvertent cutting of suture may occur by surgeons not
accustomed to using the combined instrument. The Castroviejo needle holder is smaller, spring loaded, and designed for use in micro
surgery (ocular or vascular surgery)
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Electrocautery
Electrocautery units can be used for incising tissue as well as hemostasis (control of bleeding). Most units can be using in a cutting
mode or a coagulation mode. The cutting mode causes less tissue necrosis and hemostasis, whereas the coagulation mode does not not
cut as well but provides more hemostasis. Cautery causes some degree of tissue necrosis, leading to increased inflammatory and
potentially a delay in wound healing if excessive. Electrocautery is either unipolar (where a ground plate receives the current dispersed
through the animal’s body) or bipolar (where the current goes directly between the tips, cauterizing on the tissue between the tips.
Bipolar cautery is less powerful, but good for finer, more delicate hemostasis, or hemostasis near vital structures.
Suture materials
There are many types of suture materials available for use in veterinary medicine. A general knowledge of suture material is helpful
when assisting in surgery. In general, suture materials are categorized several criteria:
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Absorbable (strength lost in less than 60 days) vs. nonabsorbable (maintain strength greater than 60 days)
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Organic (natural) vs. synthetic
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Monofilament (single strand) vs. multifilament (several strands spun, twisted, or braided together)
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Handling characteristics
•
Tissue reactivity
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Strength
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Time until strength is lost
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Time until absorbed
The specific suture material is chosen based on these criteria in conjunction with the estimated healing time of a particular tissue as
well as the degree of tension the tissue is subject to. For example, the oral mucosa heals quickly vs. the linea alba (the tendonous
midline of the abdomen) heals very slowly. Therefore, the same type of suture material would not be ideal for both locations.
In general, most general practices will stock one of each of a short-acting absorbable suture, a long acting absorbable suture, and a
non-absorbable suture. Most referral surgical facilities may stock a few more for use in diverse procedures. The following summarizes
some of the more common suture materials and appropriate uses for each:
Short-acting absorbable
Other than chromic catgut, most of these sutures retain strength for 2-3 weeks and are ideal for tissues such as the subcutaneous fat,
mucosal organs (GI tract, urinary tract, oral mucosa, etc.), and vessel ligation. The monofilament sutures (Monocryl, Monomend, and
Biosyn) are commonly used for intradermal skin closure.
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Chromic catgut – Very short acting natural multifilament suture. Limited used due to relatively low strength and high
tissue reactivity. Used most commonly for ligating multiple small vessels
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Polyglactin 910 (Vicryl) – Multifilament synthetic suture
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Polyglecaprone 25 (Monocryl) – Monofilament synthetic suture
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Glyconate (Monomend) – Monofilament synthetic suture
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Glycomer 631 (Biosyn) – Monofilament synthetic suture
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Polyglycolic acid (Dexon) – Multifilament synthetic suture. Not ideal for urinary tract surgery.
Long-acting absorbable
These are both monofilament absorbable sutures that retain strength longer than the other absorbable suture materials (Strength lasts
for 2 months, absorbed in 180 days). Great for muscle fascia, tendon, and the abdominal wall.
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Polydioxanone (PDS)
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Polyglyconate (Maxon)
Non-absorbable
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Polyamide/Nylon (Ethilon, Dermalon, Surgilon, Monosof) – used mostly for skin closure.
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Polypropylene (Prolene, Surgilene, Surgipro, Fluorofil) – used for skin closure and ligament/tendon reconstruction. Also
used for the abdominal wall when delayed healing is expected (Cushing’s disease, cancer, renal failure, etc.)
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Steel – Strongest and longest acting with the least reactivity. Used for ligating small vessel (hemoclips) and in numerous
stapling devices (skin staples,
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Silk – Natural multifilament suture. More reactive and loses strength faster than other nonabsorbable suture. Great for
ligating large vessels (e.g. vessels supplying the limb for an amputation or ligation of a patent ductus arteriosus (PDA))
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Polymerized Caprolactam (Vetafil, Supramid, Braunamid) – used mostly for skin closure. Not sterile, so should not be
placed in a body cavity due to formation of abscesses and fistulas
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Polybutester (Novafil)
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Polyester (Mersilene, Dacron, Ethibond)
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References
Beal MW, Brown DC, Shofer FS. The effects of perioperative hypothermia and the duration of anesthesia on postoperative wound infection rate in
clean wounds: a retrospective study. Vet Surg 2000;29(2):123-7.
Nicholson M, Beal M, Schofer F, Brown DC. Epidemiologic evaluation of postoperative wound infection in clean-contaminated wounds: A
retrospective study of 239 dogs and cats. Vet Surg 2002;31(6):577-81.
Yap FW, Calvo I, Smith KD, Parkin T. Perioperative risk factors for surgical site infection in tibial tuberosity advancement: 224 stifles. Vet Comp
Orthop Traumatol 2015;28(3):199-206.
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Insights into Anesthetic Drugs
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
Anesthesia carries with it a certain degree of risk and there is no single best way to anesthetize animals. Appropriate drug selection is
important and largely dependent on the patient’s physical status, temperament, type of procedure, present and anticipated pain,
familiarity of drugs available and cost.
One size does not fit all
It is generally not recommended to use pre-mixed drug cocktails like BAG or kitty magic. These cocktails do not allow for tailoring of
the protocol to the specific temperament of the patient and often result in inappropriate dosing. There is also room for human error in
mixing up large volumes of drugs, recording controlled substances and breaks in aseptic technique when pulling from a multi-dose
vial. Best practice includes accurately drawing up each drug individually and then mixing them together for delivery. Designing an
anesthetic protocol is easy if you remember PIMP, preanesthetics, induction, maintenance and pain management.
Pre-anesthetics and balanced anesthesia
Pre-anesthetics are an essential component to successful anesthesia. Pre-anesthetics help to calm and sedate anxious, frightened or
fractious patients. It streamlines restraint and decreases patient and staff stress. Reduces the necessary dose of induction drug, helps to
decrease the amount of inhalant needed for maintenance of anesthesia, promotes smoother inductions and calmer recoveries along
with an easier to manage maintenance stage of anesthesia. Pre-emptive pain management, or giving an analgesic in anticipation of
pain, should be part of the preanesthetic period. Balanced techniques along with pre-emptive analgesia can make post-operative pain
easier to manage. Balanced anesthesia is the concurrent administration of smaller quantities of multiple drugs allowing them to work
synergistically- combined drug effectiveness is greater than the sum of each part- which allows for the use of less of each drug
minimizing side effects and maximizing therapeutic benefit.
Pharmacokinetics and pharmacodynamics
Understanding anesthetic drugs requires an appreciation of each drug’s pharmacokinetics and pharmacodynamics. Pharmacokinetics
refers to the effect the body has on the drug and pharmacodynamics refers to the effect the drug has on the body. Drugs enter the
body via the bloodstream and bind to specific receptors located in target organs and tissues to exert specific effects- for anesthetics
these effects are usually central nervous system depression or stimulation. Agonists are drugs that bind to and stimulate a specific
receptor found in target tissues. Antagonists bind to but do not stimulate receptors- most antagonists competitively bind to receptors
and displace agonists effectively ‘reversing’ the action of the initial drug. A partial agonist is a drug that only partially stimulates a
receptor and an agonist-antagonist binds to more than one receptor, agonizing one and antagonizing another.
Benzodiazepines like diazepam and midazolam are sedatives that work by increasing the activity of an inhibitory
neurotransmitter- gamm-aminobutyric acid or GABA. This class of drugs is used for anti-anxiety and calming in ill or geriatric
animals, skeletal muscle relaxation, appetite stimulation and as an anticonvulsant. Benzodiazepines do not provide any analgesia and
cause very minimal (if any) cardiovascular and respiratory depression. They have the tendency to decrease inhibition in young,
healthy animals causing paradoxical excitement especially when given alone. Benzodiazepines are reversible with the drug
flumazenil. Onset time is rapid and duration of action is 1-3 hours. Diazepam: propylene glycol based, for IV use only Midazolam:
water based, can be given IM, SQ or IV
Phenothiazines like acepromazine or ‘ace’, is a tranquilizer often used as a preanesthetic in cats, dogs and horses. Acepromazine is
an alpha-1 adrenergic and dopaminergic receptor antagonist that causes dose dependent sedation and a generalized disinterest in
surroundings. It has no analgesic properties and it can mask the signs of pain without alleviating them. Ace can cause peripheral
vasodilation that can negatively affect blood pressure and body temperature. It also has antiemetic and antihistamine effects. Onset
time is around 15 minutes with peak effect at 30 minutes. Duration of action is variable and dose-dependent and can last 4-8 hours in
small animals.
Alpha-2 adrenergic agonists provide sedation, muscle relaxation and analgesia. This class includes the drugs detomidine,
dexmedetomidine and xylazine which are commonly used in both large and small animals. Dexmedetomidine is more specific for the
alpha-2 receptor making the side effects associated with this drug class less prominent compared to xylazine and therefore safer for
our small animal patients. Sedation and analgesia is dose dependent as is the duration of action. Peripheral vasoconstriction leads to
pale mucous membranes and a reflex bradycardia. Vomiting and increase urine production are not uncommon. Some animals may be
refractory to the drug. Co-administer with an opioid and allow patients to sedate in a quite place to decrease stimulation. Alpha-2
agonists are fully reversible with atipamezole (dexmedetomidine) or yohimbine (xylazine). The volume of reversal given should be
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the same as the volume of drug given previously. Dexmedetomidine: onset time is 5-15 minutes IV, 15-30 minutes IM. Duration of
action is around 90 minutes.
Opioids provide analgesia by binding to specific receptors located in the brainstem and spinal cord. Some opioid receptors can
also be found in peripheral tissues. Opioids don’t remove pain; they raise the threshold making pain more tolerable. There are two
main types of opioid receptors, kappa and mu. Pain is mediated by mu receptors in mammals and kappa in birds. There is some
evidence to suggest that kappa receptors exist in higher numbers in the gut compared to the peripheral tissues in mammals allowing
kappa agonists to provide good visceral analgesia. Pure mu agonist opioids include morphine, hydromorphone, oxymorphone,
fentanyl and methadone. This group of drugs fully bind to the mu receptor and are effective at providing analgesia. They can also
cause sedation, especially in geriatric, pediatric or debilitated animals. Pure mu agonist opioids cause minimal cardiovascular
depression and dose dependent respiratory depression by increasing the resting partial pressure of carbon dioxide or PaCO2.
Bradycardia from vagal stimulation, vomiting from direct stimulation of the chemoreceptor trigger zone (CTZ), urine retention from
decrease sensation and urge, antitussive properties and resetting of thermoregulation are not uncommon side effects of this drug class.
Morphine
Histamine release when given IV, poor oral bioavailability, vomiting is common, high lipid solubility make it a great for epidural use
(preservative free formulation is recommended). Duration of action is 4-6 hours.
Hydromorphone/oxymorphone
Less vomiting compared to morphine, no histamine release IV, hydromophone may cause hyperthermia in cats. Duration of action is
2-3 hours.
IV fentanyl
Very potent synthetic opioid, 3-8 minute onset time IV with a short duration of 20-30 minutes. Given as a constant rate infusion
(CRI).
Fentanyl patch
Variable absorption that may not provide adequate analgesia if used as a sole means of analgesia. Takes 12-18 hours to reach
therapeutic plasma levels and can potentially last for 3 days. Dose accordingly!
Methadone
Pure mu agonist and NMDA antagonist (helps prevent wind-up pain by blocking n-methyl d-aspartate). Good analgesia and less
sedation compared to morphine. Duration of action is 3-4 hours.
Agonsit/antagonist drugs stimulate one receptor while blocking another. Drugs like butorphanol and nalbuphine stimulate the
kappa receptor while blocking the mu receptor making them only effective at treating mild pain in mammals. Because they block the
mu receptor they can be used to reverse any unwanted effects of a pure mu agonist opioid while maintaining some analgesia.
Butorphanol
Mild analgesic with a ceiling effect (more drug does not equal more analgesia), short duration of action lasting 45 minutes- sedation
may last longer, controlled as schedule IV
Nalbuphine
Mild analgesic, short duration of action lasting only 30 minutes, not a controlled substance
A partial agonist opioid is a drug that does not fully bind to the mu receptor making it less effective than a pure mu agonist like
morphine. Partial agonists are drugs that only partially bind to the mu receptor exerting an effect that is not as great
Buprenorphine
Very high affinity for the mu receptor making the use of subsequent opioids ineffective until buprenorphine has worn off. Slow onset
of action taking it nearly 45 minutes to provide pain control but long duration of action 6-8 hours, great transmucosal absorption in the
cat but only about 30% bioavailable transmucosally in the dog, class III controlled substance
Sustained release buprenorphine
(SR) is not an FDA approved product but is available through a compounding pharmacy. It is given SQ and has been shown to
provide up to 72 hours of analgesia. Reversal is difficult and may require hospitalization.
Simbadol
High potency buprenorphine (1.8 mg/ml) dosed at 0.24 mg/kg and FDA approved for use in cats. Provides 24 hours of analgesia and
can be q24 for up to 3 days. SubQ ONLY.
Opioid antagonists completely reverse the effects (analgesia, sedation and cardiopulmonary depression) of all circulating opioids
including endogenous ones. These drugs should only be used in the face of an absolute opioid overdose because their use removes
ALL analgesia along with any other effects. An acute awareness of pain can lead to catecholamine release from sympathetic
stimulation which may result in cardiac arrhythmias, hypertension and possibly death. Redosing may be necessary due to the short
duration of action of naloxone compared to most opioids.
•
Naloxone: onset 1-2 minutes IV, 5 minutes IM, duration of action 30-60 minutes
•
Nalmefene: onset 1-2 minutes IV, 5 minutes IM, duration of action 1-2 hours
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Anticholinergics are sometimes used in preanesthetic combination to prevent bradycardia and decrease salivary secretions. Drug
class effects include secretion reduction, bronchodilation, arrhythmias (glyco is less arrythmogenic), thickening of respiratory
secretions, and inhibition of intestinal peristalsis. Conservative use of anticholinergics is recommended and their use should never be a
substitute for diligent monitoring.
Induction Drugs consist of injectable agents that allow the anesthetist to induce anesthesia quickly and to secure an airway.
Injectable agents provide a safer, less stressful alternative to ‘gassing’ or ‘boxing’ down a patient. It is also less expensive, faster, with
less waste/pollution and more control. All injectable anesthetics depress some vital organ function making the use of preanesthetics
and subsequent lower doses essential.
Dissociative anesthetics are also referred to as cyclohexamines- these drugs produce a dissociated state along with sympathetic
stimulation. Increases in cerebral blood flow and intracranial and intra-ocular pressure, CNS stimulation, primary cardiovascular
depression with indirect sympathetic stimulation leading to increased heart rate, blood pressure and cardiac output. Sub-anesthetic
doses of ketamine (and possibly Telazol) act as NMDA antagonists blocking central sensitization (wind-up pain) in the dorsal horn
of the spinal cord. They are not analgesics in and of themselves and should not be used as a sole means of pain control however;
ketamine is a great adjunctive medication contributing to a balanced approach to analgesia. Ketamine and Telazol are contraindicated
in in patients that are sympathetically spent- severe trauma, stress, shock etc. This is due to the fact that only the direct cardiovascular
effects will be appreciated. Not recommended for use in patients with cardiovascular disease, head trauma, intracranial masses,
glaucoma, corneal ulcers, pheochromocytoma, hyperthyroidism.
Ketamine: dissociative anesthetic that causes muscle rigidity when used alone, commonly coupled with a benzodiazepine for
induction. Not recommended for use with an anticholinergic as significant tachycardias can ensue, hepatic metabolism in the dog,
renal excretion in the cat.
Telazol: Combination of a dissociative and a benzodiazepine. Tiletamine and zolazepam mixture, must be reconstituted with
saline, use within 4 days if stored at room temp or two weeks if refrigerated.
Propofol and Propofol-28: Propofol is an ultra-short acting non-barbiturate induction drug with rapid metabolic clearance. Ninety
seconds to peak effect and 5 minutes to redistribute, non-cumulative, administer slowly and steady to avoid over-dosing. Propofol has
the potential to cause profound cardiovascular and respiratory depression and should be used cautiously. IV injection can be painful
and muscle twitching and seizure-like activity has been reported. Repeated dosing is not recommended in cats as oxidative injury to
red blood cells may result. Drug can be re-dosed intraoperatively at 1-2 mg/kg if patient becomes light. Pre-oxygenation is also
recommended. Propofol-28 contains benzyl alcohol as a preservative giving it a 28-day shelf life. Regular propofol should be
discarded 6-8 hours after opening.
Etomidate: Etomidate has little to no negative effect on the cardiovascular system- ideal induction drug for hemodynamically
unstable patients. It may have brain protective properties after global ischemia, and inhibits steroid production by the adrenal glands
for 3-6 hours after administration- not recommended in patients with hypoadrenalcortism. Vomiting and retching is common with
underdosing and etomidate can be painful IV because it is based in propylene glycol. This drug is also expensive.
Alfaxalone: Alfaxalone is a neuroactive steroid substance that is used extensively in the UK, Australia, Europe and Canada. It
produces hypnosis with reasonable muscle relaxation and a decrease in cerebral blood flow and cerebral oxygen demand. Dose
dependent hypotension may be seen initially due to myocardial depression and peripheral vasodilation but the effects are often offset
by the reflex tachycardia. Respiratory depression associated with the use of alfaxalone is dose dependent; the drug is non-cumulative
and approved for IV use only. IM chemical restraint is off-label and works better for cats vs. dogs (very short duration of action).
Alfaxalone is not an analgesic, it does not contain preservatives and should be discarded 6 hours after opening.
Maintenance of anesthesia is often achieved through the use of inhalant anesthetics. Inhalants are potent vasodilators and cause
dose-dependent hypotension and respiratory depression. The two most common inhalants used in veterinary medicine are isoflurane
and sevoflurane. The minimum alveolar concentration or MAC is the potency of an inhalant. MAC-50 is the amount of inhalant
needed to keep 50% of patients non-responsive to surgical stimulation. MAC-95 or surgical MAC is the amount of inhalant needed to
keep 95% of patients non-responsive to surgical stimulation and is calculated by multiplying MAC-50 for the species by 1.5. It is
important to note that respiratory arrest can occur at 2 x MAC so proper dosing is essential to safety. MAC studies are done on
patients who have not been given pre-anesthetics. The use of pre-anesthetics decreases the amount of inhalant necessary thereby
reducing MAC.
Isoflurane: MAC is 1.3% in dogs and 1.6% in cats, low blood-gas solubility (rapid induction and recovery), 0.2% metabolized in
the body. Sevoflurane: MAC is 2.3% in dogs and 2.6% in cats (sevo is less potent and requires higher vaporizer settings to maintain
anesthesia), lower blood-gas solubility, 3% metabolized in the body.
Pain Management is an important part of the anesthetic protocol and balanced techniques should be employed whenever possible.
In addition to opioids and alpha-2 agonists, the flowing drugs should augment the pain management protocol.
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Non-steroidal anti-inflammatory drugs (NSAIDS)
NSAIDS (Non-steroidal anti-inflammatory drugs) block the production of specific prostaglandins by binding and inhibiting the
cyclooxygenase (COX) enzyme. COX enzymes (COX-1 and COX-2) also have important homeostatic functions. COX-1 mediates
prostaglandins responsible for renal and GI blood flow and platelet integrity and COX-2 mediates prostaglandins responsible for
inflammation, pain, edema, fever as well as other homeostatic functions. NSAIDS should be avoided in animals with renal or hepatic
dysfunction, coagulopathies, GI disorders, shock, hypotension/hypovolemia and they are not recommended for use in combination
with corticosteroids.
Lidocaine
Lidocaine is a local-anesthetic and anti-arrhythmic agent with a rapid onset and short duration of action. Lidocaine is a prokinetic that
enhances gut motility and help prevent ileus. It has MAC sparing effects when given as a constant rate infusion, a loading dose must
be given prior to starting a CRI to achieve blood levels. Cats are sensitive to lidocaine and care should be taken when this drug is used.
MLK (Morpine, Lidocaine, Ketamine)
Drugs are combined into a bag of IV fluids and delivered at a surgical rate. Loading dose of each drug is required to achieve
therapeutic levels.
Tramadol
An oral medication that has weak mu receptor effects along with norepinephrine and serotonin reuptake inhibition. Tramadol works
well with NSAIDS as post-operative pain management. Gabapentin is effective at reducing hyperalgesia and allodynia associated
with neuropathic pain and central sensitization as well as chronic and malignant pain. Gabapentin is not an analgesic but an adjunctive
medication that allows true analgesics to work better by calming down the nervous system- gabapentin should be used in conjunction
with NSAIDS and/or tramadol for best results. Amantadine is an NMDA antagonist and analgesic adjunctive medication. It is good at
reducing central sensitization. Amantadine is excreted almost unchanged in the urine- reduce doses in the renal patient.
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Lights Out!
The Anesthetic Induction Period
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
Anesthesia is the reversible loss of sensation as a result of pharmacological agents that may affect all or part of the body. There are
differing levels of anesthesia that range from conscious sedation for minor procedures to deep general anesthesia for more invasive
techniques. Anesthesia induction precedes general anesthesia that produces unconsciousness and through balanced techniques also
includes analgesia, muscle relaxation and amnesia.
Balanced anesthesia
Balanced anesthetic protocols incorporate multiple drugs and techniques from different classes to achieve a desired goal. Animals are
prepared for anesthesia by performing a thorough patient evaluation, choosing adequate premedication, placing an IV catheter,
initiating a controlled induction and securing the airway. The equipment and drugs used in the induction period vary depending on the
patient’s health and temperament as well as the procedure being performed. The anesthetist’s role is to gather this information and in
consultation with a veterinarian, develop a suitable induction plan for his/her patient.
Anesthesia induction
The careful administration of appropriate agents to bring about unconsciousness and to help facilitate endotracheal intubation or
securing of the airway. The induction period begins with premedication administration and ends when all monitors are connected and
the patient is on a maintenance level of anesthesia.
Getting ready
Once the patient has been premedicated, time is needed for the drug to take effect. The amount of time depends on the route and type
of drug as well as the temperament of the patient and the environment. IV premeds require 1-2 minutes where as an IM injection may
take up to 15 minutes to take effect. Anxious patients will often take longer to sedate and patients premedicated in a loud or otherwise
stressful/active room will also be on edge and take longer to sedate. Best practice is to premed and then put the patient in a quite and
dark room. Periodic monitoring of patients while sedating is essential. The period of time between premeds and induction is an ideal
time to gather supplies and leak test equipment. For example one could:
•
Set up and pressure test anesthesia machine
•
Gather IV catheter supplies
•
Choose three endotracheal tubes and check each cuff for leaks
•
Corral monitoring equipment and check that it is working properly
•
Plug in supplemental heating device and warm it up
•
Fill out anesthesia monitoring sheet with patient information
•
Calculate, check and draw up induction drugs
•
Calculate fluid rate and set up fluids
•
Formulate an emergency plan and calculate emergency drugs
IV catheters
All patients undergoing anesthesia should have an IV catheter placed. IV access is essential when performing successful anesthesia
because having a catheter facilitates the delivery of IV anesthetics, avoids potentially harmful perivascular drug administration and
provides access to rapid drug/fluid administration in emergency situations. IV fluid therapy in anesthetized dogs and cats is
recommended to maintain venous access, to help correct hypovolemia caused by the vasodilitory effects of anesthetic drugs, to help
replace insensible fluid losses common in the surgical patient.
IV catheter size is important because it influences the drug delivery rate and may cause unwanted patient side effects. For example,
a small gauge catheter is easy to place and produces less inflammation; however, it may be difficult to deliver highly viscous drugs
rapidly or with ease. The IV fluid administration rate is also limited by the internal diameter of the catheter. A larger gauge catheter
may be more difficult to place but will deliver drugs and fluids with ease. It can cause phlebitis due to the constant contact it makes
with the vessel wall. As a general guide, 22 gauge catheters work well in most cats and 20 gauge catheters work well in most dogs.
Gauge is a decending scale; large numbers correlate to small diameters (20 gauge is smaller than 10 gauge). French is ascending
where large numbers correlate with large diameters (20 French is larger than 10 French).
Note: Intact animals, male and female, have tougher skin and often require a larger sized catheter or a ‘pilot’ hole to be made with
a needle prior to catheter insertion. This hole prevents burring of the cannula from pushing it through tough tissue. To make a pilot
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hole, choose a needle one size larger than the catheter you wish to place. Tent up the skin and poke a hole through the skin only. Then,
use that hole to introduce the catheter and stylet through the skin and then proceed by placing the catheter into the vein.
Induction drugs
Induction is best achieved through IV administration of a drug because this route allows for rapid airway control and enables careful
titration to provide the desired effect without over dosing.
The ideal induction agent would have a wide therapeutic index, rapid onset of action, quick metabolism or redistribution, no
negative affect on other body systems (maintains respiratory drive), reversible, inexpensive, long shelf-life, and not be a controlled
substance. This drug does not exist but a few come relatively close.
Ketamine/midazolam
This combination is a dissociative anesthetic (ketamine) coupled with a benzodiazepine (midazolam). Ketamine causes muscle rigidity
whereas the benzodiazepine provides muscle relaxation.
Pros
This combination increases heart rate and blood pressure as a result of sympathetic nervous system stimulation. Ketamine antagonizes
the NMDA receptor (an excitatory neurotransmitter in the brain) effectively blocking glutamate and stopping the amplification of pain
signals. Induction is fast and drug is titrated to effect.
Cons
This combo can cause an increase in cardiac work and myocardial oxygen demand. In critical patients with depleted sympathetic
reserve ketamine can drop cardiac output and blood pressure. The acidic pH of ketamine makes IM injections painful. This
combination should be avoided in patients with a seizure history or history of head trauma, brain lesions, tumors and ocular disease
and it can increase intracranial (ICP) and intraocular pressure (IOP).
How to use
A dose of ketamine is calculated based on the patient’s lean body weight. The volume of ketamine is matched by an equal volume of
midazolam (or diazepam). Half of the calculated dose is given IV over 30-90 seconds then titrated to effect (until patient is able to be
intubated).
Notes
Induction with ketamine/midazolam is slower than with propofol and patients will maintain more muscle and jaw tone. This is
important to keep in mind to avoid over-dosing. Ketamine takes about 2 minutes to reach the brain and lasts about 20 minutes.
Ketamine is a CIII controlled substance.
Telazol
This drug is a dissociative and sedative combination similar to ketamine/midazolam. The drugs in Telazol are tiletamine and
zolazepam. This drug is reserved for induction of healthy dogs and cats as it cannot be tailored to meet the needs of the patient, it is
not reversible and it has a relatively long duration of action. Telazol is a CIII controlled substance.
Propofol
A commonly used short-acting IV anesthetic with a relatively short shelf life.
Pros
Propofol is non-cumulative and it provides a rapid, smooth induction with a short duration of action. It can be used as a constant rate
infusion (CRI) or total intravenous anesthesia (TIVA) in dogs or redosed via low-dose injections for procedures like a laceration
repair, minor biopsies and endoscopy. It is good for head trauma as it doesn’t increase ICP and c-sections as it has minimal effects on
fetus.
Cons
Propofol can cause significant respiratory depression, apnea and cyanosis which is more pronounced when the drug is administered
rapidly or in large doses. Animals given propofol must be monitored closely and supported (assist respirations to avoid hypoxemia).
Propofol is highly protein bound so patients with hypoproteinemia will require lower doses. It is not currently a controlled substance.
How to use
Propofol should be calculated as a range giving the anesthetist the information necessary to dose appropriately. Depending on how
sedate the patient is, a dose within the range is given as a slow IV push over about 20 seconds (low end for very sedate and mid-range
for less sedate patients). The patient is assessed and the drug is titrated to effect, e.g. until intubation is easily achieved. Propofol takes
about 90 seconds to reach the brain and then about 5 minutes to redistribute making it important to be ready but also be a bit patient.
Alfaxalone
Alfaxalone is a neuroactive steroid molecule, with central effects. Despite being an analogue of progesterone, Alfaxalone does not
bind to sex hormone, glucocorticoid, or mineralocorticoid receptors
Pros
This drug provides a rapid induction and hypnosis with reasonable muscle relaxation and a decrease in cerebral oxygen demand. It is
not irritating perivascularly, it has a wide safety margin, smooth induction and rapid but smooth recovery. It is non-cumulative and
can be dosed daily.
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Cons
Dose-dependent respiratory depression and hypotension from myocardia depression and peripheral vasodilation that is offset by a
reflex tachycardia.
How to use
A dose is calculated based on lean body weight and given IV over 60 seconds until the signs of anesthesia are appreciated, then it is
titrated to effect. Rapid admin exacerbates side effects. Alfaxalone is a CIV controlled substance.
Etomidate
A short-acting injectable based in propylene glycol.
Pros
It is rapidly metabolized by the liver and plasma esterases (enzyme found in the plasma that cleave apart compounds and make them
inactive) leading to a quick recovery. It produces minimal cardiovascular and respiratory depression and does not alter heart rate,
cardiac contractility or blood pressure. This drug is a great choice for high-risk patients including those with pre-existing cardiac
conditions and hepatic disease; it is not a controlled substance.
Cons
High cost, retching and myoclonus if patient is not adequately sedated or if it is underdosed, may cause pain on injection. Drug can
inhibit steroid production for up to 4 hours.
How to use
Calculate dose based on lean body weight and administer the entire calculated dose as a slow IV push to well sedated patients.
Opioid
Opioids can be used to induce anesthesia is sick or debilitated patients.
Pros
Gentle and relatively safe induction as there is little negative effect on cardiovascular function.
Cons
Patients become very noise sensitive during this time so a quite induction area is essential. This method is really only useful in very ill
or old patients that may not tolerate the cardiovascular effects of other induction agents.
How to use
A combination of an opioid and a benzodiazepine are given IV until patient is unconscious.
Inhalants
Inhalant anesthetics can also be used to induce anesthesia; however, mask or chamber inductions are stressful, airway control is slow
and there is a great risk for contamination of the work environment. Over dosing of inhalant anesthetic during a mask or chamber
induction is nearly always a given. Isoflurane and Sevoflurane are the two inhalants used with greatest frequency in veterinary
medicine. Both have high vapor pressures requiring a precision vaporizer for delivery and low blood:gas solubility (the measure of the
tendency of an inhalant to exist as a gas or dissolved in blood) making induction and recovery quick. The biggest differences between
isoflurane and sevoflurane is their minimum alveolar concentration or MAC. MAC is the minimum concentration of drug in the lungs
that is needed to keep 50% of patients immobile during surgical stimulation. It is used to discuss the relative ‘strength’ of the inhalant.
Those with a lower MAC are more potent because less drug is needed to achieve the same effect. MAC is also used to help guide
vaporizer settings.
Pros
Provides a relatively rapid induction and recovery with good muscle relaxation. The drug is eliminated primarily via the lung with
little kidney and liver metabolism.
Cons
Dose-dependent central nervous system depression, dose dependent hypotension, myocardia depression and respiratory depression.
Inhalants do not provide any analgesia and should never be used as the sole agent for painful procedures. There is also a risk of
exposure to potentially harmful waste anesthetic gas. Inhalants are not safer than properly used injectable drugs.
How to use
MAC is used to guide the vaporizer setting for intubated animals and other drugs (adjuncts and premeds) are used to help keep the
vaporizer setting as low as possible to avoid the negative dose-dependent side effects.
A patient’s response to IV anesthetic induction will depend on the rate of administration (most anesthetics agents are titrated to
effect) and over dosing is more likely when drugs are given too quickly and their side effects are not appreciated as they happen.
Physiologic factors such as blood volume, total protein levels and blood pH play a role in the distribution of drugs throughout the
body. The overall health status and organ function will affect how quickly the drug is distributed, metabolized and excreted which
ultimately effects when and how long those effects last. Animals that are ill or debilitated in some way, including advanced age will
require less induction drugs than their healthy counterparts. Premedications and the patient’s response to them will also influence the
type and amount of agent needed. Using premedications will reduce the amount of induction drug need and thus further reduces
unwanted side effects. As an added bonus, premedications make IV catheter placement easier and less stressful for the patient and the
staff.
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Endotracheal tubes and intubation
There are three methods of selecting the proper sized endotracheal tube. One involves using the width of the nasal septum as a guide,
another uses a chart with the animal’s lean body weight and recommended endotracheal tube (ETT) size and finally palpation of the
outer diameter of the trachea in the region of the mid-neck. The most accurate way to choose a tube is lean body weight and breed.
Choose three tubes, the size you expect to place plus one half size smaller and one half size larger. If intubating a brachycephalic
breed, choose 2 sizes smaller since these breeds often have stenotic or narrow tracheas. Measure the length of the tube alongside the
patient so that the tip of the tube lies midway between the larynx and thoracic inlet. ETT tubes that are too short may not pass through
the larynx and those that are too long may pass into a bronchus resulting in ventilation of only one lung. If the tube extends more than
1 inch passed the incisors, it should be trimmed or a shorter tube should be used. Long tubes that stick out passed the incisors
contribute to mechanical dead space that may lead to the rebreathing of carbon dioxide.
Intubation should be performed using the largest sized tube possible to minimize the need to overinflate the ETT cuff. A
laryngoscope should be used to allow visualization of the larynx and to get the user used to handling the equipment for when it is
needed for a challenging or emergent intubation. Sterile lubricant should be lightly smeared on the ETT cuff to help facilitate
intubation and to help form a seal within the trachea. Lidocaine is helpful in desensitizing the larynx in cats. Cuff inflation after
placement should be done with care.
Complications of endotracheal intubation
Esophageal intubation
Inadvertent placement of the ETT into the esophagus.
Clinical signs
Absence of EtCO2 readings, patient will not maintain unconsciousness, inability to achieve a proper seal.
Treatment
Tube should be deflated, removed from esophagus and then placed into the trachea
Bronchial intubation
Intubation of one of the mainstem bronchi due to an excessively long ETT.
Clinical signs
Low pulse ox reading from one lung ventilation, difficulty keeping patient asleep
Treatment
Deflate cuff and gently pull ETT tube back so that the tip falls midway between the larynx and thoracic inlet. Use an ET tube of the
same length to determine the length of the ET tube inside the patient.
Laryngospasm
Reflexive closure of the laryngeal cartilage usually from stimulation and inadequate anesthetic depth. Common in cats.
Clinical signs
Closed laryngeal cartilage and inability to place endotracheal tube.
Treatment
Desensitize laryngeal cartilage by placing a drop of lidocaine onto the area. Alternatively, deepen the plane of anesthesia to suppress
the reflex. Do not continue to push the ET tube towards the laryngeal cartilage without first desensitizing it or deepening the level of
aneshteisa as it will only make the spasms worse.
Forceful intubation
Endotracheal intubation should be gentle and easy. Although the largest sized tube should be placed, do not forcefully attempt to place
a tube that is larger than necessary. Damage to delicate tissues at the back of the throat can lead to edema and potential airway
obstruction.
Clinical signs
Red or swollen laryngeal tissues, difficulty breathings upon extubation, complete airway obstruction.
Treatment
If patient is having difficulty breathings post extubation it may be necessary to re-anesthetize them and place another endotracheal
tube (smaller). Provide the patient with supplemental oxygen and try to keep them calm, be ready to intubate with a much smaller
tube.
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Monitoring Without Monitors
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
Anesthesia literally translates into “without sensation”. Our goal as anesthetists is to provide unconsciousness, amnesia, analgesia and
muscle relaxation for a variety of procedures both invasive and non-invasive. Our ability to carefully string our patients out along the
line between consciousness and unconsciousness compromises homeostasis making close monitoring essential.
Why monitor?
Anesthetic emergencies are difficult to predict especially if the patient is not being monitored. Anesthetic emergencies can happen
quickly and they can be devastating. It is better to be proactive rather than reactive when it comes to anesthetic complications. Our
goal is to be able to walk that line with confidence by maximizing the safety of the anesthetic experience. There is no safe anesthesia,
only safe anesthetists.
Morbidity and mortality (M&M)
Morbidity refers to the prevalence of complications occurring secondary to hypoxia. Mortality is the rate of anesthetic related deaths.
Certain complications are more likely to increase morbidity and mortality:
•
Excessive bradycardia
•
Cardiac depression
•
Vasodilation
•
Hypotension
•
Arrhythmias
•
Hypoventilation
•
Hypoxemia
•
Hypothermia
These obstacles all make it difficult for nutrient rich oxygen to reach the tissues. Diligent monitoring allows us to recognize and
treat these potentially life threatening problems.
Monitoring basics
According to the American College of Veterinary Anesthesia and Analgesia (ACVAA) guidelines on anesthesia, continuous
awareness of the heart rate and rhythm along with the gross assessment of peripheral perfusion including pulse quality, mucous
membrane color and capillary refill time are mandatory. Ventilation and oxygenation, anesthetic depth and body temperature are also
important. If you didn’t have any monitors, you could still gather information using your eyes, ears and hands: Heart rate, pulse
quality and vasomotor tone, respiratory rate and character, reflexes and tone, eye position and body temperature. Monitoring multiple
parameters gives you a more complete picture of the physiologic status of the patient.
Heart rate
Be aware of the normal heart rate range for the species you are working with as well as what is normal for the breed and the
individual. Give yourself a range that is specific to this patient and stay away from extremes. Bradycardia is an excessively slow heart
rate that affects cardiac output and leads to hypotension and poor perfusion. For most medium to large-breed dogs, the low 50’s with a
normal blood pressure is often tolerated. Smaller dogs have higher resting heart rates as do cats so for this population the tolerated low
for small dogs might be 80 bpm and for cat 120 bpm. When possible, also monitor blood pressure and end-tidal carbon dioxide for the
most complete cardiovascular picture.
Tachycardia is an excessively fast heart rate that affects cardiac output. The less time the heart spends in diastole, the less time it
has to fill with blood so blood pressure is often affected by way of a decrease in stroke volume. Tachycardia also increases myocardial
oxygen consumption and makes the heart have to work extra hard. Depending on the size of the patient and their normal resting heart
rate, tachycardia in the dog is often in excess of 160-180 bpm and 240-280 bpm in the cat.
Some causes of extremes of heart rate (and potential ways to remedy them)
Bradycardia
•
Anesthetic overdose (lighten up)
•
Opioid administration (give an anticholenergic)
•
Alpha-2 agonist administration (reverse or no treatment)
•
Hypothermia (rewarm)
•
Hypoxia (oxygen therapy)
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•
1st and 2nd degree A-V blockade (anticholenergics)
•
High vagal tone (anticholenergics)
Tachycardia
•
Too light (deepen)
•
Painful (give analgesics)
•
Ketamine administration (no treatment)
•
Anticholenergics (decrease dose next time)
•
Inotropes (decrease infusion)
•
Hypovolemia (restore volume)
•
Hyperthermia (cool)
•
Hypoxemia (oxygen therapy)
•
Hypercarbia (ventilate or eliminate rebreathing of CO2)
•
Anesthesia recovery (comfort or no tx)
Pulse quality and vasomotor tone
Palpation of a pulse is a subjective way of approximating blood pressure. It is done by evaluating the height and width of the pulse
pressure waveform compared to normal. Bounding pulse- vasodilation as seen in sepsis and hypovolemia, where the vessel is easily
collapsible. Weak and thready pulse- vasoconstriction as seen with alpha-2 administration, poor cardiac function, tachycardia, small
stroke volumes. It is essential that the anesthetist palpate normal pulses in a variety of patients to make it easier to determine when a
pulse is abnormal.
Pulse quality is largely a reflection of stroke volume (the volume of blood pumped with each beat) and vessel size or vasomotor
tone (the degree of vasodilation or vasoconstriction). Vasomotor tone regulates both peripheral and visceral perfusion. Vasodilation
improves peripheral perfusion but can cause hypotension if too severe. Vasoconstriction can impair peripheral perfusion but also
improves blood pressure. Assessing vasomotor tone can be done by evaluating mucous membrane color and capillary refill time.
Normal mucous membrane color consists of a light to medium pink color and a capillary refill time of 1-2 seconds. Pale mucous
membranes may indicate vasoconstriction (think about the pale gums of an animal given dexmedetomidine). Red mucous membranes
may indicate vasodilation (think about a patient that is hyperthermic or too deeply anesthetized).
Many things can cause vasodilation or vasoconstriction and the way to correct it is to address the cause.
•
Vasodilation
o Systemic inflammation
o Sepsis
o Hypercapnia
o Hyperthermia
o Drugs (acepromazine, inhalants)
•
Vasoconstriction
o Hypovolemia
o Heart failure
o Hypothermia
o Drugs (alpha-2 agonists, sympathomimetics)
Pulse sites
Pulses can be assessed from a variety of sites and each site offers a little different feel. It is essential for the anesthetist to become
familiar each site. The femoral artery is located high up on the inner thigh where the leg meets the abdomen. This vessel is large and
easy to palpate in most patients but can be challenging to find in obese or heavily muscled animals. The dorsal metatarsal artery is
located on the dorsal aspect of the hind limb distal to the hock and over the metatarsals. This vessel is very accessible and great for
arterial catheter placement. It can be difficult to palpate in vasoconstricted, hypotensive or small patients. The coccygeal artery is
located on the proximal ventral tail is also used for arterial catheter placement. The radial artery is just proximal to the metacarpal pad
on the forelimb and a bit medial. Because it is located distally on the limb, it too can be difficult to palpate in vasoconstricted,
hypotensive or small animals. The lingual artery is on the ventral portion of the tongue near the lingual frenulum. It is only useful in
anesthetized animals and is a great place to easily grab a pulse intra-operatively. In exotics, cats and small dogs, placing your hand
around the chest is another way to feel the heartbeat.
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Respiratory rate and character
All anesthetic drugs provide some degree of respiratory depression making respiratory monitoring and support vital. A change in
breathing is a good indication of a change in patient status. Respiration is comprised of tidal volume (TV), respiratory rate (RR), and
minute volume (MV).
•
TV (Vt) = the volume of air in a single breath (10-20 mL/kg)
•
RR (f) = the number of breaths per minute (8-15 br/min)
•
MV (V) = total volume of air breathed per minute (150-250L/kg/min)
•
TV X RR = MV
Respiratory character describes the quality of the breaths being taken. Breaths can be shallow, deep, slow, fast, irregular or absent.
Shallow breaths are often associated with a small tidal volume and they tend to be faster than normal breaths. The increase in rate
makes up for the decrease in volume and normalizes the overall amount of air moved in one minute (minute ventilation). Deep breaths
are characterized as having a large volume but slow rate. Apnea is the absence of spontaneous breathing and is common especially
after induction of anesthesia. It is important that the anesthetist support the patient through this time by breathing for them until they
can begin to breathe on their own. Bradypnea is a slow respiratory rate and without an end-tidal carbon dioxide monitor or blood gas
analyzer, it is difficult to determine if these patients are adequately ventilating. Hypothermic patients and those that are a deep level of
anesthesia will often exhibit this slow respiratory rate. Tachypnea is an increased respiratory rate with a number of possible causes:
too light, too deep, hypoxia, hypercapnia, hyperthermia, hypotension, painful, septic, atelectasis etc. It may be helpful to give some
larger breaths, check body temp, check BP, assess pain, assess anesthetic level etc to find the cause.
Ventilation is defined as the act of breathing and respiration is the actual gas exchange. The adequacy of ventilation and
appropriate gas exchange can really only be determined through arterial blood gas analysis or end-tidal carbon dioxide measurement.
Reflexes and tone
The amount of muscle tone an animal has and whether or not their reflexes are present (and to what extent) gives the anesthetist an
indication of the depth of anesthesia. The presence of reflexes indicates a lighter level of anesthesia but this is not always a bad thing.
Brisk reflexes indicate that the patient is too light, but sluggish reflexes are ok as long as it doesn’t interfere with the procedure. The
corneal reflex should always be present (unless paralyzed).
Tone can be assessed simply as none, some or lots. Jaw tone, anal tone and general muscle tone should be taken into account when
assessing the depth of anesthesia. No tone may indicate that the patient is a little deep or adequately anesthetized; some tone is ok and
even good as long as it doesn’t interfere or cause harm but lots of tone is not good unless you are trying to recover the patient.
Eye position
The eye is a little window into the central nervous system and its position can tell us a lot about how deeply our patients are
anesthetized. If the eye is centrally facing the animal is either too deep or too light so it is important to also look at pupil size. A
medium pupil indicates that the patient is light. A dilated pupil indicates a deep level of anesthesia and an immediate adjustment is
necessary. A constricted pupil also indicates a deep level of anesthesia and an immediate adjustment is necessary. If they eye is in a
ventral-medial position, the patient is at a good plane of anesthesia. Keep in mind that drugs can affect eye signs and pupil size
making it important to assess the patient after pre-medication and before induction (opioids cause dilation; ketamine can affect the
palpebral reflex etc).
Temperature
Anesthesia depresses muscle activity, metabolism and thermoregulation and leads to hypothermia. A good temperature range is 98102 degrees Fahrenheit in dogs and cats perianesthesia. Hypothermia can contribute to an anesthetic overdose making necessary to
decrease your doses in hypothermic patients! Animals less than 98 degrees Fahrenheit are considered hypothermic. Mild hypothermia
is anywhere from 96-98 degrees Fahrenheit, moderate is 94-96, severe is 90-94 and anything less than 90 degrees is moribund due to
CNS depression and imminent death if not corrected. Patients greater than 103.5 degrees Fahrenheit are considered hyperthermic
(normal being 100.5-102.5). Cell damage occurs once the body temperature reaches 108 degrees.
YOU
Your eyes, ears and hands can make excellent monitors if you know how to put them to work!
Remember to be vigilant and look at the whole picture (co-existing disease, drugs given and currents meds, procedure, species,
breed…). Seek knowledge, the more you know the more you know the more confident you will be. Remember to enjoy yourself,
anesthesia is an art and a science and it can be fun.
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On PAR:
Perils of Postanesthetic Recovery
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
The recovery phase begins once the procedure ends and anesthesia ceases to be delivered. This may include turning off the inhalant or
discontinuing total intravenous anesthesia (TIVA). Recovery ends when the patient is sternal, alert, extubated and normothermic.
It is good practice to maintain the patient on 100% oxygen for 5 minutes after discontinuing inhalant. It is also common to
disconnect the patient from the breathing system, occlude the patient end of the hoses and flush the system full of 100% oxygen then
reconnect to the patient.
•
Patients continue to be respiratory depressed and can benefit from an enriched oxygen mixture
•
Waste anesthetic gas is corralled and disposed of decreasing exposure to personnel
Monitoring
Patients should continue to be monitored during the recovery period and the extent to which they are monitored depends on their
overall condition.
•
The ECG patches can be removed unless patient has a history of arrhythmias. Patients that have undergone major
surgery like a splenectomy, GDV, pericardectomy, PDA ligation etc. should have the ECG maintained through recovery
and likely post-operatively as well to check for arrhythmias. The most likely arrhythmias would be VPC’s but may
progress to V-tach and negatively affect blood pressure.
•
The blood pressure cuff can be removed if the patient has been stable and normotensive. Patients that have been
hypotensive or cases where blood pressure needs to be monitored closely (renal transplant) should continue with
readings. Most patients’ blood pressure will increase once the inhalant is discontinued and they start to recover making
it acceptable to discontinue this monitoring parameter. Blood pressure lines and ECG monitors can make it difficult to
transfer patients to gurneys and recovery cages so these monitors are some of the first to be removed.
•
The pulse-oximeter should be maintained at least until the patient is extubated. This monitor is easy to place and
maintain and is often hand-held making it simple to continue to use. Also, it will alert the anesthetist to hypoxemia- a
condition that is likely after discontinuation of oxygen in the face of continued respiratory depression.
•
Continue to monitor EtCO2 until disconnected from oxygen or extubated. Continued respiratory depression is common
during recovery and hypoventilation will be reflected in the EtCO2 readings giving the anesthetist the opportunity to
assist respirations and help ward off hypoxemia.
•
Maintain supplemental heating if patient is normo- or hypothermic. Patients can lose heat during recovery because they
are no longer under drapes and such. The temperature should be taken immediately post-op and then every 30 minutes
until patient is able to maintain a normal temperature for two consecutive readings.
•
Some patients may become hyperthermic during recovery from anesthesia and these patients need to be monitored more
closely and steps may need to be taken to reduce their temperature. Ways to this may include just removing
supplemental heat, removing blankets, wetting down paws (alcohol is not recommended) or placing a wet towel in a
cage with a patient. Acepromazine promotes vasodilation and may help bring the body temperature down. NSAIDS can
help if the hyperthermia is actually pyrexia secondary to inflammation. Post-operative infections will not manifest
immediately, it takes a day or so for the bacteria to gain a foothold so this should not be a consideration unless infection
was present pre-operatively. Opioid induced hyperthermia is self-limiting and doesn’t typically require intervention.
Nursing care
Good nursing care in recovery can have a dramatic positive effect on anesthesia recovery and post-operative comfort. Provide patients
with a quiet and comfortable place to recover, keep them warm, express their bladder and offer food/water when awake. Hunger,
hypoglycemia, hypothermia and a full bladder are all uncomfortable situations and can exacerbate pain and cause undue stress. Some
patients will benefit from having cotton put into their ears to muffle outside noise and blanket over their cage to shield their eyes from
the ambient light. Soft music (through a dog’s ear) and items from home (unwashed so they smell like home) are also comforting.
When working with a post-op patient, be patient, go slow and narrate what you are doing to help calm the patient and to keep you
calm as well.
Pain management may include a constant rate infusion (CRI) or intermittent boluses of opioids, placement of a cold pack over the
incision, massage of tense muscles or those strained during surgical positioning, and anxiolysis. Other steps that can be taken to
increase comfort include cleaning off any left over scrub solution or blood from the surgical site. Blood and scrub can be itchy and
their presence may prompt patients to bother the surgical site. Gently remove this with saline or water during recovery.
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Patients that are hypothermic can be placed on a soft, insulated surface with a forced warm air heating blanket and a blanket over
top that gets tucked under the patient or the pad creating a bubble of warm air. This bubble shouldn’t be disturbed unless necessary to
check body temperature. If IV fluids are being given they can be warmed near the patient so heat is not lost between the source and the
patient. Once the patient is able to maintain their body temp above 99 F, the supplemental heat can be removed. Once removed, the
body temp should be checked in 30-60 minutes to make sure it is maintaining.
Recovery area and extubation
Recovery should be smooth and stress-free and it should take place in a quiet area of the hospital where the lights can be dimmed as it
is important to minimize unnecessary stimulation during recovery. Vitals signs such as HR, RR, CRT and MM color should be
monitored every 5-10 minutes during recovery and body temperature every 30 minutes. SpO2, EtCO2 and BP/ECG can also be
monitored and should be if the patient is recovering from a major procedure or is compromised in some way.
A full recovery is defined as the point at which the patient is able to sit sternal with normal vital signs (HR, RR, body temp).
Patients should be extubated when they are ready and showing signs which include alertness, swallowing and tongue tone. Patients do
not have airway control until they are alert and able to swallow so these parameters are used to decide when it is safe to remove the
endotracheal tube. Although massage and mild stimulation can be helpful is rousing patients, aggressive waking is contraindicated as
it can lead to patient and staff injury. Recovering animals should be aloud to ‘sleep it off’ especially after a long or painful procedure.
Some animals pop awake and start to chew on the tube, (these patients should be extubated quickly!) while others are content being
able to breathe (brachycephalics). Do not deflate the endotracheal tube cuff until you are ready to extubate since vomitus or other fluid
may be present in the pharynx and can be easily aspirated. Brachycephalic breeds will be alert, sternal and content with a tube in their
mouths- these recoveries take a bit longer but these patients can be extubated when they are alert and sternal. Some patients will not be
alert but will be swallowing slightly- these patients are not ready! Wait for alertness and tongue tone before pulling the tube unless
instructed otherwise. Cats should be extubated as soon as possible as they are prone to laryngeal spasm upon extubation. After
extubation patients should be watched closely every 15-20 minutes until a full recovery has been achieved- hypoventilation can
quickly lead to hypoxemia when a respiratory depressed animal is breathing room air. The IV catheter should remain in place until full
recovery and pain has been properly addressed. Catheters kept in over night should be wrapped and kept clean.
Post-operative pain management
Pain should be assessed as soon as the patient is conscious. Review the anesthesia record to gather information on which analgesics
have been given and when. Additional analgesics should be given during recovery if the patient is due for them or if they are showing
signs of pain. Pain can be assessed using any number of different pain scoring sheets including: University of Melbourne Pain Scale,
Glasgow Composite Measure Pain Score or the Colorado State University Acute Pain Scale (author recommendation). Pain should be
evaluated every hour for the first 4-6 hours following surgery and then regularly until discharge. High quality pain management
should be instituted for at least the first 24 hours post-op and may continue if necessary. High quality means opioids plus NSAIDS (if
tolerated) plus or minus sedation or adjunctive medications along with good nursing care.
To go home medications for pain management
TGH meds: 3-7 days of analgesia depending on the type of procedure. PO drugs like tramadol, NSAIDS, gabapentin and amantadine
are common. Certain opioids like fentanyl patches or buprenorphine can also be sent home because they are given either OTM or
transdermal but the risk of abuse by humans is high.
Tramadol
Weak mu receptor agonist. Can be used in dogs and cats but has a very bitter taste and is often refused by many felines. Decent for
acute and chronic pain management and it may have increased benefit if given chronically because it inhibits the reuptake of
norepinephrine and serotonin. It should not be used in conjunction with other drugs of this nature or TCA’s or MAOI’s. Tramadol
may increase the seizure threshold so use caution in animals with a seizure history.
Gabapentin
Antiepileptic at high doses and anti-hyperalgesic at moderate doses. Works well for the treatment of neuropathic pain. Drug should be
stepped down when discontinued to avoid rebound pain. Liquid form may contain xylitol so it is not recommended for use in dogs and
cats. It is not an analgesic in and of itself so it should be used with other drugs like NSAIDS or tramadol. Excreted unchanged in the
urine so care should be taken when dosing renal patients.
Amantadine
NMDA antagonist and is a great analgesic adjunct for acute and chronic pain in dogs and cats. It blocks wind up or central
sensitization in the dorsal horn of the spinal cord. It is used as an antiviral drug in humans and can be used in combination with
NSAIDS or tramadol. Available in capsule and liquid. Excreted unchanged in urine so use caution in renal patients.
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Fentanyl patch
Class II controlled substances. Transdermal patch will provide systemic absorption and provide 3-4 days of analgesia. If removed
prior to 3 days it will continue to provide analgesia for 6-12 hours after patch removal.
Patch is very popular because it is easy to use but the absorption rate in dogs and cats can be highly variable. It may work really
well for some patients and not at all in others. It takes about 6-12 hours in cats and 12-24 hours in dogs to reach blood levels so
opioids should be supplemented until the patch kicks in. 12.5 mcg/hr; 25 mcg/hr; 50 mcg/hr; 100 mcg/hr. patch size is selected based
on patient weight. The patch can be placed anywhere on the body where there is intact hairless skin.
Transdermal fentanyl or recucyra
Recently approved for use in the US. It is a transdermal fentanyl solution (50 mg/ml) that is applied to the skin between the shoulder
blades 2-4 hours pre-operatively and will provide up to 4 days of analgesia. It is not meant to replace the use of other opioids during
surgery but may prove to be enough analgesia when used in conjunction with other CRI’s like lidocaine, locals or NSAIDS to provide
multimodal analgesia. Proper training is necessary prior to use and extreme care must be taken to prevent direct contact with the site
of application for at least 3 days.
OTM buprenorphine
A common post-op drug used in cats. Buprenorphine is a partial mu agonist and a class II controlled substance. Transmucosal
administration in the cat has almost 100% bioavailability. OTM means allowing the drug to be aborbed across the mucous
membranes, not given orally. Oral administration is not efficacious due to the first pass effect. The bioavailability of OTM
buprenorphine in dogs is around 30% so this route is not recommended in dogs.
SR buprenorphine
A compounded medication that is not FDA approved. The drug is set in a lipid carrier which allows it to absorb over a period of time.
It is given SQ and may sting on administration but can provide up to 72 hours of analgesia. This drug is used more frequently in cats
than dogs likely because they seem to tolerate it better. High doses can cause euphoria (purring, rolling, rubbing). This drug is very
difficult to reverse and may require hospitalization for supportive care and a naloxone CRI in extreme cases.
Simbadol
A high potency buprenorphine for SQ use in cats. It provides 24 hours of analgesia and is well tolerated by most felines. Side effects
are similar to SR buprenorphine but Simbadol is FDA approved and well regulated.
Rough recoveries
The majority of patients who have been given a balance of anesthetic drugs will have a smooth recovery. However, some will wake up
dysphoric or painful despite our best efforts. The quality of the induction, the temperament of the patient, previous rough anesthetic
recoveries and the length of the procedure can all affect the recovery. Evaluate analgesic history and effectiveness throughout the
procedure and especially prior to recovery. If the duration of action of a sedative/analgesic has lapsed, consider re-dosing prior to
recovery or at least be ready with analgesics.
Rough recoveries can be due to pain, dysphoria or emergence delirium and it is often difficult to determine which is which.
•
Dysphoria: characterized by agitation, excitement, restlessness, excessive vocalization and disorientation. Patient is not
responsive to human voice and will not look/focus on you. Cats tend to act as though they are hallucinating, they may openmouth breathe, vocalize and pace. Dysphoria is often precipitated by opioids and patients that are dysphoric from opioids will
not benefit from additional opioids. They may however, benefit from a low dose of butorphanol or naloxone to reverse the
side effects of opioids. This may then lead to a painful patient because reversal removes or lessens analgesia in an attempt to
calm the patient so adjunctive analgesics may be necessary to keep them comfortable.
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Emergence delirium: dissociated state of consciousness in which the patient is unaware of their surroundings. Patient may be
excited, agitated, restless and they may vocalize. This most often occurs in patients who have no sedative drugs on board or
when recovering from a dissociative anesthetic (ketamine, telazol). Other situations explained in the human literature that may
preclude emergence delirium include hypoglycemia, hypoxia, severe hypercapnia, hypotension and distended bladder.
•
There are a few ways to handle this situation;
o Restrain the patient until they have exited this post-anesthesia excitement phase. This is not always possible or safe.
o Reanesthetize the patient using induction drugs, reintubate or supplement oxygen and allow the patient to wake
back up (this is called a do-over)
o Reanesthetize and also give a sedative like dexmedetomidine or acepromazine
o Just give a sedative and hope it works before someone gets hurt!
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Pain: When dealing with rough recoveries it is important to address potential pain as well as anxiety since our patients cannot
verbalize when they hurt. Painful patients are responsive to human voice and will relax and stop vocalizing once analgeiscs
take effect. Dexmedetomidine is an excellent choice in patients that can handle the drug because it offers both analgesia and
sedation and is fully reversible. It is possible to achieve the desired effect with very small doses given IV (1-2 mcg/kg).
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•
•
Slow recoveries: Some patients seem to take forever to wake up. Hypothermia can slow down drug metabolism and lead to a
prolonged recovery. Keep patients warm as they recover and help circulation by gently massaging and moving the limbs.
Post-operative opioids can also re-sedate a patient after surgery. These drugs are given to control pain so it is not
recommended that they be reversed unless necessary. If necessary, reversal can be achieved with butorphanol or low dose and
titrated naloxone to reverse the side effects but preserve most of the analgesia.
Rapid recoveries: Rapid recoveries can be dangerous if the patient is dysphoric or delirious. Many rapid recoveries are due
to patients waking up on inhalant alone- no real analgesia and very little premedications still on board. These recoveries can
not always be predicted but by staying ahead of pain management and conscious of when premeds wear off, many rapid and
rough recoveries can be avoided.
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The Cool Observer:
Monitoring Anesthesia with Confidence
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
Our goal as anesthetists is to provide our patients with an expert balance between the effects of anesthetic drugs, both wanted and
unwanted, the affects of underlying illness and the intensity of procedural stimulation. To achieve this, we must depress the central
nervous system sufficiently to keep our patients unaware and relaxed, immobile and pain-free while at the same time maintaining near
normal cardiopulmonary function. This compromise to homeostasis brings with it the potential for problems. However, the source for
most anesthetic complications is human error (70%) and those errors are often associated with poor patient monitoring. Constant
vigilance of the anesthetized patient allows us to be proactive rather than reactive through anesthetic depth adjustment and need-based
patient support. As anesthetic drugs have become more refined and physiologic monitors more sophisticated, successful anesthesia is
no longer defined as the lack of mortality- just surviving anesthesia isn’t enough- but by the lack of morbidity. Our ultimate goal is to
bring patients through the anesthesia experience without any ill effects.
The American College of Veterinary Anesthesia and Analgesia or ACVAA published a position statement in 2009 regarding
recommendations for monitoring anesthetized veterinary patients. The ACVAA recommends frequent and continuous monitoring of
circulation, oxygenation, ventilation and body temperature by trained personnel. Appropriate physiologic support through the
utilization of hands-on monitoring in conjunction with physiologic monitors can improve the practice of veterinary anesthesia.
However, anesthetic monitors are only as good as the person using them- it takes a well-trained technician or nurse to be able to
recognize abnormalities and know how to properly respond.
Circulation
Adequate blood pressure is necessary to deliver oxygen and nutrients to all tissues in the body. The components of blood pressure
include systolic (peak pressure during contraction; stroke volume and arterial compliance), diastolic (minimum pressure during
relaxation of the heart; systemic vascular resistance and heart rate) and mean arterial pressure (driving pressure for organ perfusion).
Normal values: Systolic 100-140 mm Hg, Diastolic 50-100 mm Hg, Mean 70-120 mm Hg
Arterial blood pressure is comprised of cardiac output (the volume of blood ejected over one minute) and systemic vascular
resistance (the resistance offered by the peripheral vessels). Stroke volume (the volume of blood pumped with each beat) and heart
rate make up cardiac output. Preload (the volume of blood returned to the heart), cardiac contractility (the intrinsic strength of the
heart’s contraction) and afterload (the tension against which the ventricle must contract) all contribute to stroke volume. Afterload is
also a factor in systemic vascular resistance as is vessel diameter.
Autoregulation is the body’s ability to maintain normal perfusion to vital organs despite changed in systemic arterial pressure.
Autoregulation can maintain normal renal blood flow when systemic blood flow falls outside of 60-160 mm Hg range.
There are two ways to measure blood pressure, indirectly using non-invasive methods and directly using invasive methods. Noninvasive methods include the use of oscillometric blood pressure monitors and a Doppler; both utilize a pneumatic cuff placed over a
peripheral artery. The width of the blood pressure cuff bladder should be 40% of the circumference of the limb to obtain an accurate
reading. Cuffs that are too large may lead to underestimated pressures and cuffs that are too small may lead to overestimated
pressures. It is better to choose a wider cuff over a smaller one if the ideal size is not available as the margin of error is less. The
monitor should be set to read every 3-5 minutes for anesthetized patients. Blood pressures read more frequently do not given the limb
a chance to recover and re-perfuse with blood; pressures read less frequently may lead to missed events.
The Doppler can be a more accurate way of monitoring blood pressure in small patients but is prone to user error. Cuff selection
and placement, maximum inflation pressure, and deflation rate are determined by the operator and can vary greatly. In dogs, the
pressure at which the sound of blood flow returns after cuff inflation reflects the systolic blood pressure. In cats the pressure more
closely reflects the mean arterial pressure.
Invasive blood pressure (IBP) measurement is the gold standard of blood pressure monitoring. This method requires the aseptic
insertion of a catheter into an artery (dorsal pedal, coccygeal, femoral, lingual, facial, auricular). Most monitors capable of measuring
invasive pressures will display a continuous systolic, diastolic and mean arterial blood pressure reading as well as a waveform. By
observing the velocity or upswing of the arterial pressure wave (anacrotic ascending limb) one can glean information about changes in
cardiac contractility. This method of blood pressure assessment is essential in a number of clinical settings including major surgery,
trauma and critical care.
Since oscillometric monitors estimate blood pressure and are great trend monitors, isolated abnormal readings may not be a cause
for alarm. If the blood pressure is trending, evaluate the patient by assessing anesthetic depth and vital signs. Adjustments should be
made based on findings (deepen anesthesia, assist respirations, provide more analgesia etc). If the blood pressure is trending down the
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same algorithm is used but the corrective steps will differ. If sudden and significant changes in blood pressure occur, evaluate the
patient and communicate with the clinician then recheck the pressure and make adjustments based on findings.
Hypotension is defined as a systolic blood pressure less than 80 mmHg and a MAP of less than 60 mmHg in small animals. The
reduction may be significant enough to cause serious complications including shock and death. Consequences of hypotension may
include hypoxemia, reduced drug metabolism, worsening of V/Q mismatch (see Reasons for Hypoxemia), delayed anesthetic
recovery, renal failure, central nervous system (CNS) abnormalities (blindness, neurologic deficits), shock, cardiac arrest and death.
•
Drug side effects/excessive anesthetic depth: Inhalants, acepromazine, anaphylaxis or histamine release (rapid IV
morphine), radiographinc contrast media, beta blockers, rapid IV antibiotics etc.
•
Decreased venous return to the heart: Hemorrhage, fluid loss, compression of vena cava, increased intra-abdominal
pressure, mechanical or manual ventilation
•
Cardiac disease: Arrhythmias, valvular disease, cardiomyopathy, congestive heart disease, pericardial effusion
•
Mechanical: Closed pop-off valve, overinflated re-breathing bag (decreases venous return)
•
Shock/vasoactive substance release as seen with manipulation of damaged or diseased organs
Hypertension is less common in veterinary anesthesia but no less important. Hypertension can cause greater swings in blood
pressure and end-organ damage and may be the result of:
•
Mechanical error
•
Sympathetic stimulation: Hypercarbia (indirect SNS stimulation), pain, light level of anesthesia
•
Anesthetic drugs: Alpha-2 agonists, ketamine, inotropes, pressors
•
Disease states: Pheochromocytoma, chronic renal disease, hyperthyroidism, increased intracranial pressure, heart
disease, etc.
Treatment options for hypo- and hypertension depend on the underlying cause and may include an assessment and adjustment of
anesthetic depth, assessment of analgesic efficacy, expansion of intravascular volume (hypotension) and possibly drug therapy.
The ECG peripherally detects the electrical signals generated by the heart. This monitor reveals information about the heart’s
electrical activity but not it’s mechanical function. The ECG is essential in diagnosing arrhythmias and should be used during the preoperative evaluation of high-risk or trauma patients, intra-operatively for all procedures, and post-operative for those cases requiring
follow up information on the electrical stability of the heart.
Conduction
The P wave, the first small and usually positive wave signifies atrial depolarization initiated by the SA node. There is a brief pause
between the P wave and the QRS complex which corresponds to the time it takes for the impulse to travel from the SA node through
the AV node and bundle of His. This pause is called the P-R interval and it also represents the time between atrial depolarization and
ventricular depolarization. The QRS complex represents ventricular depolarization. This complex starts out with a negative deflection
(Q) and then takes a sharp and significant upswing (R) and then comes back down sometimes dipping just below baseline (S).
Depolarization should happen quickly producing a narrow QRS complex. A short pause is seen after this QRS complex followed by
the T wave, this is called the ST segment. The T wave represents ventricular repolarization. The time between the R wave of one
complex and the R wave of the following complex is termed the R-R interval. This interval helps us determine heart rate and
regularity. A normal sinus rhythm follows the conduction pattern from its origination in the SA node, through the AV node, Bundle of
His, bundle branches and Purkinje fibers. Since the SA node has the fastest impulse rate it typically overrides the other pacemaker
cells in the heart.
In the anesthetized patient, the ECG is used as a means of detecting dysrhythmias and not necessarily for diagnosing arrhythmias.
ECG’s are a great way to monitor heart rate and rhythm but the ECG can appear normal when myocardial performance and blood
pressure are poor.
Common arrhythmias
•
1st degree AV block: prolongation of the PR interval
•
2nd degree AV block: dropped QRS complexes
o Type 1: variable PR interval (av node fatigue)
o Type 2: constant PR interval before and after dropped beat (more serious- can progress)
•
3rd degree AV block: complete dissociation between SA and AV node
•
VPC’s: Impulse originating distal to SA node which can effect hemodynamics
•
V-tach: rapid ventricular rate, unstable rhythm
•
V-fib: Irregular tachyarrhythmia, unstable, arrest
Oxygenation
Oxygenation is the process of taking oxygen molecules from inspired air and delivering them to tissues to sustain aerobic cellular
metabolism. PaO2 is the measure of oxygen dissolved in plasma and it is determined by arterial blood gas measurement. This value
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tells us the efficiency of the lungs to deliver oxygen to the blood and is measured in mmHg (millimeters of mercury). Normal PaO2
values depend on inspired O2 concentration. To determine the normal PaO2 values, multiply inspired oxygen concentration by 4-5.
For example, room air is ~ 21% O2 so the normal PaO2 value for an animal breathing room air is 80-110 mm Hg. A patient breathing
100% oxygen should then have a PaO2 value of 400-500 mm Hg. SpO2 is peripheral oxygen saturation of hemoglobin that is
measured as a percent and estimates PaO2. The numbers of concern for each value are not equal because they are based on the normal
oxyhemoglobin dissociation curve. This curve illustrates the relationship between PaO2 and SpO2.The pulse ox utilizes wavelengths
of light; deoxygenated blood absorbs red light whereas oxygenated blood absorbs infrared light. The ratio of red to infrared light
provides us with an SpO2 value. An SpO2 of 95% and above represents adequate oxygenation and a precipitous drop in PaO2 can be
seen at an SpO2 of 94% and below indicating early hypoxemia. When the SpO2 falls to 90% the PaO2 is as low as 60 mm Hg which is
defined as severe hypoxemia and warrants treatment. There are five reasons for hypoxemia:
Low inspired oxygen concentrations is usually not an issue when using 100% O2, but it is important to check the oxygen supply
and make sure the flowmeter is on and in good working order. If using N2O, check ratios or discontinue mixture. A sedated or
anesthetized animal breathing room air is often at risk for hypoxemia making supplemental oxygen
Hypoventilation is common under anesthesia in spontaneously breathing patients because most anesthetics are respiratory
depressants. An animal that appears to be breathing adequately may not be. The adequacy of ventilation can only be determined by an
arterial blood gas or estimated using end-tidal CO2 monitoring. Patients at risk for hypoventilation (obese, geriatric, dorsal
recumbancy, deep anesthesia) should be manually or mechanically ventilated.
V/Q mismatch stands for ventilation (V) and perfusion (Q) mismatch. It is characterized by inflated alveoli that are not perfused
(ventilation is good but blood flow is bad) or perfused alveoli that are not well inflated (blood flow is good but ventilation is bad).
Some common causes of V/Q mismatch include anesthesia, inadequate ventilation, atelectasis, hypotension, positioning.
Diffusion impairment is an increase in the distance that oxygen has to travel to get from the alveoli to the capillary and viceversa. Pulmonary edema, pulmonary fibrosis and pneumonia can all cause diffusion impairment.
Shunting is defined as venous blood by-passing oxygenation in the lungs and mixing with arterial blood decreasing PaO2.
Collapsed lung lobes, PDA and VSD can all lead to shunting and hypoxemia.
Many pulse-oximeters are prone to malfunction, bias and variation especially if they have been designed to be used on humans
instead of animals. Some potential reasons for flawed readings include the fact that tissue, venous/capillary blood, and skin pigment
all absorb infrared light and motion, location of the probe, wetness/dryness, tissue thickness, electrical/optical interference can effect
readings. When inaccurate, the pulse-ox is usually inaccurately low. Check patient status first, then troubleshoot monitor because a
poorly functioning monitor may indicate poor systemic perfusion.
All monitors have limitation and the pulse-ox is no exception. This monitor does not assess the adequacy of ventilation; it only
estimates the amount of oxygen saturating the present hemoglobin. It also gives a pulse rate and in monitors with plethsysmography (a
graphic waveform of blood flow beneath the probe) you can glean some information concerning pulse pressure and volume status.
Also, it can be misleading in anemic patients who may have an SpO2 reading of 100% (available hemoglobin is saturated) when in
fact their tissues are hypoxic. This monitor can give the anesthetist a false sense of security because animals on 100% oxygen won’t
indicate impending hypoxemia until the PaO2 falls to 80 mm Hg (all the way from 400!).
Ventilation
The capnometer gives us end-tidal carbon dioxide (EtCO2) value which estimates PaCO2. PaCO2 is the amount of CO2 dissolved in
arterial blood and it gives us information about how well an animal is ventilating. Carbon dioxide is important in two ways, it defines
the respiratory cycle and it is a by-product of cellular metabolism (cells produce it, lungs excrete it). As an anesthetic monitor, the
capnometer non-invasively gauges the adequacy of ventilation and it helps guide assisted breaths and mechanical ventilation. This
monitor increases our ability to detect potential problems by alerting us to leaks within the breathing system, apnea and fluctuations in
respiration on a breath-by-breath basis, deviations in chest compliance and changes in cardiac output (including the effectiveness of
chest compressions during CPR). It can also help us determine if a patient is properly intubated and alerts us when a patient is
inadvertently extubated.
Normal PaO2 is 35-45 mm Hg and the end-tidal CO2 level is typically 3-5 mm Hg greater than the actual PaO2. For this reason, the
appropriate normal range for EtCO2 is 30-45 mm Hg. Abnormal EtCO2 readings may have a respiratory or a metabolic cause.
•
Elevated EtCO2 (> 45 mm Hg)
o Hypoventilation, excessive depth, inappropriate ventilator settings, exhausted soda lime, machine
malfunction, hyperthermia, airway obstruction, abdominal or thoracic restrictive disease, pleural space filling
•
Low EtCO2 (< 30 mm Hg)
o Hyperventilation, light level of anesthesia, hypoxemia, pain, hypothermia, inappropriate ventilator settings,
decreased cardiac output
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Normal levels of inspired CO2 range from 0-3 mm Hg and any value greater than 3 mm Hg may indicate a problem. Common
causes of elevated inspired CO2 levels include a leak in the breathing system or machine, excessive dead space, exhausted soda lime
or inadequate fresh gas flows in a non-rebreathing system
Temperature
Temperature can be monitored intermittently via rectal thermometer or continuously via rectal/esophageal probe connected to a
mechanical monitor. Properly placing a reusable probe down the esophagus provides an easy and accurate core body temperature
reading. Minimizing patient heat loss can be achieved by controlling conductive, convective, radiant and evaporative heat loss and by
providing supplemental heat support. Insulating a patient from the cool environment with the use of blankets and towels and
minimizing prep times can help maintain normal body temperature. Convective warming devices can also be employed and are an
efficient way to maintain and improve body temperature under anesthesia. Rice socks, electric heating blankets and warm water
bags/bottles/gloves should be avoided because they have the tendency to cause burns (Haskins, 1999). If they must be used, do not
allow the heat source to contact the patient directly and remove once they cool to patient temperature as they will begin to absorb heat
from the patient at that time.
Consequences of hypothermia
•
The release of catecholamines in response to the stress of a decreased body temperature
o Subsequent vasoconstriction, tachycardia and hypertension increase post-operative morbidity
•
Coagulation deficiencies
o Hypothermia impairs platelet function, decreases coagulation pathways and increases fibrolysis
•
Decreased wound healing
o Thermoregulatory vasoconstriction reduces wound oxygen tension, impairs oxidative killing by neutrophils
and reduces collagen deposition
o Hypothermia directly impairs immune function and increases post-operative wound infections (Sessler, 2006)
•
Reduction in necessary amount of inhalant
o Hypothermia increases solubility and decreases clearance leading to the significant potential for anesthetic
overdose
•
Hypothermia leads to post-operative shivering
o Shivering greatly increases metabolic oxygen consumption and when coupled with residual respiratory
depression and atelectesis, hypoxemia is likely.
The intelligent use of mechanical monitors will aid the clinician in supporting patients during times of compromised homeostasis as
seen under anesthesia. Respecting the guidelines put forth by the ACVA to continuously monitor circulation, oxygenation, ventilation
and body temperature will improve the practice of anesthesia and reduce patient morbidity by providing positive anesthetic outcomes.
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The Ins and Outs of the Anesthesia Machine
Kristen Cooley, BA, CVT, VTS (Anesthesia)
University of Wisconsin
Madison, WI
The anesthesia machine
The components of the anesthesia machine work together to deliver controlled amounts of oxygen and anesthetic gas to a breathing
system. Anesthesia machines are designed to deliver volatile anesthetics in the presence of oxygen. One hundred percent oxygen is
commonly used to deliver anesthetics for the delivery of adequate amounts of O2 to tissues. Oxygen delivery is reduced because
anesthetics reduce tidal volume and cause some degree of respiratory depression.
Oxygen cylinders
Oxygen is often obtained as compressed gas in a pressurized cylinder. Pressurization is necessary to fit a large amount into a relatively
small container. Various sized tanks are available and each size is designated with a letter A-H but the most commonly used sizes are
E cylinders and H tanks.
When the cylinders are full they contain 2200 psi of gas with varying volumes based on size:
E-cylinders
•
Small and easy to carry
•
Holds ~770 L of oxygen
•
Commonly found attached to an anesthetic machine
H-cylinders
•
Huge and heavy
•
Holds ~7000 L of oxygen
•
Commonly found in a closet or chained to a wall
Other medical gases can be obtained in compressed cylinders as well. To keep all medical gases organized they are each assigned a
cylinder color.
•
Oxygen is green in the US, white in Canada and Europe
•
Nitrous oxide is blue
•
Air is yellow in the US, grey, white and black in Canada and Europe
•
Nitrogen is black
All knobs, hoses and connectors associated with these gases should also be of the designated color.
Pressure gauge and regulator
Located on the cylinder yoke, this apparatus provides a safe, constant operating pressure within the machine regardless of the pressure
in the tank. It also has a gauge connected to it that displays the tank pressure. The volume of gases that are not liquid at room
temperature can be determined based on the tank pressure. The volume of gas is proportional to the pressure in the tank. For example,
if a full tank is 2200 psi and contains 600 liters of gas then a half full tank will have a pressure of 1100 psi when it contains 300 liters
of gas.
Flowmeter
The flowmeter is made up of a graduated glass tube and some sort of float (ball or plumb bob). It is typically expressed in L/min or
mL/min. Oxygen enters the bottom of the flowmeter and exits the top. It allows the anesthetist to adjust the O2 flow rate. The flow of
oxygen can be increased to speed the change of inhalant concentration in the machine.
Time constants (TC)
A time constant represents the volume of the machine in relation to the flow of gases. It takes approximately 3 time constants to see a
95% change in the concentration within the system when a change is made to the vaporizer. A typical small animal anesthesia
machine volume (components of breathing system) will have around a 5 L volume and is dependent on the size of the absorbent
canister, breathing bag size and diameter and length of the breathing hoses. Math
•
3 TC X 5 L / 1L/min = 15 min
With a flowrate of 1 L/min it takes 15 min to approach a steady state
•
3 TC X 5L / 2L/min = 7.5 min
With a flowrate of 2 L/min it takes 7.5 min to approach a steady state
Factors affecting changes in anesthetic concentration include hypoventilation and apnea. By assisting ventilation you facilitate gas
exchange, this includes oxygen as well as anesthetic
CAUTION! Increases in flowrates should always be monitored closely because an increase in system flow also means an increase
in flow to patient. Gases are dry and cool and can be very drying to respiratory tract and will cool patients very quickly. Never close
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the pop-off valve when you have higher flows because pressure builds much quicker so you have less time to react! High flows waste
anesthetic gas and oxygen and money!
Vaporizers
Vaporizers are responsible for converting liquid anesthetic to a gas. It adds controlled amounts of anesthetic gas to O2 and it can only
release anesthetic in the presence of oxygen (or N2O). Each vaporizer is calibrated for a specific agent based on that agent’s vapor
pressure. It is essential to never fill a vaporizer with an anesthetic other than the one it is intended for.
Oxygen flush valve
This button allows fresh oxygen to by-pass vaporizer and enter breathing circuit directly at 30-50 L/min. It is a handy but dangerous
component because over pressurization is easy.
Flush valve CAUTION
•
Use with extreme care or not at all when the circuit is connected to a patient
•
NEVER use with a non-rebreathing system
•
NEVER use when pop-off is closed
•
DO NOT use in small patients
•
The use of this valve decreases anesthetic concentration in the system
Fresh gas outlet and common gas inlet
The gas mixture (O2 and anesthetic) exits the vaporizer and machine at the fresh gas outlet. The mixture follows a flexible tube and
enters the breathing system at the fresh gas inlet. This port is necessary to hook up a non-rebreathing circuit
Flutter valves
Fresh gas enters the one-way inspiratory valve on its way to the patient and then is exhaled through the one-way expiratory valve.
These valves are only utilized with a circle system to allow for re-breathing of gases.
Pop-off valve/APL
The pop-off or adjustable pressure limiting valve prevents build-up of pressure or volume within the circuit. Most will vent pressure at
2 cm of water. Allowing pressure to build-up may impede venous return or cause barotrauma. It is good practice to always keep a
hand on the pop-off valve (when you close it) to make sure that it gets re-opened. There are pop-off occlusion valves are available
(SurgiVet.com).
Carbon dioxide absorber
The carbon dioxide absorber contains absorbent granules that remove CO2 from expired gas. Any gas that gets returned to the patient
passes through the carbon dioxide absorber on its way back. Utilization of the carbon dioxide absorber lowers fresh gas flows, reduces
waste of anesthetic and oxygen, lowers the overall cost of anesthesia by allowing for the re-breathing of gases.
Carbon dioxide absorbent is made up of granules of calcium hydroxide or barium hydroxide. When they come into contact with
CO2 an exothermic reaction takes place that produces both heat and water. The granules must be changed when exhausted. Many
formulations have a pH color indicator to alert when to change it. Granules start off white and may change to lavender or blue when
they have had their fill of carbon dioxide. This is a short-lived chemical reaction allowing spent granules to revert back to white once
they are no longer being bombarded with CO2. There are formulations available that elicit a permanent color change. If the status of
the granules is in question, handle them; fresh granules can be easily chipped and crumbled whereas spent granules are very hard and
brittle.
Manometer
The manometer measures the pressure of gases within the anesthetic circuit and patient. This gauge is very useful when breathing for a
patient or setting up a ventilator and should be referenced with each manual breath.
Scavenging system
The scavenging system collects waste gas and disposes of it. Two types of scavenging systems exist, passive disposal made up of noncirculating ventilation systems or activated charcoal and active systems consisting of a central vacuum.
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Components of breathing system
The breathing system is comprised of everything after the common gas outlet that breath passes through. This includes the breathing
hoses, breathing bag, CO2 absorber, and scavenge system. The breathing system functions to deliver oxygen and anesthetic gas to the
patient, to remove CO2 from exhalation and to facilitate manual ventilation.
Anesthetic systems/circuits
The two types of anesthetic circuits available include circle or rebreathing systems and the non-rebreathing circuit. The circle system
is commonly reserved for patients greater than 7 kg and it utilizes the inspiratory and expiratory valves as well as the CO2 absorber.
The non-rebreathing system is most often used for patients less than 7 kg and bypasses the bulk of the anesthesia machine utilizing
only the flowmeter and vaporizer.
Circle systems
‘Y’ hoses: Two legs connected by a “Y” at the patient end
•
Universal F: One coaxial tube that connects to inspiratory/expiratory valves using a small hose
Non-rebreathing systems
•
No exhaled gas is returned to patient
o Adequate oxygen flows required to prevent rebreathing of gases
o 250-500 ml/kg/min
•
Evacuated by scavenge based on O2 flows
•
No CO2 absorber
•
Many types, two common are both modified Mapleson D
o Ayers T
o Bain
Circle system vs. Non-rebreathing system
•
Circle system
o Low flows
o Rebreating of gases
o More economical
o Recycled air is warmer and humidified than fresh gas
o May be cumbersome
o More resistance to breathing for small patients
•
Non-rebreathing system
o Little resistance to breathing
o Does not require a CO2 absorber
o Allows inspired concentrations of anesthetic to be changed rapidly
o Promotes hypothermia and drying of respiratory tract
o Can be wasteful if used in larger patients (high flows)
Breathing bags
Breathing bags (also called rebreating bags or reservoir bags) should hold a minimum of 60 ml/kg of the patient’s body weight. This
can also be figured out by multiplying 5-6 X tidal volume (10-15 mL/kg). When choosing a bag size it is important to always round
up. An appropriately sized bag allows patient to take a large breath, it allows the anesthetist to observe breathing and to breathe for the
patient. The size of the bag does matter, if the bag is too big it impairs monitoring of breathing rate, adds volume to machine and
slows changes in inspiratory anesthetic concentrations when settings are altered. If the bag is too small the animal is unable to take an
adequate breath because the bag collapses on inspiration.
Endotracheal tubes
Many endotracheal tubes are intended for one time use only. The biggest drawback of reusing them is that the cuffs tend to wear out
over time. All ET tubes should be checked for leaks prior to each use. To do this, make sure the cuff inflates and stays inflated. You
can also place an inflated tube in a bowl of water and look for leaks/bubbles. All leaky tubes should be discarded.
Mechanical dead space
Mechanical dead space is the area where bi-directional flow takes place. This includes the endotracheal tube and anything between the
Y-piece and the ET tube such as the CO2 monitor adapter, swivel adapter, elbow etc. Excessive pieces should be kept to a minimum in
small patients. It is important to note that hose length does not contribute to dead space but can increase the resistance to breathing.
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Splinting Basics for Orthopedic Patients
David Dycus, DVM, MS, DACVS, CCRP
Veterinary Orthopedic and Sports Medicine Group
Annapolis Junction, MD
Bandages, splints, and slings are useful for managing orthopedic patients and are all considered as external coaptation devices. Until
recently very little advances were made in the field of external coaptation. With increasing expectation by owners this field has
evolved together with human orthotists and prosthetists to include orthotic devices and prosthetic limbs. It is useful for the
management of wounds, edema reduction, and fracture management by providing stability and support for soft and osseous tissues.
The central theme for any patient with external coaptation is comfort and function. With appropriate fit and construction patient
comfort and tolerance is improved. External coaptation for fracture management can be used as the primary fixation, temporary
fixation, and ancillary fixation. For primary fixation the bandage and splint will be the sole means of fixation where as with temporary
fixation the bandage/splint may be used to cover open fractures or stabilize a fracture until definitive surgical correction. Ancillary
fixation with external coaptation is useful for additional support such as after bone plating to prevent implant breakdown as seen with
distal radius and ulna fractures.
The Robert Jones Bandage (RJB) and the modified Robert Jones Bandage (mRJB) are the most commonly utilized bandages in
orthopedic external coaptation. Uses of these bandages are limited to injuries distal to the elbow or stifle. Injuries such as wounds,
fractures, dislocations/luxations, and strains can be managed by RJB or mRJB as either a primary, temporary, or ancillary means.
There is variation in usage of these bandages ranging from wound dressings, padding, and rigidity. The amount and type of padding
and/or reinforcement materials are determined by the type and location of the injury and the compression and support needed.
The RJB is a bulky bandage indicated for helping stabilize fractures, dislocations, or post-operative edema following surgery for
injuries distal to the elbow or stifle. When applied appropriately the RJB provides support and immobilization, reduces and prevents
edema, and limits effusion. The bulk of the bandage when evenly applied achieves compression without the compromise of the
vascularity of the soft tissues. It is typically well tolerated by patients, but its bulk may make ambulation difficult. The RJB is very
effective for temporary stability and immobilization; however, the bandage is unsuitable for primary fracture fixation, as the thick
cotton padding will tend to loosen and contribute to instability at the fracture site.
Materials required for a RJB include 1 inch white adhesive tape, 1-3 rolls of 1 pound 12 inch cotton, 1-3 rolls of 3-4 inch roll
gauze, 1-2 rolls of 3-4 inch stretch tape (Vetwrap) and any wound dressings that may be needed. Before placing the bandage all
wounds should be treated and covered with the appropriate dressing. I will typically place strips of adhesive tape to form stirrups to
either the medial and lateral or dorsal and palmar/plantar aspects of the limb. The stirrups are then extended 3-6 inches past the digits
(and in many cases I will used a tongue depressor to attach the distal ends to). These stirrups will help prevent slippage.
Circumferential bands of tape should not be applied as this may obstruct the vascular supply. Next, apply the cotton beginning at the
level of the second and fifth digits while leaving the toenails of digits three and four exposed. The cotton should be applied tightly
(pulling too tight will simply cause the cotton to tear) with no wrinkles or twits. Apply the cotton from distal to proximal while
overlapping the pervious layer by 50% with each successive layer. Continue this cotton layers to mid-humerus or mid-femur, and then
return distally. The goal is to repeat until there is sufficient bulk achieved: 4-8 cm thick.
Following the cotton layer the rolled gauze is applied in the same manner as the cotton. To achieve a smooth bandage with uniform
tension 2-3 layers of gauze should be applied with even pressure so that the cotton is compressed by 40-50% (or it has a “ripe
watermelon” sound when tapping it with a finger). The tape stirrups are then separated, inverted, and applied to the gauze layer. The
outer (tertiary) layer is applied in the same manner as the previous two layers. This layer should be applied with caution as not to
apply too much tension causing over compression and vascular compromise. When completed RJB should be smooth in appearance
and should reveal the distal aspect of the toes and toenails of digits 3 and 4. Loosening of the cotton layer will occur within several
hours so bandage evaluation should be performed every 4-6 hours and a bandage change is recommended every few days or sooner if
complications arise.
A mRJB is similar to the traditional RJB; however, less padding is used and typically cast padding is used in place of rolled cotton.
A mRJB is indicated for light compression and partial immobilization of the limb distal to the elbow or stifle. It is useful for reduction
and prevention of post-trauma or post-operative swelling, soft tissue protection and limb support following surgical fixation or
removal of orthopedic devices. The mRJB is contraindicated if severe inflammation is suspected, and it does not provide rigidity and
complete immobilization of the limb. Therefore mRJB are not appropriate for temporary support of fractures or dislocations. The
thickness of the padding for a mRJB is approximately ½ to 2 cm (as compared to 4-8 cm for the RJB).
I tend to think about RJB for quick stabilization of a fracture until surgery, while a mRJB is going to be used more common such
as after surgery, or when incorporated into a splint (reinforced RJB).
A reinforced RJB is a type of bandage that incorporates a rigid material to enhance immobilization and support of the limb and
joints. This type of bandage offers the stability of the RJB without the bulk. Given that it is reinforced this type of bandage may be
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used as primary fixation for stable fractures in young animals. Different reinforcing materials can be used such aluminum rods, a preformed metal or plastic splint, or in the authors preference moldable materials such as fiberglass or thermoplast. The reinforcing
material is placed after the cast padding and rolled gauze have been placed. Then another layer of rolled gauze is used to hold the
material in place followed by the outer layer.
Preformed splints are available for both the front and hind limbs, which are traditionally used for stabilization of fractures or
luxations. Unfortunately, while preformed splints are available in various sizes, rarely is exact fit achieved. The author prefers to make
custom splints from either fiberglass or thermoplast, as molded splints are more efficient stabilizers of bones and joints. Because they
are custom fitted fewer soft tissue complications are seen and patient tolerance is improved. Most splints are applied lateral or palmar
in the front limbs or lateral in the hind limbs. Spica splints are a type of splint used to immobilize the shoulder or hip joint. The
bandage is applied like a routine MRJ; however, the material is then taken and applied around the torso. The Spica splint should
extend over the scapula or hip to dorsal midline. Rarely are Spica splints used for primary management of humeral or femoral
fractures, but rather used more commonly for temporary splintage or stabilization following elbow or shoulder luxations.
A Schroeder-Thomas splint is a traction device that is made from a wire frame and soft bandage material. When applied the limb is
suspended within the frame and it is thought that the splint counteracts muscle forces and immobilizes joints. The splint does not
adequately immobilize the shoulder or hip and is contraindicated for humeral and femoral fractures. Given that the Schroeder-Thomas
splint has largely been replaced by splints and casts the author considers it contraindicated for any use.
Complications of splints and bandages can range from minor issues such as skin irritation and mild dermatitis to limb and life
threatening conditions. Just by placing a bandage or splint there is a 63% chance of morbidity associated with it. Severe complications
such as fracture disease or limb necrosis can occur. Attention needs to be given to each patient when utilizing bandages and splints. It
is important that the toes be evaluated at least twice daily for any evidence of swelling. The bandage must stay clean and dry and
should be protected when the patient is taken outside. If the bandage becomes wet it should be changed immediately, otherwise
bandages should be changed every 5-7 days. Given the potential for complications strict communication with owners is necessary.
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My Top Tips on Managing Cancer Patients
Sue Ettinger, DVM, DACVIM
Dr. Sue Cancer Vet PLLC
Tarrytown, NY
Cancer is not a death sentence in pets. Chemotherapy is well tolerated in the majority of dogs and cats undergoing treatment. With
treatment, many cancer patients are not only living longer, but living well.
Importance of oncology
The pet is a family member, and owners often want same standard of care for their dogs and cats as they do themselves. Sadly, cancer
is leading cause of death in pets. “Cancer” is a scary word that is often equated with death. There is often a visceral fear of cancer, and
people think cancer equals pain and suffering. Owners think cancer treatment will just make the patient sicker. With cancer, there is no
hope. I disagree. Cancer is not a death sentence. While we all want a cure for cancer, I encourage thinking about many cancers as
chronic conditions that may require chronic therapy, such as kidney or heart disease. As an oncologist, I recommend treatment when
the pet is likely to live longer with it than without. Thankfully, most cats feel good, if not great, during treatment. I believe it is
important to approach the topic of cancer with knowledge, compassion, and a positive attitude.
Chemotherapy
Conventional chemotherapy
Conventional chemotherapy is typically given at high dosages, known as maximum tolerated dose, or MTD. The goal is to kill the
rapidly dividing cancer cells. But some normal cells that also have high turnover often can be temporarily damaged by MTD chemo.
Most commonly, it is the GI tract cells and the neutrophils that are temporarily damaged. As a result there is a break period to allow
these cell populations to recover. MTD is typically given weekly to every 3 weeks.
Chemotherapy drugs attack rapidly dividing cells. The normal tissues that typically are most sensitive to chemotherapy are the
bone marrow, hair follicles (alopecia), and the gastrointestinal lining. This is often referred to as “BAG”.
Bone marrow suppression most commonly results in a neutropenia but cats seem to be more tolerant than dogs. Neutrophils and
platelets are at greatest risk due to the shorter circulating lifespan, and shorter bone marrow transit times. Neutropenia is the doselimiting toxicity in veterinary oncology.
When giving a potentially myelosuppressive drug like doxorubicin, carboplatin and Lomustine, I personally like to check the
expected nadir (low neutrophil count) to see if antibiotics and/or a dose reduction are needed. The nadir typically occurs 7 days after
chemo administration. Pay attention to the neutrophil count, not the total white blood cell count. For some chemotherapy drugs the
nadir is more variable such as carboplatin and Lomustine. For cats, the nadir is can occur 7 to 28 days after treatment. In dogs the
nadir for carboplatin in day 10-14. Chlorambucil tends to cause delayed neutropenias and thrombocytopenias after chronic use.
Alopecia (hair loss) is due to damaging the rapidly dividing hair follicle. In dogs, potentially affected breeds have continuously
growing coats and include Poodles, Scottish Terriers, and Westies. In cats, alopecia is rare, but shaved areas tend to grow back more
slowly (limb catheters, abdominal ultrasounds). Cats more commonly lose their whiskers. The good news is that hair and whiskers
will re-grow once the treatments have completed. Occasionally, hair will grow back a different texture or color. In cats it is typically
softer, aka the “chemo coat”. It is important to remember pets do not care about this cosmetic side effect, and it does not impact the
quality of life. However, pet owners like to be advised about the whiskers and coat so they are not surprised.
Gastrointestinal (GI) toxicity includes vomiting, diarrhea, decreased appetite, nausea. It typically 1 to 5 days after chemotherapy
and is self-limiting – lasting on average 2-3 days. These side effects are less common in feline chemotherapy patients than dogs. I
often will use Cerenia or mirtazapine as needed.
How toxic is chemotherapy?
The overall toxicity rate is very low in veterinary chemotherapy patients. In my experience, only 15-20% experience side effects, and
this is even less common in cats than dogs. The primary goal is to provide the best quality of life possible for as long as possible. As I
say, live longer, live well. Most side effects are mild and medically manageable.
If there are side effects, I also typically will add prophylactic medications to prevent side effects like nausea, vomiting or diarrhea
as indicated. I recommend Cerenia SQ with the following drugs: vincas, doxorubicin, mitoxantrone, carboplatin, and the MOPP
protocol. I always recommend oral Cerenia for 4 days after doxorubicin in dogs to prevent nausea and vomiting. If the GI side effects
are more severe in a patient, the drug type or dosage may be adjusted at subsequent treatments to minimize the chance of side effects
recurring.
When a chemotherapy drug is used that is known to have a high potential for bone marrow suppression, a complete blood count
(CBC) is often checked after the treatment to see if the WBC are low. Antibiotics may be prescribed as a preventive measure.
Subsequent doses of chemotherapy are adjusted based on the results of the CBC. Unlike dogs, I do not routinely use prophylactic
antibiotics or GI medications unless the cat had issues with a prior treatment.
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In my experience, there is less than a 5% chance that a patient will need hospitalization. If this does occur, these patients are
usually hospitalized for typically 24-48 hours with supportive care including IV fluids and antibiotics. In my experience most
chemotherapy patients can successfully receive that drug again with a dose reduction.
Metronomic chemotherapy
In contrast to MTD chemotherapy, metronomic chemotherapy is pulse or low-dose continuous chemotherapy. This is typically
administered daily or every other day. The target is endothelial cells in that line tumor blood vessel. The goal may be tumor is
stabilized, but this prevents further growth and spread. Common chemotherapy drugs include Palladia, cyclophosphamide, and
chlorambucil and also with NSAIDS. There is still much to be learned including best drugs, dose, schedule, tumor types, and toxicity.
This can be considered for some dogs and cats with advanced metastatic disease.
What to do at the nadir visit?
In addition to running a CBC, it is important to get a good history, TPR (that temperature is so important in chemotherapy patients),
and a complete physical examination. I am always interested in knowing how the patient handled chemo –did she eat well, any
vomiting/diarrhea, did the owner use any nausea or diarrheal medications? For the exam, did he lose weight, was she febrile? The
nadir CBC should not be a technician appointment to just pull the blood sample. The history and exam are very important.
Pay attention to the neutrophil count, not the total white blood cell count. The nadir typically occurs 7 days after chemo
administration, but can vary (see above). I recommend antibiotics if the neutrophil count is <1500. If the patient has <1500
neutrophils and is afebrile and feeling well, I recommend managing as an outpatient. However, if the patient has <1500 neutrophils
and is febrile and sick, I recommend admitting for supportive care. Remember a febrile neutropenic is an oncologic emergency.
Also, I prefer that we get blood samples from the jugular veins for patients getting IV chemotherapy (unless thrombocytopenic).
Save those peripheral veins for treatment please. Finally many times the oncologist has run a recent chemistry panel, so check with the
oncologist, and try not to repeat unneeded blood work to keep costs down.
In addition to the chemotherapy targeting rapidly dividing bone marrow stem cells, other mechanisms for neutropenia includes
bone marrow infiltration with neoplastic cells (leukemia, advanced stage lymphoma, multiple myeloma) and increased consumption
due to infection.
Neutrophil
Fever,systemic
Plan
count
signs
(per uL)
1500-2500
No
Monitor
+/- treatment delay 2
to 4 days
<1500
No
Oral antibiotics
treatment delay
Consider dose change
<1500
Yes
ATH for IVF & IV
antibiotics
treatment delay
Dose change
Sepsis
Sepsis in chemotherapy patients is typically due to patient’s own flora - Gram negative from GI bacteria: E. coli, Klebsiella,
Pseudomona; Gram positive from skin bacteria: Staphylococcus epidermitidis and aureus, Anaerobes from oral bacteria. Predisposing
factors include neutropenia (infection risk well correlated with degree and duration), cellular immune dysfunction, humoral immune
dysfunction, prolonged hospitalizations, indwelling catheters, and poor nutrition.
History and clinical signs are typically straightforward - cytotoxic chemotherapy was administered typically 5 to 7 days ago.
Remember, the febrile neutropenic patient is an oncologic emergency!!! In addition the patient may have an inability to mount an
inflammatory response, so the lack of fever, pyuria, or radiographic changes of pneumonia does not rule out sepsis. Signs of illness are
unrelated to absolute neutrophil count, but are related to an increased susceptibility to local and systemic infections when neutropenic.
Gastrointestinal, urogenital, and respiratory infections are most common. Shock is also possible
The sepsis work up includes: CBC, Chemistry panel, UA & UCS (if >50,000 platelets). If respiratory signs are
present, chest radiographs are recommended, and TTW should be considered. Blood cultures may be needed, but
uncommon in my experience. Culture any catheters suspected as the infection source.
Treatment for sepsis includes: IVF and broad-spectrum IV antibiotics. Neupogen is human recombinant G-CSF. The MOA is
stimulation of proliferation & maturation of neutrophil precursors, and monocyte precursors to a lesser extent. It also primes
neutrophil for cell killing & neutrophil migration. The benefit for the febrile & febrile neutropenic patient is contradictory, and in my
experience, Neupogen is rarely needed. The recommended dose is 5 ug/kg SQ SID until neutrophil >1000.
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When should I lower chemotherapy dose?
Dose Intensity is chemotherapy given at MTD & shortest possible interval. It is important to remember than small dose changes can
have significant impact on cancer control. Dose reductions as small as 20% can decrease drug efficacy up to 50%. Dose reductions
should not be considered lightly.
Vomiting and diarrhea
Acute vomiting is typically associated with cisplatin, doxorubicin (Adriamycin), dacarbazine (DTIC), cyclophosphamide,
actinomycin, 5-FU streptozoticin. This can typically be prevented with pre-treatment
Delayed vomiting is more common in our patients. This is due to direct damage to rapidly dividing GIT cells (crypt cells) or via
the centrally mediated CRTZ stimulated via gut vagal efferents. Delayed vomiting is most commonly 2 to 5 days post-chemo and seen
with doxorubicin and the vinca alkaloids. Clinical signs include vomiting, diarrhea, anorexia, lethargy, weakness, + dehydration.
For work up, I recommend CBC, chemistry panel, UA, +/- fecal floatations and cultures. If abdominal pain is present, consider
AXR or AUS to rule out foreign body, obstruction, and intussusception. For patients with GI neoplasia, it can be challenging to
differentiate chemotherapy side effects vs. disease, and a good history can be key.
For outpatient treatment, I recommend NPO, food & water trial, bland diet, anti-emetics, antibiotics with severe diarrhea and a
probiotic. Do not forget to discontinue oral chemotherapy or delay chemotherapy treatment. In addition, I recommend prophylactic
therapy with the next chemotherapy
For inpatient, I add injectable antiemetics, IV fluid therapy, and IV antibiotics. An important note, I strongly encourage owners to
NOT EUTHANIZE at this time. It is amazing with 1 to 2 days of good supportive care how quickly these patients improve. And with
prophylactic therapy and a dose reduction, these patients can tolerate the same chemotherapy drug.
Don’t treat cats like small dogs when it comes to chemotherapy
Some chemotherapy drugs are dosed differently in cats. In dogs, weight and body surface area are used to determine the carboplatin
dose. In cats there is now a more accurate method to dose carboplatin in cats based on glomerular filtration rate, which is determined
with an Iohexol clearance test.
Side effects in cats are also different. Cardiotoxicity is a well-described adverse effect in dogs treated with doxorubicin, but it has
not been reported in cats. Sterile hemorrhagic cystitis (SHC) is a relatively uncommon complication of cyclophosphamide in dogs and
ifosfamide therapy in dogs and cats. SHC is typically associated with long-term use, but possible after single dose, and can progress to
bladder fibrosis. The incidence with cyclophosphamide has been reported to be 9% in dogs (7-24%), 3% in cats, and 24% in humans.
Unlike dogs, concurrent administration of furosemide with cyclophosphamide is not recommended in cats. Mesna, which binds the
SHC-inducing acrolein, is recommended for cats and dogs when administering ifosfamide.
Don’t monitor the bump or lump. Do get an aspirate or biopsy. Why wait? Aspirate. 
Visual monitoring of skin and subcutaneous masses is not enough. Even the most experienced veterinarian or oncologist cannot look
at or palpate a mass and know whether it is malignant or not. Cancer is a cellular diagnosis! It is always recommended to evaluate
masses that are growing, changing in appearance, or irritating to the patient. But these guidelines are not enough.
“See Something Do Something. Why Wait? Aspirate. Dr. Sue Cancer Vet®” (SSDS) provides guidelines for evaluating
superficial masses in dogs and cats. These guidelines will increase client awareness and will promote early cancer detection,
diagnosis, and early surgical intervention. In veterinary medicine, most skin and subcutaneous tumors can be cured with surgery alone
if diagnosed early when tumors are small.
See Something: When a skin mass is the size of a pea (1 cm) and has been present for at least 1 month,
Do Something: Aspirate or biopsy, and treat appropriately!
Why diagnose early? Obtaining a definitive diagnosis with cytology or biopsy early and before excision will lead to improved
patient outcomes for superficial masses. When smaller, superficial tumors are detected early, surgery is likely curative – this is
especially true for benign lesions and tumors that are only locally invasive with a low probability of metastasis. If tumors are removed
with complete surgical margins, the prognosis is often good with no additional treatments needed.
•
Pet owners need to be aware of the “pea” size requirement to have masses evaluated.
•
Veterinarians must measure and document the size of the mass in order to compare growth.
•
If > 1 cm (or size of large pea) and present for a month, the mass should be aspirated or biopsied.
•
Knowing the tumor type prior to the FIRST surgery will increase success of a curative-intent surgery
See Something Do Something, Copyright 2012 © Dr. Sue Ettinger, All Rights Reserved
References
Chretin JD, et al, JVIM, 2007; 21(1):141-8.
Rau SE, et al, JVIM 2010; 24(6):1452-7.
Vaughan MA, et al, JVIM 2007; 1(6):1332-9
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High Risk Cases:
Anesthesia for Patients too Sick for Anesthesia
Ralph Harvey, DVM, MS, DACVAA
University of Tennessee
Knoxville, TN
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•
•
•
•
Supportive care is based on recognition of patients needs.
Focused monitoring and patient evaluation leads to individualized care.
o Appropriate patient evaluation provides for the recognition of anesthetic risks and anesthetic concerns for that
specific patient and procedure. “Problem-based” anesthetic management is the framework for individualized
patient care.
What “anesthetic concerns” have you identified for this patient? “100 things are missed due to not looking for every 1
thing missed due to not knowing”.
Preanesthetic physical examination and laboratory analyses - individualized
“minimum data base” based on risk
diagnostic imaging
o radiographs, contrast studies, CT, MRI,
o ultrasonography, scintigraphy, etc.
other directed testing
ASA physical status categories
•
.
American Society of Anesthesiologists (ASA)
•
.
ASA I - excellent anesthetic risk
•
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ASA II - good anesthetic risk
•
.
ASA III - fair anesthetic risk
•
.
ASA IV - poor anesthetic risk
•
.
ASA V - guarded anesthetic risk
o additional “Emergency” designation (x)-E
Ventilatory complications
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Airway obstruction
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Inadequate Delivery of Oxygen
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Hypoventilation
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Inadequate Ventilation, Apnea
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Hyperventilation: Tachypnea or panting
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Irregular patterns of ventilation
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All anesthetics are respiratory depressants!
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Anesthetic overdose: Relative or Absolute
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Direct depression of central respiratory centers
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Secondary to circulatory depression
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Specific drug actions
Hypoventilation requires patient support.
Endotracheal intubation, ventilatory support by IPPV manual or mechanical ventilation based on patient monitoring, evaluate and
address the underlying problem.
Hyperventilation and/or panting are less common, but may reflect hyperthermia, pain, or occur as a side-effect of specific drugs.
Control of body temperature, management of pain, and control of ventilation may be necessary.
Support for Circulatory compromise
Hypotension is a common problem due to hemorrhage and/or vasodilatation. Circulatory support is largely based on fluid therapy,
including crystalloids, and colloids. A variety of fluids are now available, with blood substitutes serving and important need. Vasoactive agents help support blood pressure, cardiac function, and tissue perfusion.
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Temperature support
Hypothermia is an almost universal problem in small animal anesthesia and many areas of critical care. Risks of thermal support have
been great with older heating strategies. The forced warm air systems offer a new method and much better means of providing thermal
support.
•
Metabolic and endocrine support is needed by some at-risk patients due to immaturity or disease.
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Inadequate glycogen storage or availability
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Adrenal insufficiency
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Excessive physiological demands
Delayed recovery from anesthesia
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Anesthetic overdose
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Inadequate elimination or metabolism
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MDR-1 Mutations, Heterozygous or homozygous, Genetic testing is available
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Hypothermia
•
Debilitation
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Neurological deterioration
Management of delayed recovery
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Physiological support
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“SOP” - monitor, evaluate, diagnose, treat
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Facilitate elimination or metabolism
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Reversal of anesthetic drugs only when appropriate
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Pet Food:
Interpreting Labels and Understanding Regulations
Callin Heinze, MS, VMD, DACVN
Cummings Veterinary Medical Center at Tufts University
North Grafton, MA
Pet food labels serve as marketing devices, as legal documents, and sources of limited nutritional information. Unfortunately, these
purposes are often at odds as the current regulatory environment reflects the evolution of companion pet diets from livestock diets
rather than from human foods. It is important for veterinarians to understand what information is legally required to be on a label and
how to use this information to help clients make informed decisions regarding pet foods.
Regulation
In the US, pet foods are regulated both nationally and at the individual state level. Two main organizations are involved: the Food and
Drug Administration (FDA) and the Association of American Feed Control Officials (AAFCO). The FDA regulates pet foods
nationally through the Center for Veterinary Medicine (CVM). The Federal Food, Drug, and Cosmetic Act (FFDCA) requires that pet
foods, like human foods, be “pure and wholesome, safe to eat, produced under sanitary conditions, contain no harmful substances, and
be truthfully labeled”.
The FDA has some basic requirements for pet food labels: proper identification of the product, net quantity (weight) statement,
name and place of business of the manufacturer or distributor, and an ingredient list ordered from most to least, based on weight. The
FDA is also responsible for evaluating product health claims on labels – i.e. hairball prevention, urinary tract care, etc. The FDA has
enforcement power to pursue violations in labeling and manufacturing processes, including prohibiting the sale of certain products and
even enforcing jail terms for individuals repeatedly found to be in violation.
AAFCO is not a governmental regulatory organization; however, its members are all US state or federal government officials that
meet to review the current knowledge and regulations on pet food and make recommendations. AAFCO committees may be advised
by outside individuals from industry and academia. AAFCO is responsible for setting guidelines not just for dog and cat food, but for
feeds for all domestic animals. It is important to keep this in mind as some of the information in their annual publication, especially
some ingredient definitions, may apply to livestock rather than to pets.
The states adopt AAFCO regulations as their own to varying degrees and enforce them through their state feed control officials.
AAFCO itself has no enforcement power and also does not “approve” pet foods. AAFCO publishes yearly guidelines which can be
purchased online from their website. AAFCO publications include guidelines for pet food labels, ingredient definitions, tests of
nutritional adequacy, additives, and recommended nutrient levels in diets for various life stages of cats and dogs.
Key elements of a pet food label
Manufacturer or distributor info – all labels must include an address to contact the manufacturer or distributor. Although a
telephone number, email address or website address are not required to be on the label, it is best to avoid companies that do not
include at least one of these methods of contact as it is often impossible to get timely information by mail only. Beware of foods that
just list the store as the manufacturer – big box stores and grocery stores (i.e., Safeway, Whole Foods, Trader Joe’s, WalMart) do not
make their own food. It can be very difficult to get any information on these diets by contacting the corporate office of the store that
sells them and the stores are often unwilling to release information about the true manufacturer.
Nutritional adequacy statement – AKA “AAFCO statement”. All pet foods marketed in states adopting AAFCO guidelines must
have one of the following statements clearly printed on the bag:
1. This product is intended for intermittent and supplemental feeding only
2. Animal feeding tests using AAFCO procedures substantiate that Product X provides complete and balanced nutrition
for [species, life stage]. (Life stages include maintenance, growth, gestation and lactation and all life stages)
3. Product X provides complete and balanced nutrition for (species, life stage), and is comparable in nutritional adequacy
to a product with has been substantiated using AAFCO feeding tests.
4. Product X is formulated to meet AAFCO nutrient profiles for [species, life stage]
Diets that are “formulated to meet” do not have to be fed to any animals before being put on the market. Additionally, diets that
fail AAFCO feeding trials could technically still be marketed under a “formulated to meet” statement. Feeding trial protocols are
detailed in the AAFCO guidelines and specify that a certain number of animals are fed the diet for a set time period, that data is
collected on weight, blood values, reproductive performance and growth (growth or all life stages), and that no detrimental effects are
noted. Feeding trials may also used by manufacturers to collect digestibility data for foods although this information is not required.
While most diets that have passed feeding trials are also “formulated to meet”, they do not have to be. For example, Hill’s Prescription
Diet canine k/d has passed feeding trials for adult maintenance but is too low in protein and phosphorus to carry a “formulated to meet
AAFCO” statement.
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The most recent recommendations include a variation of the statement for large and giant breed puppies. In the future, all diets
with an AAFCO statement for growth or all life stages will need to indicate: “not including growth of large size dogs (70 lbs or more
as an adult)” or “including including growth of large size dogs (70 lbs or more as an adult)”
Calorie content
Now required on all food and packaged treats; previously not required unless a diet is marketed as “lower calorie” or
“light”. Calories must be in kcal/kg as well as kcal/cup or can.
Ingredient list
Ingredients must follow standard definitions (in AAFCO publication) and be listed in order of weight. Moisture is included in the
weight, so high moisture foods (like meats and fresh vegetables) will be heavier than drier foods (grains, meat meals). Exact amounts
are not included and cannot accurately be estimated from the ingredient list.
Ingredients lists are often subject to marketing whims and do not necessarily reflect the quality or nutritional adequacy of
a diet
They may, however, reflect expense in the case of unusual (and unnecessary) ingredients such as quail eggs, pomegranate, and bison.
Product name
There are strict rules for naming products. For example, “beef for dogs” must legally contain >95% beef on a dry matter (DM) basis
and >70% as fed. “Beef dinner”, “beef platter”, and “beef entrée” require that beef be >25% total weight. “With beef” means that the
product is at least 3% beef. “Beef flavor” generally means that there is less than 3% beef. Moisture may not exceed 78% unless the
terms “in sauce”, “in aspic” or “in gravy” appear in the product name.
Designator
“Dog food”, “for cats” – states diet use
Feeding guidelines
Usually based on standard maintenance energy requirement (MER) equations with a safety margin. Animals should be fed to meet
caloric and nutrient needs to maintain an ideal body condition, regardless of the feeding directions on the label. However, be aware of
patients that are consuming less than 80% of the recommended amount for their ideal weight as they may be consuming inadequate
nutrients and probably should be fed a diet with a lower energy density.
Guaranteed analysis (GA)
Only minimum protein, minimum fat, maximum fiber and maximum moisture must be included unless the manufacturer adds
statements such as “now with omega-3s” or “with added taurine” to the packaging, in which case the amount of the specified
ingredient must also be listed. The amounts listed are “as fed” amounts, meaning as the food comes out of the package or how it is
intended to be fed. These “crude” amounts may vary from the actual amounts in the food and cannot easily be used to compare two
different diets without conversion of the values to standardized units (such as grams per 1000 kcal; Mcal).
Net weight
The amount of food in the bag. Keep in mind that the caloric density is more important than the weight of the food when determining
feeding costs as foods can vary in caloric density (35 pounds of one food may have the same calories as 18 pounds of another).
Comparing pet food nutrient distributions using the label
The information included in the GA is not always very useful when it comes to making decisions about which diet may be appropriate
for which patient. It is best to obtain a typical analysis from the manufacturer. At the very least, it is necessary to convert the GA
values to values that are standardized for fiber, moisture and caloric density to directly compare diets.
An accurate way to compare pet foods is on a metabolizable energy (ME) basis. Metabolizable energy refers to the percentage of
the calories of a diet that come from protein, fat, and carbohydrates, taking into account both fiber and moisture. There are several
references that show detailed methods [see ‘Further information’, below] for calculating ME for pet foods based on the GA or typical
analysis (obtained from manufacturer, actual amounts rather than min and max) as well as online calculators such as the one at:
https://secure.balanceit.com/tools/_gaconverter/) To calculate the ME most accurately, the ash content of the diet is required and
usually must be obtained directly from the manufacturer.
Other nutrients can be compared between diets by expressing them on an energy basis – i.e., grams per Mcal (1000 kcal). Protein,
fat and carbohydrate concentrations can also be expressed this way, but it may be less intuitive to clients and technical staff. These
units take into account the fact that nutrient requirements are related to body size and that animals of a certain size are expected to
consume a similar amount of calories. There is concern that an animal that needs substantially less calories than average for its size
may thus become nutrient deficient. For this reason, diets designed for animals with lower energy requirements should contain higher
concentrations of nutrients per calorie to compensate for the lower caloric intake. Likewise, high energy diets should contain
comparably lower concentrations of nutrients per calorie to avoid excesses.
Evaluating pet foods
The American Animal Hospital Association has recently published nutrition guidelines which include assessment of commercial pet
foods: www.aaha.org/professional/resources/nutritional_assessment.aspx
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WSAVA also has information on choosing pet foods in their Nutrition Toolkit: www.wsava.org/nutrition-toolkit
Some additional things to consider are listed below.
Label
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Is appropriate contact information listed for the manufacturer – i.e. toll free phone number or web address?
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Ingredient list – does the patient have any known allergies or intolerances to certain ingredients? Is the company using
unnecessarily expensive or exotic ingredients as a marketing ploy?
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“Quality” descriptors – although commonly used, the terms “premium”, “super premium”, “ultra premium”, and
“gourmet” have no legal meaning and can be used by any manufacturer without any burden of proof
•
Health claims – all health claims on diets must be evaluated by the FDA. However, it is not uncommon to see
unsubstantiated health claims on labels and in marketing materials. If a health claim seems questionable, call the
company and ask for written documentation of the claim (i.e. peer-reviewed publications).
Marketing materials
Beware of:
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Unverifiable claims – “prevents cancer”, “takes years off your dog”, “increases energy and vitality”
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Testimonials in lieu of data – ask for documentation of any claims made, remembering that in evidence-based medicine,
testimonials mean little and are easily faked.
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Inaccurate or misleading nutritional information – i.e. incorrect definition of by-products or other ingredients,
misspellings, and propagation of myths such as: grains cause allergies or are “fillers”, high fat diets cause heart disease
in dogs, flax is good source of omega-3 fatty acids for cats, etc.
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Reliance on the “no list” or bashing other products to market a product
Other factors
•
Knowledge of employees when you call on the phone – can they provide requested information in a timely manner?
Further information
Dzanis, D. A. (2008). "Understanding Regulations Affecting Pet Foods." Topics in Companion Animal Medicine 23(3): 117-120.
Zicker, S. C. (2008). "Evaluating Pet Foods: How Confident Are You When You Recommend a Commercial Pet Food?" Topics in
Companion Animal Medicine 23(3): 121-126.
Hand, M. S., C. D. Thatcher, et al., Eds. (2010). Small Animal Clinical Nutrition, 5th Edition. Topeka, KS, Mark Morris Institute.
www.fda.gov/AnimalVeterinary/Products/AnimalFoodFeeds/PetFood/default.htm
www.aafco.org/
http://talkspetfood.aafco.org/
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2th-1-1 Dental Emergency!
Trauma to the Oral Cavity
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
There are many conditions that are considered an emergency in day to day veterinary medicine. It is common that trauma to the head
and face will likely cause some oral cavity damage. Although oral emergencies are not life-threatening, many head and face injuries
are painful and should be dealt with as soon as the patient is stabilized. It is important that the veterinary team is able to identify and
treat these conditions and return our patients’ to a healthy functional state.
Soft tissue trauma
Oral lacerations, lip injuries, burns, hard & soft palate defects, foreign bodies, electrical injuries, gunshot wounds. Primary wound
management of these types of trauma would consist of hemorrhage control, de-contamination with saline, surgical exploration,
debridement and closure if possible.
Hard palate
Hard palate defects can be acquired from any of the above mentioned causes. High-rise syndrome in cats can occur when the cat has
fallen from a great distance and usually results in a midline palatal fracture. This can be repaired with gentle reduction and suturing of
the defect.
Tooth trauma
These injuries are common and may affect the tooth itself or encompass the periodontium as well. Generally caused by blunt force,
hit-by-car, or chewing on hard objects.
Non-vital tooth (NV)
A tooth that has suffered a direct trauma that has not broken the tooth but has caused the pulp to swell and die. Tooth may be pink or
gray in color and does not trans-illuminate. Treatment of these “ticking time bombs” would be root canal therapy or extraction. No
“wait and see” approach.
Crown fractures
Complicated crown fracture( FX/CCF)
A fracture that exposes the pulp of the tooth. This could allow inflammation, infection, and necrosis of the entire “live” part of the
tooth. Potential treatments would be root canal therapy, vital pulp therapy (if the fracture is noticed within 4 hours on a young tooth),
or extraction
Uncomplicated crown fractures (FX/UCCF)
A fracture that has penetrated the enamel but not the pulp but has exposed the dentin. This would allow bacteria to travel through the
dentinal tubules and could result in inflammation, infection and necrosis of the pulp. Treatment with a restorative material would seal
the dentin and protect the tooth. Monitoring of these teeth at regular intervals is imperative to further evaluate for endodontic disease
after restoration.
Crown/root fractures
Crown/root fractures can be complicated or uncomplicated and depending on the location of the fracture and how far it extends below
the gingival margin, can be treated with endodontics or exodontics. It the fracture does not extend beyond 5 mm below the gingival
margin, endodontics and restoration can be performed. If the fracture is 5mm or greater beyond the gingival margin and alveolar
bone, extraction is the only treatment
Root fractures
Fractures may occur in a horizontal, vertical or oblique direction. Fracture level determines the treatment options. A more apical
horizontal fracture is more favorable for treatment with wire/acrylic stabilization whereas a vertical fracture or a horizontal fracture
near the gingival margin would require extraction.
Periodontium trauma
Damage to the periodontium can cause the tooth to loosen in the alveolus. The maxillary canines and incisors are commonly affected.
Subluxation
Increased mobility of the tooth within the alveolus in a horizontal motion with no vertical movement. Tooth can be monitored
radiographically at the time of trauma and at 6 month intervals for pulp vitality and may require future endodontic treatment.
Luxation
Movement in a vertical (intrusion/extrusion) or lateral direction. Intrusion is where the tooth is pushed apically and embedded into the
alveolar bone and may appear shorter than the surrounding teeth. Extrusion occurs when the tooth is dislocated vertically from the
alveolus and appears longer than the adjacent teeth. Lateral luxation manifests when the trauma pushes the crown in a palatal or
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buccal direction and a fracture occurs in the buccal bone plate. Tooth replacement and stabilization with acrylic/wire splint and
endodontic therapy after healing.
Avulsion
A tooth that has been completely removed from the alveolus. A healthy tooth needs reimplantation and fixation within 30 minutes.
The avulsed tooth should be kept in saline or milk and not allowed to dry and only handled by the crown so as not to remove any of
the periodontal membrane. The tooth is replaced in the alveolus and an acrylic/wire splint is placed. Endodontic therapy is always
necessary in these cases due to the disruption in the blood supply to the tooth.
Jaw fractures
Jaw fractures of the incisive, maxillary, nasal, and mandibular bones are commonly caused by car accidents but may also be a result of
severe periodontal disease especially in the mandibular premolar/molar area. Indications for jaw fracture repair are malocclusion,
instability, facial deformities, or obstruction or communication with the nasal cavity. A successful jaw fracture repair relies on the
location of the fracture, maintaining occlusion, simple repair technique with minimal implants and avoidance of tooth roots and apical
areas. Extraction of diseased teeth may be necessary. Repair techniques include traditional use of an external fixator or tooth
appliances such as interdental wire, acrylic splints or tape muzzles. Healing should be confirmed radiographically in 4-6 weeks.
Mandibular fractures are the most common fractures that occur in the canine patient. Due to the biomechanics of jaw opening and
closing mandibular fractures can be classified into two categories:
Favorable fracture
Fracture line runs from the occlusal aspect rostrally to the ventral mandible (caudodorsally). The masseter, pterygoid, and termporalis
attach at the caudal end of the mandible and create compression and alignment on fracture lines in this area.
Unfavorable fracture
Line runs from the occlusal aspect caudally to the ventral (caudoventrally) mandible.
The digastricus muscle is involved in jaw opening and therefore creates tension to “pull” the rostral mandible down and caudally
whereas the pterygoids, masseter & temporalis are used for jaw closure and exert upward force on the distal segment and displace the
fracture fragments.
Mandibular symphyseal separation
Can occur in cats and dogs but is more common in the cat. Iatrogenic fracture during mandibular canine extraction is potential cause
for symphyseal separation or fracture. Typically this fracture can be treated with circumferential wiring behind the canine teeth
stabilize the segments.
TMJ trauma
TMJ luxation is usually related to head trauma that creates a separation of the mandibular condyles from the articular surfaces of the
temporal bone and the mandibular fossae.₁ Typically the patient will present with an inability to close the mouth or may have lateral
deviation of the mandible. Radiographs are taken to evaluate for increased space within the TMJ. The luxation can be reduced by
using a fulcrum between the maxillary and mandibular molars while closing the mouth and lever the condylar process in a
ventrocaudal direction. A tape muzzle can then be applied for 2-3 weeks to prevent re-luxation.
Most dental emergencies will require treatment after initial stabilization of the patient. The veterinary team will be challenged
with these emergencies and must be ready to diagnose and provide initial management of injuries. Referral to a dental specialist for
treatment will be likely for a more favorable outcome.
References available upon request.
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Dirty Mouth? Clean it up!
A Complete Periodontal Cleaning
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
A complete periodontal cleaning is required to remove the "disease" elements of periodontitis. This includes removal of bacterial
laden supra(above) gingival and sub(below) gingiva calculus and plaque. The intent of professional dental cleaning is to prevent
periodontitis, but most patients already have significant disease. The terms “prophy”, “prophylaxis”, “dental” are misused as very
rarely are we actually preventing periodontitis. Dental procedures must be performed by a licensed veterinarian, a credentialed
technician, or a trained veterinary assistant under the supervision of a veterinarian in accordance with state or provincial practice acts.
Practice acts vary from jurisdiction to jurisdiction, and the veterinarian must be familiar with those laws. Surgical extractions are to
be performed only by trained, licensed veterinarians.
In 2013 AAHA published the Dental Care Guidelines for Dogs and Cats, which are guidelines for the practice of companion
animal veterinary dentistry and include the following steps.
Admission
Upon admission of the patient for its procedure, client contact information and consent for the procedure is obtained. This allows the
client to be reached if any oral pathology is found while the patient is under anesthesia. No additional procedures should be
performed without informed consent of the owner. Any patient history should be identified as well as a brief discussion of future
homecare may be warranted if time permits.
Anesthesia
The appropriate anesthesia protocol and fluid support is decided upon based on the pre-anesthetic examination, age of the patient, lab
work results, general health, etc. as well as anticipated duration and pain level beyond a "routine" cleaning. A protocol for multimodal pain control should be considered ahead of time and could include use of an opioid for pre-anesthetic sedation which can
decrease the amount of inhalant anesthetic agent used. A CRI can be considered for some patients as this also can decrease the
amount of inhalant required. This combined with intra-operative pain medication of local and regional blocks and post-operative drugs
are ideal for a multi-modal approach from the beginning.
Patient positioning, monitoring & care
After the patient has been given an anesthesia induction agent, an endotracheal tube with a properly inflated cuff is placed to prevent
fluid or debris from entering the trachea and lungs, and the patient is maintained under general anesthesia. Gauze pads can then be
placed in the oropharynx for additional protection if suction is not available. These gauze pads need to be changed frequently
throughout the procedure and always removed before the patient is recovered from anesthesia.
For most procedures it is adequate to position the animal in lateral recumbency. Virtually all of the cleaning, polishing,
radiography etc, can be accomplished in this position. Dorsal recumbency is another accepted position as the animal is placed into
position only once and is not moved for the entire procedure. As with any new positioning technique it will take some time to practice
and everyone has their preference.
The patient is then connected to appropriate monitors including blood pressure, pulse oximeter, electrocardiogram etc. Patient
parameters are checked every 10-15 minutes and should be noted on an anesthesia worksheet of some type. Patient body temperature
is especially important in the dentistry patient as they rapidly become wet from the water spray, and this can drop very quickly if
initial steps are not taken to keep the patient warm. The patient is placed on a hot water circulating blanket or a type of forced hot air
device. Towels can be placed under the patients head and around the body but must be changed to keep the patient as dry as possible.
Oral exam
Before you begin your periodontal cleaning a brief oral exam is performed including the tongue, soft and hard palate, pharynx, tonsils,
buccal mucosa, lymph nodes and the extra-oral facial features as well as determining the occlusion of the animal. Any deviation of
the normal occlusion pattern, in which the lower incisors occlude palatally to the upper incisors and the upper and lower premolars
and molars occlude in an interdigitating, shearing relationship with the maxillary teeth buccal to the mandibular teeth are noted.
The amount of calculus, plaque, gingivitis, pocket formation and furcation exposure are graded prior to the beginning of cleaning
and can be repeated several times during the procedure. This is noted on the dental chart which should include a diagram of all the
teeth in buccal, occlusal, and lingual views so that different pathology can be properly charted at each site. Dental charting should be
uniform within the clinic and have an abbreviation key available for reference. The AVDC website has all the dental abbreviation
recommendations and this can be adapted to your clinics’ needs.
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Gross calculus removal
To begin your cleaning the heavy calculus is removed with tartar removal forceps or regular extraction forceps. The tips of the
forceps are carefully placed around the tooth just coronal to the gum line. Care must be taken to avoid the delicate gingival tissue, as
it can become trapped in the forceps and damaged severely. The handles are then squeezed until the thicker layers of tartar "crack" off
of the tooth. It is not necessary to remove every piece of tartar with the forceps as this will be done with the use of power and hand
instruments.
Radiographs
Dental radiographs are a very useful tool in veterinary dentistry today. Full mouth radiographs are a preferred method due to the
discovery of pathology that may have gone undetected. Radiographs are taken of any teeth with pockets greater than 2-3 mm,
furcation exposure, mobility, fractures, or oral masses. It is also important to take radiographs of any "missing" teeth as it is common
to find retained tooth roots or embedded teeth if there is no previous record of extractions at that site. Dental radiographs can be taken
with dental film or a digital sensor. Digital radiography has sped up the process time of traditional film and provides excellent detail
in a short amount of time as well as being less expensive in the long run. After the radiographs have been taken a treatment plan can
be discussed with the client.
Power scaling
The remainder of the calculus and plaque is removed with power equipment and hand instruments. The three types of power scalers
are piezoelectric, ultrasonic and air driven. The rotational vibration and water spray cavitation at the head of the scaler is what
removes the additional calculus and adhered plaque from the tooth surfaces. The type of power scaler does affect how to use the
direct sides of the scaler tip and are in the operator manual of individual units. This should be known prior to use of the equipment. A
general systematic approach is used to clean each tooth in each quadrant. You should clean in the same pattern every time so as to
decrease your chances of missing any surface. The scaler tip is then placed near the gingival margin and is moved across the tooth in
a broad sweeping motion as you move coronally. Try not to inadvertently "lift up" and replace the tip any more than necessary as this
can cause pitting of the enamel. Also do not spend more time than is necessary to clean the tooth as thermal damage can occur with
prolonged contact. Specific power scaler tips are used for subgingival and supragingival scaling. A universal tip can be used above
and below the gum line and is the best all-around tip for general use.
Hand instrumentation
Power scaling is always followed by hand instrumentation as a way to "check" for deposits of calculus and plaque left behind. Hand
scalers are always used above the gum line on the crown of the tooth. Scalers generally have 2 sharp cutting edges and a pointed tip.
These sharp edges, if used under the gum line, can cause severe damage to the gingival tissues. The most obvious areas that require
hand scaling are the developmental groove of the upper 4th premolar and other fissures. The hand scaler tip can be used at a direct
angle to the tooth whereas the power scaler is never allowed to be used at a right angle to the tooth! The curette comes in many
different styles and angles but because it has a rounded end and backside it can be safely used under the gum line. The curette is a
more fragile instrument and should not be used as a scaler! Regardless of whether you are using a scaler or a curette it is important to
know which part of the instrument is doing the work. The "toe" (curette) or "tip" (scaler) is the very point of the instrument, then the
cutting edge and the face. The toe and rounded back of the curette can be gently inserted under the gum line. It is then tilted up at
approximately 15-20 degrees until the cutting edge is engaged and then in a quick long pull stroke of the instrument as it is moved
coronally. This is repeated until the tooth is smooth. To remove and debris in the subgingival soft tissue the curette is reversed and
the cutting edge is moved along the gingival tissue. This is basic root planing and subgingival curettage.
Detection of missed calculus and plaque
After all calculus and plaque has been removed a disclosing solution can be applied to the teeth to identify anything that has been
missed. This is generally a red colored solution and many find it to be too messy. The air-water syringe can be used to air dry the
tooth and look for any debris that may have a chalky white appearance. The air can be directed under the gum line to look for any
additional debris that may be hiding.
Repeat of oral exam & plan for further treatments
The oral exam can then be repeated to include further grading of gingivitis, measuring of periodontal pockets, checking for tooth
mobility, missing teeth, furcation exposure, fractured or traumatized teeth or any other abnormalities. A plan for further diagnostics
and treatment can then be established.
Polishing & final rinse
After further procedures are completed the teeth can be polished using the slow speed handpiece and a generous amount fine grit
polishing paste. The rpm of the handpiece should not exceed 5,000 as this can thermally affect the tooth. Time spent on each tooth
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should be kept to a minimum for this reason as well. The oral cavity is then rinsed and dried and any additional debris, fluid and
blood is removed. The oropharynx gauze pads must be removed, and the patients faced is cleaned and dried. The patient is then
recovered from anesthesia and temperature is continually monitored as well as the need for additional pain medication. Once the
animal is extubated and safe in his cage, cleanup and instrument care can take place.
Discharge & follow up
Discharge of the animal usually includes the patients’ post-op instructions, radiographs and photographs and should be printed and
explained to the client. Clients are advised of any dietary needs, post-op medications and recheck exams. A two week follow up
appointment is ideal to evaluate healing of the oral cavity after treatment and allows the client to focus on homecare
recommendations. This way they are not bombarded with too much information on the same day as the procedure. It is also
recommended to have a six month complimentary oral exam to re-evaluate the patient and address any concerns. Clients should also
be aware of the advantages of regular home care. These recommendations should include daily tooth brushing, oral rinses, dental
diets and approved dental chews. Home care should be tailored to the individual patients' lifestyle and temperament as well as how
willing the client is to follow through. Recommend brushing only the teeth they want to save, and see what kind of response you
get!!!
702
Getting Owners to Consent to Dentistry in Your Practice
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
Your patients need quality dental care and the best way to convey this to your clients is by properly educating yourself and informing
the client of their pets’ dental health care needs. When you take the time to educate yourself on the subject and understand the
pathology and physiology and the effects on the animal, you will then be able to share this information with the client and provide a
tremendous benefit to the patient. If you are informing the client of the proper care with passion, enthusiasm and sincerity they are
more likely to accept your recommendation. We know that somewhere between 65-80 % of cats and dogs, based on various studies,
have some form of periodontal disease. We can incorporate these findings at yearly wellness and vaccination appointments and
improve our dentistry compliance.
All can be lost if the whole “team” is not supplied with the proper knowledge to inform the client. There are many sources of
education available to the veterinary team to improve their understanding of veterinary dentistry. Development of the practices’
dentistry message can help to solidify the information you want to deliver. If only one person says something about dental care and is
not backed up by the rest of the staff, the client is less likely to take you seriously. Therefore it is necessary to train anyone who has
contact with the client to deliver the same message. You want your staff to be able to give intelligent answers to your clients’
questions and concerns. If your clients see that everyone in the practice believes dentistry is important, the client will follow your
prescribed oral health plan
Hearing your dentistry message can start with the first phone call. The receptionist can be the first to mention dentistry to the
client. We ask previous history of vaccinations, fecals, and heartworm but never ask when the last dentistry was performed. This can
also be included on your hospital check in form. The second time they hear your dentistry message can be upon checking the client
into the examination room. Technicians should be comfortable “flipping the lip” and assessing and showing the clients their pet’s
periodontal issues. Be descriptive in letting the client know what is going on with their pets’ oral health and use pictures and
handouts which describe different periodontal issues. Next comes the doctors’ role in affirming what the technician has assessed and
providing the client with a treatment plan. Show them what you are finding and what needs to be done and relay to the client that
there is a sense of urgency. If you see a cat with a tooth resorption lesion, press gently on it with a q-tip to convey the pain aspect to
your client. Your client relates to this more than anything! Most clients are willing to help their pets once they are aware of the
problem. Then upon check out the receptionist can review the oral health findings and ask them to schedule. Hold each other
accountable for your recommendations. When the technician comes out of the exam room the doctor can ask “did you talk about
dental disease?” and the tech says “no” then the doctor can ask the technician to go back in and talk about it and vice versa!
Using vague terminology such as a “dental” or “prophy” gives the client an impression that all dental procedures are alike and
simplifies the actual work that is being performed. It is highly unlikely that the pet requires a scale and polish as a “prophy” defines,
as this is a treatment for mild to moderate gingivitis only. Explaining that your procedure is more of a comprehensive oral health
assessment and treatment (COHAT) will reinforce the idea to them that there is much more involved. You can explain that a thorough
oral examination is required to assess the pets periodontal health and appropriate treatment plan. It is never “just a dental”!
So when you get phone shoppers that are asking “how much to clean my dog’s teeth?” you can start from the beginning of your
dentistry message and have them come in for a comprehensive oral health assessment. Providing an itemized estimate can only be
provided after doing an oral examination. Explain why this is necessary and inform the clients of the level of care their animal will
receive and most clients are therefore willing to pay for these services. There should be a dental services fee schedule of itemized
procedures. You need to be willing to charge for your services and not lump them into a set fee.
Set goals and track them! Make it a goal to get one person a day to say “yes” to dentistry. You have to track your percentage of
procedures to see if you are making improvements. Celebrate your successes!
Devote time at team meetings once a month to discuss a planned agenda. Each month should be a different topic such as
January=marketing, February=client education materials, March=steps to a comprehensive oral health assessment and treatments, etc.
Be prepared to expand your training through further education and hands on learning as well as upgrading your equipment and
instruments to provide a high level of care for your patients.
The lack of dental training, poor equipment and inadequate amount of time leads to frustration and a disinclination to do what is
necessary. Develop standard operating procedures for your dentistry patients. Don’t hurry, dentistry takes time! Dental instruments
should be treated like any other surgical instruments and maintained properly to get the return on your investment. The use of proper
equipment can pay for itself in the time savings per dental procedure, increased procedures performed, and advertising you are ” set
up” for a higher level of dentistry services. Use your expanded knowledge and set yourself apart from other practices.
Ignoring or overlooking the oral health needs of our patients is not only a missed opportunity to serve the client and their pet better,
but a lost opportunity to profit the practice.
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Run the numbers
If 75% of dogs and cats have some form of periodontal disease by the time they are 3 years old these are opportunities that present
themselves in your practice everyday, no external marketing needed!
•
10 patients/day
•
5 days/week
•
50 weeks/year
•
=2,600 patients per year
•
Of these patients 75% with disease=1,950 patients
•
Client compliance of 50%= 975 patients per year
•
975 patients at $350.00=$341,250!!! WOW!!!
•
That would =3.9 “yeses” per day
So think about if you had atleast one yes per day that would still be $87,500!
Can you afford digital dental x-ray?
•
Cost of x-ray unit, sensor, software= $12,000
•
975 patients X $85 for full mouth series=$82,875=yes
•
300 patients X $85=$25,500=yes
Every year will typically generate the same if not more income so continual return on investment.
That’s from x-rays alone not to mention the added treatments you will generate. There is so much room to grow this area of the
practice, but it takes dedication!
704
No Bones About It!
An Intro to Oral Anatomy
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
A general understanding of anatomy is necessary to determine the relationship of the structures in the oral cavity and how they relate
to the bones of the skull. The main structures in the oral cavity are the teeth, periodontium, tongue, soft and hard palate.
Bones
The skull is comprised of the cranium and the face
•
Cranium- protects the brain
•
Frontal, Parietal, Interparietal, Temporal, Ethmoid, Occipital, Sphenoid
•
Face- composed of the oral, nasal and ocular cavities
• Lacrimal, Temporal Process, Nasal, Maxilla, Incisive, Pterygoid, Ventral Nasal Conchal, Mandible
3 primary skull types
•
-Mesaticephalic- average head (laborador retriever, domestic shorthair cat)
•
Brachycephalic- shortened face (Pug, Persian)
•
Dolicocephalic- elongated face and nose (greyhound, Siamese)
The primary bones of the oral cavity are the maxilla, incisive and mandibles, they support the teeth with alveolar bone and provide
attachment for the muscles and protection to the vessels and nerves.
Incisive bone
This is the rostral bone of the maxilla and houses the incisors
Maxilla
This supports the upper teeth of canines, premolars and molars.
•
Joins with the palantine bones to create the hard palate.
•
Infraorbital foramen-canal in which the infraorbital nerve, artery and vein pass and innervate the maxillary teeth as it
branches into three sections reaching the maxillary molars, premolars, canines, and incisors
•
Maxillary foramen- opening at the caudal aspect of the infraorbital canal
Mandible
Two separate, symmetrical bones that join at the rostral midline (mandibular symphysis), supports the incisors, canines, lower
premolars and molars.
•
Mental foramen- located on the buccal aspect and apical to the second and third premolar respectively. The mental
nerves pass through these foramen and innervate the lower lip and chin.
•
Mandibular foramen- located on the lingual aspect of the ramus. The inferior nerve passes through the foramen as in
enters the mandibular canal and innervates the mandibular teeth.
•
The ramus of the mandible is the perpendicular portion of the bone
Teeth
Tooth formation originates from the mesenchymal cells along the epithelium of the maxilla and mandible. Within this follicle the
tooth bud is formed. Next is the cap stage when the tooth cells begin to develop and start to develop the blood, nerve and lymphatic
vessels that will become the pulp. The bell stage is the beginning of the tooth structure components of dentin and enamel. The final
stage is the crown/eruption phase when the odontoblasts and ameloblasts aid in the formation of enamel.
Tooth eruption times:
Puppies: deciduous
Kittens: deciduous
-Incisors- 3-4 weeks of age
-2-3 weeks of age
-Canines- 3 weeks of age
-3-4 weeks of age
-Premolars- 4-12 weeks of age
- 3-6 weeks of age
***no deciduous molars***
Puppies: permanent
Kittens: permanent
-Incisors- 3-5 months of age
- 3-4 months of age
-Canines- 4-6 months of age
- 4-5 months of age
-Premolars- 4-6 months of age
- 4-6 months of age
-Molars- 5-7 months of age
- 4-5 months of age
Each species has a distinct dental formula and most mammals have a deciduous and permanent dentition. Dogs and cats have 4
types of teeth incisors, canines, premolars and molars.
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Deciduous canine dental formula (28 teeth)
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Maxilla: incisors (6), canines (2), premolars (6), molars (0)
•
Mandible: incisors (6), canines (2), premolars (6), molars (0)
Permanent canine dental formula (42 teeth)
•
Maxilla: incisors (6), canines (2), premolars (8), molars (4)
•
Mandible: incisors (6), canines (2), premolars (8), molars (6)
Deciduous feline dental formula (26)
•
Maxilla: incisors (6), canines (2), premolars (6), molars (0)
•
Mandible: incisors (6), canines (2), premolars (2), molars (0)
Permanent feline dental formula (30)
•
Maxilla: incisors (6), canines (2), premolars (6), molars (2)
•
Mandible: incisors (6), canines (2), premolars (4), molars (2)
•
**Cats typically are missing their first upper premolars and first and second lower premolars**
The structural components of each tooth consist of:
•
Crown-visible portion above the gum line, comprised of dentin and covered with enamel. Houses the pulp chamber.
Subject to wear, trauma and discolorations.
•
Root(s)- below the gum line, comprised mostly of dentin and covered with cementum and houses the root canal.
Attached to the alveolar bone by the periodontal ligament. The tip of the root is the apex with an apical delta consisting
of several openings leading to the root canal.
•
Enamel-hardest substance in the body, inorganic mineralized tissue covering the crown, no reparative capacity,
approximately 1 mm depth on an adult dog, much less than humans
•
Dentin- inorganic porous tubules comprising the majority of the adult tooth, below the enamel, yellowish color, much
softer than enamel
o Primary Dentin- initial formation prior to eruption
o Secondary Dentin- continues to develop throughout the life of the tooth
o Tertiary Dentin- a reparative dentin due to trauma, darker brown or yellow color
•
Pulp- vital portion of the tooth consisting of blood, nerve and lymphatic tissue, lined with odontoblasts, connects with
the periodontal ligament at the root apex. Coronal portion=pulp chamber; Root section=root canal.
•
Periodontal Ligament- consists of collagen fibers, blood vessels, and nerves that attach to the cementum on tooth root
and connect to the alveolar bone. Allows sensations such as heat, cold and pressure.
•
Cementum- mineralized connective tissue covering the root of the tooth, begins at the cement-enamel junction (CEJ),
dull and pitted and softer than enamel, dentin, or bone, has reparative and resorptive properties, periodontal ligament
fibers attach to the cementum and provide retention of the root in the alveolar bone
•
Alveolar Bone- ridges of the jaw that support the teeth, the crest of the alveolar bone is approximately 1 mm below the
CEJ.
Types of teeth
Incisors: small single rooted teeth located in the incisive bone. Used primarily for grooming and picking up objects. Canine and
felines have 6 maxillary and 6 mandibular incisors.
•
Canines: large single rooted “fang” teeth.
•
Premolars: multi-rooted teeth used for mastication
•
Molars: multi-rooted teeth used for mastication
Periodontium
Gingiva
Soft tissue that surrounds the teeth and covers the alveolar bone
•
Sulcus- unattached tissue at the junction of the free gingiva and the tooth, normal sulcus depth in dogs is approximately
3 mm and cats is 1 mm
•
Attached gingiva- protects the alveolar bone and joins the oral mucosa at the mucogingival junction/line (MGL)
Oral mucosa
Mucous membrane that forms the lining of the oral cavity from the mucogingival line to the junction of the lips. The vestibule is the
space between the alveolar ridge and the cheeks and lips.
Tongue
The functions of the tongue are to taste, lap liquids, move and form food and aid in swallowing.
706
Hard and soft palate
The “roof” of the oral cavity, covered by soft tissue (palantine rugae),
•
Hard palate- consists of the incisive, maxillary and palantine bones
•
Soft palate- movable, smooth fold of tissue that connects the oral cavity the pharynx
For our purposes this is a very condensed version of the anatomy of the structures related to the oral cavity. A general
understanding of the associated anatomy will aid every technician in providing comprehensive treatment for the patient. With time
and practice, anatomy will become second nature to the veterinary technician.
707
Save a Tooth!
Advanced Periodontal Treatments
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
The primary goal of any dentistry is to leave the patient with a healthy and comfortable oral cavity. Most practitioner’s also want to
salvage as many teeth as possible. Sometimes this is attainable with advanced dental therapies to treat periodontic and endodontic
disease. As technicians we are responsible for alerting the veterinarian to observed pathology and assisting in needed treatments. We
must be aware and anticipate how these therapies are performed to facilitate these treatments. We must also educate the client of the
commitment to follow up care prior to undertaking these types of cases.
Periodontal disease
The treatment of periodontal disease is designed to manage the patients’ immune response to inflammation caused by plaque and
bacteria by removal of these disease causing agents. Professional periodontal therapy of supra and subgingival scaling, root planning,
polishing, sulcular lavage, and advanced periodontal treatments should always be performed under general anesthesia. The following
are examples of advanced periodontal disease that require further treatments.
Gingival hyperplasia
Benign gingival enlargement/overgrowth that create “pseudopockets” with increased plaque and calculus accumulation leading to
periodontal disease.
Gingivectomy/gingivoplasty
Treatment of choice for gingival hyperplasia. To re-contour the gingival margin to a normal sulcus depth the pocket is measured and
then the tissue is marked with a needle or bleeding point forceps, 3 mm coronal to the base of the pocket at several locations around
the tooth. A 45 degree beveled incision is used to excise the tissue and create a natural contour to the gingival margin. This can be
performed with #11, #15 scalpel blades, coarse diamond burs, orban knives, laser and radiosurgery. Gingival hemorrhage can be
significant but generally stops on its own within a few minutes with digital pressure applied to the area.
Periodontal pockets
Pockets less than 5mm can generally be cleaned with closed root planning. This is performed with an ultrasonic scaler as well as a
dental curette in a cross-hatch pattern to leave the root surface smooth. Additionally a placement of a perioceutic to further treat the
infected area due to their antibiotic and anticollegenase activity.
Pockets greater than 5mm require visualization of the root for adequate cleaning.
Open root planing
A full flap or an envelope flap incision is made with a #11, #15, or #15c scalpel blade, the gingival is carefully reflected with a sharp
periosteal elevator and handled as gently as possible. The root surface and pocket are cleaned with a curette in a cross-hatch pattern
with an effort to remove diseased plaque and calculus but not healthy cementum. Cementum is what attaches the tooth to the
periodontal ligament. An ultrasonic scaler with a periodontal specific tip can be used to clean and debride the pocket and root.
Ultrasonics provide water lavage, cavitation that disrupts bacterial cell walls, minimal gingival trauma, and are more efficient at
cleaning the root. A coarse diamond bur is used to smooth any bony edges of the alveolar bone (alveoplasty). Root conditioning is
then performed using citric acid to remove the smear layer and expose the dentinal tubules. Care must be taken to avoid contact of
citric acid with the gingival tissues as this may can have a necrotizing effect. The gingival is then repositioned and sutured with a 4-0
to 6-0 quick dissolving suture material such as polyglecaprone.
Regenerative osseous surgery
Alveolar bone loss is non-regenerative and will not rebuild without help. The goals of regenerative surgery are to reduce the
progression of the periodontal lesion and encourage healthy periodontal attachment. Alveolar bone loss can be vertical or horizontal
and further defined by the number of bony walls of the defect. Radiography and periodontal probing are the diagnostic tools for
evaluation of bone loss. Three and four walled pockets are excellent candidates for guided tissue regeneration whereas 2 walled
pockets have a good to guarded outcome. Those with 50% or greater bone loss should be extracted. The bone graft particulate is
placed into the bony defect after thorough open root planning to remove all disease elements. There is biosynthetic glass particulate
material or biologic allografts and autographs that can be used in the bony defects. Placement of a resorbable barrier membrane is
recommended to allow the alveolar bone and periodontal ligament to regenerate first. Without a barrier membrane the quick growing
gingival tissues will infiltrate the area first and not allow the periodontal ligament to regenerate. The defect is then closed without
tension. Bone graft material can also be used in the alveolus from large extraction sites to provide a matrix for bone healing. The
extraction site must be cleaned of all infectious debris and tissue for the graft to adhere. Meticulous homecare of brushing and oral
antibacterial rinse should be started within 5 days. Follow up radiographs and periodontal evaluation should be performed 4-6
months later.
708
Endodontic disease
Endodontic therapy involves treating the pulp of the tooth. The pulp can be described as the living part of the tooth with blood, nerve
and lymphatic components. When the tooth suffers a traumatic event the pulp can be exposed to pain, inflammation, and infection.
Restorative therapy
For teeth that have an uncomplicated crown or enamel only fractures (FX/UCCF) (FX/EF) or teeth with enamel hypoplasia placement
of a composite bonded sealant restoration can be utilized. The fracture does not extend to the pulp of the tooth but the dentin layer is
exposed. The tooth should be evaluated radiographically to ensure there is no endodontic disease. The tooth is carefully probed and
explored to “map” the defect. The defect is then contoured and beveled with a white stone finishing bur in the high speed handpiece.
Then sanding discs varying from coarse to fine are used to smooth the defect with a water rinse in between each disc. The defect is
then dried slightly and a 40% phosphoric acid etch is applied and rinsed after the recommended time. Care is taken to not allow the
etch to come into contact with the gingival tissues. The tooth is then dried slightly until it appears chalky white. The bonding primer
is then applied with a disposable brush and light cured. Lastly the bonding sealant is applied with a disposable brush and light cured.
The sanding discs can then be used to smooth the restoration site.
Root canal therapy
Involves removal of the pulp of the tooth, disinfection of the canal with sodium hypochlorite (household bleach), shaping with various
endodontic files, filling of the canal with an inert material called gutta percha, and a composite restorative placement. For teeth that
are non-vital (NV) or have complicated crown fractures (FX/CCF). This treatment will make the tooth non-vital and will weaken the
integrity of the tooth structure, therefore a crown placement should be considered. It is necessary to repeat radiographs throughout the
procedure to determine successful treatment.
Vital pulp therapy
This procedure can be performed on a very freshly fractured tooth (within 48 hours) on a relatively young animal with a wide pulp
chamber to allow for the pulp to remain vital and apexogenesis to occur. Failure of vital pulp therapy is possible and future root canal
therapy may need to be performed. The pulp is exposed and a thin layer of lining cement (MTA) is applied to irritate the pulp. A
layer of glass ionomer is placed on top of the MTA and a final layer composite restoration is applied. The tooth should be
radiographed in 6 months to check for maturation of the apex and continual dentin formation.
Being prepared to offer clients’ additional information on advanced treatments helps them make appropriate decisions for their
pets’ care. Advanced dentistry treatments should only be recommend to those owners who are willing to invest the commitment to
maintaining their pets’ oral conditions. Although many general practitioner’s perform general dentistry it is necessary to obtain
additional training to acquire the skills needed for the above treatments. In many instances it is recommended to refer these advanced
cases to the nearest veterinary dentist as the success rate is much higher in their skilled hands.
References available upon request.
709
Say Ahhh!
Oral Examination and Charting
Candice Hoerner, CVT, VTS (Dentistry)
Big Sky Veterinary Dentistry Education
Columbia Falls, MT
The oral examination involves assessing the patient while in a conscious state as well as under general anesthesia. The oral
examination should be a systematic approach and a record of findings is then added to the patients’ medical record. The technician
can aid the veterinarian in identification of abnormalities and bring them to his/her attention and record the findings on the patients’
dentistry chart. It is common practice to develop a dentistry chart that encompasses more information than the “old” dental stickers.
When charting the patients’ mouth, several abbreviations and marks can be utilized to document pathology. A current list of
abbreviations can be found at the American College of Veterinary Dentistry website (www.AVDC.org). Your clinic may find it
necessary to develop their own key of commonly used abbreviations and refer to them as necessary.
Triadan system
Identifies each tooth with a three digit number. The first number identifies the quadrant, the second and third numbers identify the
tooth. The quadrants are identified as 1xx for right maxillary, 2xx for left maxillary, 3xx for left mandibular and 4xx for right
mandibular. The teeth are numbered from the midline and move distally. The central incisor is 01, intermediate incisor is 02, and
corner incisor is 03. An easy reference is to remember that canine teeth are always 04 and the first molars are always 09 (the rule of
4’s and 9’s). Deciduous teeth are identified as 5xx for right maxillary, 6xx for left maxillary, 7xx for left mandibular, and 8xx for
right mandibular.
Directional terminology
Terms used to describe areas related to location, direction and position within the mouth
•
Medial=towards the midline of the face
•
Mesial=toward the central incisor
•
Rostral=towards the front
•
Caudal=towards the back
•
Distal=away from the midline of the face
•
Vestibular= toward the vestibule or lips (labial or buccal)
•
Labial=toward the lips (used for incisors/canines)
•
Buccal=toward the cheeks (used for premolars/molars)
•
Facial=surfaces of rostral teeth visible from the front
•
Lingual=toward the tongue (used in the mandible)
•
Palatal=toward the palate (used in the maxilla)
•
Coronal=toward the crown of the tooth
•
Apical=towards the root apex
•
Contact/Occlusal/Proximal=toward adjoining teeth in same jaw
•
Interproximal=between two teeth
•
Cusp=point of a tooth
•
Cervical/Neck= area of the tooth where the crown and root meet
Conscious oral examination
Evaluate the face, zygomatic arch, TMJ, salivary glands and lymph nodes. Identify any asymmetry or abnormalities
Oral exam- check occlusion, mucous membranes, teeth number and periodontium. Identify malodor, tooth abnormalities, and
possible periodontal inflammation
Occlusion
Normal occlusion in dogs and cats is a scissors bite where the teeth are evenly spaced and in alignment. The mouth is closed and
evaluated for the following criteria. The cusp of the mandibular incisors rest on the cingulum on the palatal side of the maxillary
incisors. The mandibular canines fit midway in the diastema between the maxillary third incisors and the maxillary canines. The
premolars create a “pinking shear” interdigitation and the mandibular first molars sit palatally to the maxillary fourth premolar. Any
deviation from this is a malocclusion and is categorized as follows:
Class 1 malocclusion
Neutrocclusion; normal relationship between the maxilla and mandible but 1 or more individual teeth are out of alignment
•
Rostral Crossbite- maxillary incisors are displaced palatally and/or the mandibular incisors are displaced labially
710
•
•
•
Base Narrow Canine-lingually displaced mandibular canine- canine may come into contact with the palate
Base Wide Canine- mandibular canine may “flare” may be attributed to lance teeth
Lance Teeth- mesioversion or retroversion of the maxillary canine tooth, closes the diastema between the maxillary
third incisors and the maxillary canine tooth
Class 2 malocclusion
Mandible is shorter than the maxilla “overbite”, mandibular brachygnathism
Class 3 malocclusion
Maxilla is shorter than the mandible, or mandible that is longer than normal, brachycephalic breeds commonly have class 3
malocclusion
Oral Examination under general anesthesia
Oropharynx-should be examined after anesthetic induction and before intubation; soft palate, tonsils, fauces, palatoglossal arch
•
Soft Tissue Exam- after completion of intubation; oral mucosa, gingiva, papillae, hard palate, floor of mouth and tongue
• Teeth- primary/permanent dentition, tooth count-to identify missing or supernumerary teeth, wear patterns, abnormal
size/shape/position, pathology (fractures, resorption)
Periodontal exam
A thorough, systematic examination of the periodontium and tooth structure to evaluate for periodontal disease. The following criteria
should be evaluated for each tooth:
•
plaque index (PI 0-3) - measurement of plaque on the surface of each tooth, PI0= no plaque, PI1 =plaque that covers
less than 1/3 of the surface, PI2= plaque that covers 1/3 to 2/3 of the surface, PI3= plaque that covers more than 2/3 of
the surface
•
calculus index (CI 0-3) – measurement of calculus on the tooth surface, CI0= no calculus, CI1= calculus that covers less
than 1/3 of the surface, CI2= calculus that covers 1/3 to 2/3 of the surface, CI3= calculus that covers more than 2/3 of
the surface
•
gingivitis index (GI 0-3)- visual and periodontal probing evaluation to identify inflammation and bleeding, GI0=no
inflammation, GI1=inflammation but no bleeding, GI2= moderated inflammation and bleeding upon probing, GI3=
severe inflammation and spontaneous bleeding
•
periodontal probing (PP)- evaluation of periodontal pocket formation with a periodontal probe “walked” around the
tooth in atleast 6 places along the junctional epithelium. Normal gingival sulcus depth in dogs=0-3 mm, cats-0.5-1mm,
consider the size of the patient you are evaluating, a great dane may have a normal gingival sulcus probing depth of 5
mm whereas a yorkie with a 5 mm probing depth would have periodontal disease.
•
gingival recession (GR)-measured (in mm) from the cement-enamel junction to the free gingival margin.
•
tooth mobility (M1-3) –assessment of how much a tooth moves from its axis using a suitable instrument such as a
periodontal probe. M0=no mobility, M1=horizontal movement of 1 mm or less, M2=horizontal movement of more than
1mm, M3= vertical as well as horizontal movement of more than 1 mm
•
furcation exposure (F1-3) -furcation exposure occurs when the bone between the roots of multi-rooted teeth is
destroyed. Using a periodontal probe the furcation is examined. In a healthy mouth the furcation is not visible.
FE1=furcation can be felt but the probe extends less than halfway under the crown, F2=probe can be passed more than
halfway under the crown but not through and through, F3=probe passes completely under the crown from buccal to
palatal/lingual
•
Wear- 2 different types that occur from repeated friction on the teeth damaging the enamel and dentin.
o Attrition (AT): occurs as a result of tooth to tooth contact often due to a malocclusion
o Abrasion (AB): occurs as a result of external objects; tennis balls, cage biters etc
•
Missing, malposition, malformed teeth –missing teeth are noted on the dental chart by circling the affected tooth/crown.
A retained tooth root (RTR) may be present radiographcally in the absence of a crown. Supernumerary (SN) “extra”
teeth or roots that are common and can be illustrated on the chart where they may be located. Malpositioned teeth can
be crowded (CWD) to close to one another or rotated (ROT) and can be drawn in on the dental chart.
•
Tooth Trauma- injury to the tooth resulting in fracture, luxation, avulsion, pulpal hemorrhage
o Tooth fracture (T/FX/fracture type)- classified by the degree of fracture
o Enamel fracture (EF)-enamel is the only involved component
o Uncomplicated Crown Fracture (UCCF) –crown fracture that does not involve the pulp
o Complicated Crown Fracture (CCF)- crown fracture that involves the pulp
o Uncomplicated Crown Root Fracture (UCRF)- crown and root fracture that does not involve the pulp
o Complicated Crown Root Fracture (CCRF)- crown and root fracture that involves the pulp
o Root Fracture (RF)- fracture involving the root
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Pulpal hemorrhage (NV)-when bleeding has occurred in the pulp canal causing increased pressure on the
nerves and blood supply usually resulting in tooth death. Causes discoloration of the tooth from purple or
tan/brown
o Luxation (T/LUX)- partial displacement of the tooth from the alveolus, tooth may still remain vital if
immediately replaced and splinted.
o Avulsion (T/A)- complete displacement of the tooth from the alveolus
•
Retained deciduous teeth (RD)- retained deciduous teeth are drawn in on the dental chart. They can cause occlusion
problems as well as increased incidence of periodontal disease.
•
Oral Masses (OM)- can be drawn in on the dental chart
•
Gingival Hyperplasia (GH)- a proliferation of gingival cells resulting in hyperplastic tissue. Can result in “pseudopocket” and periodontal disease. Common in some breeds, boxers, cocker spaniels
•
Enamel hypoplasia (EH)- loss of enamel on the tooth surface, can be localized to one tooth or generalized
•
Oro-Nasal Fistula (ONF)- open tract between the oral and nasal cavity
•
Tooth resorption (TR)- loss of tooth mineral structure, explorer tip will “snag” on defect in the tooth. Classified into 5
stages:
o TR1-mild dental hard tissue loss
o TR2-moderate dental hard tissue loss
o TR3-deep dental hard tissue loss-extends to the pulp chamber, most of the tooth remains intact
o TR4-Extensive hard tissue loss; most of the tooth has lost its integrity

TR4a-crown and root equally affected

TR4b-crown more affected than root

TR4c-root more affected than crown
o TR5-crown no longer visible; remodeling of hard tissue on radiograph
There are also abbreviations to use once the tooth has been treated.
•
Extractions: (X)- simple closed extraction
o (XS)-extraction with tooth sectioning
o (XSS)- surgical extaction
•
Crown Amputation (CRA)- amputation of the crown where type 2 root resorption is present
•
Root Canal Therapy (RCT)
•
Vital Pulp Therapy (VP)
•
Root Planing- (RPO)-Root planning open
o (RPC)-Root planning closed
•
Perioceutic- (PCT)
•
Biopsy- (B/I)-biopsy incisional
o (B/E)-biopsy excisional
As this is but a few of the commonly seen oral pathological occurrences and treatments, I encourage each individual to continue to
advance their learning by reading additional dentistry texts and visiting the AVDC website for further information.
o
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Feisty Felines:
Bringing Up the Behaviorally Challenging Kitten
Gary Landsberg, DVM, BSc, DACVB, DECVB-CA
North Toronto Veterinary Behaviour Specialty Clinic
Thornhill, Canada
Veterinarians and staff should work as a team to introduce cat owners to the concepts of normal feline behavior, reward training, and
establishing healthy social relationships. This can be complemented by handouts and a list of reading and DVD recommendations. In
addition, the clinic website should be populated with links to guide owners to the sites you recommend. Cat owners given educational
material are at reduced risk for relinquishment.1
Behavior problems in cats
In a study of 1177 cats 55% of owners reported at least one problem they would want to improve with anxiety most common at 16.7%
followed by scratching 16%, feeding problems 11%, aggression 11%, inappropriate urination and spraying 8%, and defecation in the
home at 5.1%.2 In a recent study of 277 cats, 61% engaged in one of 6 behavior problems with aggression to owners at 36%, urine
soiling 24%, intercat aggression 21%, aggression to visitors 14%, stool soiling 13% and aggression to outdoor cats,12%. Yet only
54% of owners reported these signs to their veterinarian and only about 25% of veterinarians ask.3,4 In a survey of over 1200 cats
adopted from shelters, scratching, digging and chewing were reported in 25% of cases in the first week which increased to 28% after
one month. Energy level increased (14% to 28%) as did biting and growling. Only shy, fearful and hiding reduced.5 Therefore
behavior counseling of new cat owners is essential for problems to be improved and reduced.
Feline behavior and development
Cats might be categorized as a) sociable, confident, and easy going or b) timid, nervous and aggressive. While genetics, especially
paternal, has a strong influence this is modified by environment especially prenatal (including the health, nutrition and environment of
the mother) and the early postnatal (including maternal effect, handling and socialization).6,7 Kittens separated from their mother and
hand raised by 2 weeks of age are more fearful and aggressive toward people and cats, more sensitive to novel stimuli, learn more
slowly, and develop poor social skills. Kittens receiving early gentle handling by humans develop healthier social relationships, have
accelerated development and are less fearful.
Preventive counselling
Educating new kitten owners on normal behavior, cat communication and body language, socialization, reward based training and
enrichment can help to prevent undesirable behaviors. When introducing a new cat the use of pheromones (Feliway) might lessen the
stress (improve appetite, less marking). The new cat should be given its own safe, enriched housing area, and introduced gradually to
other pets and the rest of the home while insuring positive outcomes. Feliway muli-cat might be more appropriate for multi-cat homes.
In a recent study a significantly higher percentage of owners that received no counseling sought advice (46% vs. 4%) or reported
behavior issues 10 months later compared to those that had counseling visit of 25 minutes with a veterinary behaviorist at 2-4 months
of age. Control cats had more vocalization and climbing problems (furniture, curtains), were more noise sensitive and more likely to
solicit attention when the owner was resting. Cats in the treatment group were more likely to greet on homecoming and less likely to
react negatively to body handling.8
Socialization and encouraging positive outcomes
Since the upper end of the sensitive period is 7 to 9 weeks, every effort should be made to socialize prior to this age. Treats and toys
can be used to make social interactions, handling and stimulus exposure positive. Learning should be reward based to increase
behaviors that are desirable. Clicker training can be particularly useful for immediate timing of rewards. Punishment should be
avoided as it leads to fear and avoidance.
Environmental enrichment
All animals require an environment that is physically and mentally stimulating and that meets their behavioral needs. Animals kept in
a restricted environment may not have adequate opportunity to engage in their full behavior repertoire. The indoor feline environment
should therefore provide for food, water, elimination (litter), scratching, elevated perches, comfort and security and opportunities for
enrichment including social and object play, exploration and reward training. When sufficient outlets are not available, the pet may
engage in behaviors that are undesirable to the owners or develop stress induced health and behavior issues. Many common behavior
concerns including scratching, over-exuberant play, chasing, climbing, attention seeking, nocturnal behavior, soiling and vocalization,
can be prevented, managed, or resolved by providing appropriate outlets.
•
Social time with owners and other cats plays an important role in enrichment and in maintaining healthy social
relationships. Prey type toys attached to a wand or rope can be dangled and moved to stimulate hunting which might
normally occur as many as 40 times or more a day.
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•
Reward train what you want the kitten to learn. When giving toys, treats or catnip reward and train what is desirable
and associate words to cue the interactions (communicate).
•
Feeding toys and object play: In nature cats hunt, capture, and kill multiple prey a day. As an alternative to hunting, cat
owners can offer multiple small meals in toys that require rolling, batting, chasing, pawing or chewing to release food.
Food can also be scattered or hidden to encourage exploration.
•
Outlets for scratching, climbing and perching should also be provided.
•
Outdoor access: While outdoor access may be undesirable or impractical for some homes, training the cat to be
comfortable on a leash and harness or the use of cat proof enclosures can provide a practical and safe option for outdoor
enrichment.
Elimination
Since cats generally prefer to eliminate in a substrate in which they can scratch and dig, an indoor box with commercial litter is
usually effective. Litter type, number, size, type and location of boxes, and adequated cleaning are needed to establish regular litter
box use.
Management and safety
Strategies may also be needed to prevent access to areas where problems might arise by cat proofing, blocking off areas or
confinement training. The use if an unpleasant substrate such as an aluminum pan with water, sticky tape or carpet runner with nubs
can be used to deter use of areas. .
Comfort and privacy
Cats should be provided with opportunities to perch, rest, sleep and hide, and sufficient space to be able to allow them make choices
when and where they want privacy. A normal feline time budget might allocate 44% to sleep, 22% rest and 15% grooming.9.
Neutering
Androgen influenced behaviors can be reduced or eliminated by neutering.
Kitten kindergarten
Kitten classes are valuable for socializing kittens, exposing them to a variety of novel stimuli, and teaching good manners. Offering
these classes in a veterinary clinic help the kittens (and owners) develop positive associations with the veterinary clinic and staff.
Topics include positive body handling, reward training, litter box management, enrichment, adminstering medication, handling,
harness and crate training, the perils of punishment, and sessions to socialize and play.
The feisty feline
Scratching
Scratching serves a variety of purposes including marking, nail maintenance, and stretching after rest and may increase in response to
stress. Owners should provide a scratching post at or near the cats preferred scratching location with a substrate and structure that is
appealing, ideally one that is similar to what the cat is presently targeting. Placing catnip, or treats in the area, rewarding / clicker
training and the use of feline interdigial pheromone (available in Europe) will encourage the use of the post. In a recent study of over
4000 cats, cats that were rewarded were more likely to use the preferred post and punishment did not affect frequency of inappropriate
scratching.10 While carpet was the most frequently offered substrate, rope (sisal) was used most often (33%) followed by carpet
(25%) and cardboard (18%). Cats over 10 preferred carpet (25%), rope (23%) and cardboard (20%).10 Most cats 9 or less preferred
cat trees with multiple levels (76%) followed by vertical posts (69%), horizontal (50%) and hung on the wall 6%). Cats preferred
posts that were narrower < 3 feet, and shorter <3 feet.10
Inappropriate scratching was reported by 52% of owners, 65% at least once a day and 35% multiple times daily and was unrelated
to number of cats or sexual status. Cats obtained from breeders had least inappropriate scratching (38%) and those from shelters most
(54%). Inappropriate scratching was associated least with rope covered posts. Cat trees with two or more levels were associated with
least inappropriate scratching (55%) with those hung on the door associated with most inappropriate scratching (74%). Inappropriate
scratching was less with posts >3 feet (55%) compared to smaller posts (65%). Of cats that were declawed 8.5% were in the front and
.9% front and rear, primarily to prevent damage (44%), followed by injury to people (18%) and injury to other pets (11%). Twenty
nine percent of cat were declawed when obtained.10
Cats that continue to scratch inappropriate targets in response to stress might benefit from applying Feliway to these areas. To
prevent further scratching at a site, the scratching post might be placed directly in front of the area, access to the area can be blocked,
the cat confined away from the site, or environmental deterrents used. Outdoor access may reduce indoor scratching but there is no
evidence that it improves inappropriate scratching.10
Play / predation
When aggressive play is directed at the owner, the primary focus should be to redirect the predatory play to appropriate outlets such as
toys attached to ropes or wands or that can be tossed to stimulate chasing, pouncing and biting at times of day when the behaviors are
most likely to arise. When hunting, cats engage in multiple short bouts of chase, may have a daily catch of 8-10 mice, with excursions
lasting up to 30 minutes.11 A cat may spend 14% of its day hunting, 3% traveling and 2% feeding.9 Therefore it is not surprising that
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some cats, will engage in multiple stalk, chase and bite sessions toward owners and other cats. However, perhaps surprisingly in one
study cats that hunted and those that spent more time outdoors were reported to have more behavior problems.3
Play with toys can provide an alternative outlet for hunting behavior as well as an opportunity for social interaction and training.
Toys with play like characteristics (size, movement, odor) will solicit play.11 However after two to three bouts of chase with a
specfic toy, the cat may lose interest but remain in a heightened state of arousal. Within 5 minutes play with a novel toy was
disinhbitied and more intense with 25 to 45 minutes needed till intensity is reduced.11 Therefore at least one or two additional toys
should be offered for novelty, and the cat offered an alternative activity such as a food filled or catnip toy or a small meal to keep it
focused, allow the cat to settle and perhaps simulate prey capture. In one study owners that played with their cat in more than 5 minute
bouts a day had fewer problems.3 Owners should diarize when play attacks arise so that they might schedule pre-emptive play or
confine the cat with alternative forms of enrichment (e.g. food filled toys, cardboard box to explore).
Since satiation reduces the motivation to hunt and play, feeding multiple small meals might also reduce play predation.12 Training
the cat to engage in desirable behaviors on cue (e.g. sit, go to your mat) provides the owners with a communication tool to direct the
cat into alternative acceptable behaviors if the owners can identify the body language of impending attack. If signs and situations for
aggression are recognized the owner can throw treats to redirect and countercondition the cat. Leaving a bell attached or a leash and
harness to inhibit and redirect the cat might also be helpful. While getting a second “compatable” cat could result in new issues, it can
be an effective solution for some cases.
Social relationships
When adopting a new cat, it should be confined to its own enriched housing area within the home, so that it might be gradually
introduced to other cats, people and increasingly more of the home while insuring positive outcomes. Over time, some cats develop
strong bonds with other cats, while some require very gradual introduction and an ongoing need for space, privacy and restricted
interactions.
Petting aggression
This aggression may be inhibited or intense. What is most confusing to some owners is that the sequence may begin with the cat
seeking physical contact. However, after a variable period of time, the cat may become agitated and bite. This may be related to the
cat’s level of arousal, previous unpleasant experiences with handling and restraint or even a sensitivity to touch. Owners must learn to
recognize feline body language to identify the earliest signs of anxiety, as well as when and where problems might arise and the type
and length of petting the cat will tolerate. While recognizing and respecting the cats limits, giving rewards during petting and ceasing
before any signs of anxiety can gradually countercondition a longer response.
Summary
Understanding normal feline behavior and development is necessary to adequately meet the kittens needs Many of the most common
undesirable behaviors in cats can be effectively addressed by understanding and meeting these needs. Preventive counseling is
effective in preventing many of the common feline undesirable behaviors. Therefore, veterinarians and staff should be proactive in
providing behavior advice and resources for client education
Web resources
Ohio State University: environmental enrichment
www.indoorpet.osu.edu, https://indoorpet.osu.edu/sites/indoorpet/files/assets/documents/KeepingCatsIndoors-2013.pdf
American Veterinary Society of Animal Behavior: www.catvets.com
International Society of Feline Medicine: www.icatcare.org
Catalyst Council: catalystcouncil.org
AAFP and ISFM feline environmental needs guidelines: http://bit.ly/14uWTCB.
References / suggested reading
Patronek GJ, Glickman LT, Beck AM et al Risk factors for relinquishment of cats to an animal shelter. J Am Vet Med Assoc 1996; 209; 572–581
Heidenberger E. Housing conditionis and behavioral problems of indoor cats as assessed by their owners. Appl Anim Behav Sci 1997; 52: 345-364.
Strickler BL, Shull EA. An owner survey of toys, activity problems and behavior problems in indoor cats. J Vet Behav 2014; 9, 207-214
Hetts S, Heinke ML, Estep DQ. Behavior wellness concepts for general practice. J Am Vet Med Assoc 2004, 225, 506-513
Lord LK, Reider L, Herron ME, et al. Health and behavior problems in dogs and cats one week and one month after adoption from animal shelters. J
Am Vet Med Assoc 2008; 233, 1715-1722
Lowe SE, Bradshaw JW. Ontogeny of individuality in the domestic cat in the home environment. Anim Behav 2001; 61; 231
McCune S. The impact of paternity and early socialisation on the development of cats’ behaviour to people and novel objects. Appl Anim Behav Sci
1995; 45; 109
Gazzano A, Bianchi L, Sonia C et al. The prevention of undesirable behavior in cats; effectiveness of veterinary behaviorists’ advice given to kitten
owners. J Vet Behav 2015; in press, DOI: 10.1016/j.jveb.2015.07.042
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Panaman R. Behavior and ecology of free-ranging female farm cats. Z Tierpschol 1981; 56; 59-73
10. Wilson C, Bain M, DePorter T, et al. Owner observations regarding cat scratching behavior: an internet-based survey. J Fel Med Surg 2015; in
press, DOI: 10.1177/1098612X15594414
11. Hall SL, Bradshaw JWS, Robinson IH. Object play in adult domestic cats: the roles of habituation and disinhibition. Appl Anim Behav Sci, 2002;
79; 263-271
12. Hall SL, Bradshaw JWS. The influence of hunger on object play by adult domestic cats. Appl Anim Behav Sci 1998; 58; 143-150
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Take Dentistry Beyond Prophies
Matt Lemmons, DVM, DAVDC
MedVet Indianapolis
Carmel, IN
Dentistry is a key part of small animal practice and the veterinary technician is one of the most valuable assets to success in dentistry.
A well trained technician not only aids in the procedural portion of dentistry, but also can help educate clients. The roles of the
veterinary technician in small animal dentistry are part dental hygienist, part dental and surgical assistant, part maintenance and part
client education.
Rules for dental success and happiness
Quit doing ‘dentals’.
The word dental is an adjective used to describe a non such as a dental scaler or dental radiograph. It is not a medical procedure.
Often we tell a client we need to ‘do a dental’ on their pet. This does not describe what we are going to do. We are going to perform
an anesthetized dental cleaning and polishing and perform a complete oral health evaluation and treatment. This sounds more
professional and conveys the value of the procedure to the client.
Protect your health!
Performing dental cleanings can be hazardous to our health if we do not take certain precautions. We should always wear a mask,
googles (not glasses) and gloves. We should also be aware of our posture. Ideally your back should be straight, elbows naturally at
their side and hips slightly tilted as how we naturally stand. Slouching or pulling the elbows up can cause headaches, neck and back
aches and fatigue.
Leave the extractions to the veterinarian.
There are numerous serious complications that can occur while performing extractions. If this were to happen, veterinarians carry
malpractice insurance. If extractions are illegal for technicians to perform in your state, you may be financially responsible for
complications.
Get involved and get excited!
Ask your doctor questions about the procedure. Volunteer to teach tooth brushing techniques to the clients. Client education on home
plaque prevention is a cornerstone of periodontal disease maintenance and prevention.
Role as a dental hygienist
In a dental practice for people, the dental hygienist is charged with performing the dental cleaning including making dental
radiographs, scaling and polishing and observing for signs of oral disease. The veterinary technician often is responsible for the same.
In efficient dental practices, technicians can make full mouth dental radiographs for the doctor to evaluate while the teeth are being
cleaned. Making dental radiographs does take practice to master but are not difficult. In our practice, all pre-operative radiographs
are made with the patient in dorsal and sternal recumbency. With dental radiography this process is very efficient.
Dental scaling is the process of using either hand instruments or powered equipment to remove dental calculus from the tooth.
These instruments convert electrical energy into mechanical energy to aid in removal of calculus from the tooth. A light touch is
required to be efficient with ultrasonic scalers. These instruments should only be held to a tooth for a few seconds at a time or
excessive heat is generated and may lead to pulp necrosis. Additionally, the tip of the instrument should not be angled toward the
tooth as it has a jack hammer action and may lead to iatrogenic damage. Two classes exist; magnetostrictive and piezoelectric.
Magnetostrictive units have either a ferrite rod which is active along the distal 12mm of the tip or a ferromagnetic stack which is
active along the distal 4mm. Piezoelectric scalers are active along the distal 3mm. The basic maintenance of these instruments
depends on the type. Ferromagnetic stack units have a stack magnetic leaves welded at one end which flex and bend to cause
movement. With time these leaves begin to separate, reducing the efficiency of the instrument and thus require replacement. Ferrite
rods do not necessarily wear out, but if dropped may break and then need to be replaced. The tips of the Ferrite rod units and
piezoelectric units eventually wear away and once worn past their working end, need to be replaced. If used subgingivally, smaller
inserts are available and the power to the unit should be reduced. Inserts are available for highspeed handpieces which will remove
calculus. However these inserts also damage the tooth and hence were banned by the American Dental Association.
The recommended pattern for cleaning teeth is an overlapping serpentine motion starting near the gingiva and ending at the cusp.
The presenter performs dental cleanings with the patient in dorsal recumbency and the oropharynx protected with a gauze pack. This
position allows the technician to see all surfaces of the teeth. A dental mirror may be needed to visualize the distal surface of the
molars.
In addition to ultrasonic scaling, hand scaling and use of hand curettes is needed. Hand scaling is used to remove persistent
calculus after ultrasonic scaling and to clean developmental grooves in the teeth. Hand curettes are used to clean periodontal pockets
below the free gingival margin. These instruments have a rounded toe at the working end versus a point as in a scaler. The rounded
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end reduces the risk of macerating the gingiva when the instrument is placed into a sulcus or pocket. There are several shapes and
sizes of curettes and scalers available. Area specific scalers and curettes have an acute angle between the face of the instrument and
the terminal shank. These instruments are extremely useful for cleaning interproximal pockets. As with all bladed instruments,
scalers and curettes only work well when kept sharp.
When the teeth are presumed to be cleaned, it is recommended to use the three way air water syringe to dry the surface of each
tooth and to gently blow open the gingiva to visualize the whole crown. If tartar remains, it will be more obvious when dried.
Alternatively disclosing solution can be used to better visualize the remaining tartar.
After all surfaces of the teeth are scaled, the teeth should be polished to remove small calculus or tartar deposits not removed
during scaling and to smooth any scratches in the enamel caused by scaling. This is performed with a low speed handpiece, a trophy
cup and either prophy paste or pumice. When polishing there should always be paste or pumice in the prophy cup since these and not
the cup actually polish and enough pressure should be used to slightly flare the cup. Fluoride is often used as a final preventive
product. Fluoride may help remineralize the teeth and has bacteriostatic properties which may aid in deceasing the incidence of
periodontal disease. Commonly foam is used which is left in contact for 1-3 minutes and wiped (not rinsed) away.
Role as dental and surgical assistant
Four handed dentistry describes the teamwork between the dentist and assistant to efficiently examine and chart dental pathology and
perform dental procedures and surgery. This works for the veterinarian and technician as well.
The first part of this is four handed dental charting. This is performed by the veterinarian naming of pathology noted on each
tooth, quadrant by quadrant and the technician making note in the dental chart. In our practice we examine the right maxillary
quadrant, then right mandibular, then left maxillary and finally left mandibular. The modified triadan system works very well for this.
The modified triadan system is a numbered system based off the quadrant (left or right maxillary or mandibular) and the type of tooth.
The first number qualifies the quadrant and is 100, 200, 300 or 400. The right maxillary is the “100” quadrant, left maxillary the
“200” quadrant, left mandibular the “300” quadrant and right mandibular the “400” quadrant. If facing the animal, these numbers
increase by 100 in a clockwise fashion. The first incisor is -01, second -02 and third -03. Thus the right maxillary first incisor is tooth
101, the left maxillary first incisor is 201, left maxillary second incisor is 202. The canine teeth are -04. The premolars begin at -05
and end at -08. Because the cat does not have a maxillary first or mandibular first or second premolar, the maxillary -05 and
mandibular -05 and -06 are not used for cats. The molars start at -09 and proceed to -10 in the maxillae for dogs and -11 for the
mandibles in dogs. Cats only have the -09. A hint to quickly remember which tooth is which is the canine teeth are always -04 and
the fourth premolar is always -08 and first molar always -09. For example the left mandibular fourth premolar is tooth 208 and the
adjacent molar is 209. The right maxillary canine is 104 and right mandibular canine is 404.
It also is easier to learn and use the abbreviations developed by the American Veterinary Dental College. These can be found at
http://avdc.org/abbreviations.doc. In addition to examining each tooth and the associated gingiva, the tongue, palate, cheeks and
tonsils should be examined.
Four handed dentistry does not stop at only recording findings. The trained technician is also a key part in making dental
procedures and surgery proficient. During surgery the technician assists in retracting, hemostasis and assisting during suturing. When
performing more advanced procedures such as root canal therapy, the technician aids in preparing instruments and materials, thus
saving valuable time.
Maintenance
All edged instruments must be kept sharp in order to work properly. Hand instruments may be sharpened on a flat stone or with a
mechanical sharpener such as the Rx Honing machine. When sharpening hand scalers and curettes, the face of the blade is kept at a
110 degree angle to the stone and the curved portion of the instrument is placed against the stone. Sharpness can be checked with an
acrylic stick.
Luxators and elevators are sharpened on the back of the blade The face of the blade is held at a 70 degree angle to the stone and
pushed back and forth until sharp.
Air driven equipment includes the highspeed hand piece and low speed hand piece are generally operated by a air compressor. The
compressor itself must be maintained so the motor does not seize. Typically the oil within the compressor must be changed yearly and
maintained at a certain level. Only distilled water should be used in the irrigant bottle. Impurities in tap water can accumulate and
harm the machinery. It is also beneficial to add a cleaning tablet to the distilled water to prevent waterline contamination. These are
generally colloidal silver and can be found through several distributors.
Before each use, the high speed handpiece and low speed handpiece should be oiled with a handpiece lubricant. The high speed
unit uses friction grip carbide burs used to remove bone are either round burs or pear shaped burs and to cut the tooth, a cross cut type
bur such as a 700 series is used. Carbide burs have a finite life and should generally be disposed of after 3-5 uses. When looking for
replacement burs, make sure the initials FG are on the package, not HP or RA.
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Role as educator
The most important role of the technician in veterinary dentistry may be that as educator for the clients. This can start as early as the
first few puppy/kitten visits with the new patient. Early on the technician can discuss normal eruption times and exfoliation of
deciduous teeth of the puppy/kitten and what it is important that retained deciduous teeth be promptly treated. The normal eruption
times are as follows
Dog deciduous
•
Incisors 3-4W
•
Canines 3W
•
Premolars 4-12W
Dog permanent
•
Incisors 3-5M
•
Canines 4-6M
•
Premolars 4-6M
•
Molars 5-7M
Cat deciduous
•
Incisors 2-3W
•
Canines 3-4W
•
Premolars 3-6W
•
Cat Permanent
•
Incisors 3-4M
•
Canines 4-5M
•
Premolars 4-6W
•
Molars 4-5W
It is also a great time to discuss proper chew toys for the puppy and kitten. The client should be aware that there are several chews
that can be destructive to the teeth. Items such as antlers, bones and hard plastic toys easily break teeth.
Begin discuss tooth brushing and dental treats after the adult teeth have erupted. Daily tooth brushing is the most effective, but
every other day is still effective. Recommend dental products with the VOHC seal. These can be found at vohc.org
Further training
Veterinary technicians can become certified by the Academy of Veterinary Dental Technicians. This process entails keeping a case
log to show experience with many types of dental cases, writing case reports and passing a written and practical examination. It does
not give license to perform additional procedures, but shows proficiency in the procedures performed by the technician.
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A Painless Career Choice:
Careers for Technicians in Pain Management
Tasha McNernery, BS, CVT, CVPP
Veterinary Anesthesia Nerds
Glenside, PA
Today technicians can pursue further training and specialization in many avenues including dentistry, anesthesia, internal medicine
and emergency and critical care. The possibilities are seemingly endless for technicians who wish to further their education and
expand the depth of their career.
One such avenue for extra training and knowledge is in the field of pain management. This is an exciting new avenue for
technicians (and veterinarians as well) to help strengthen not only the practices bond with the animal but the clients relationship as
well. Pain management has become an important specialty area in human medicine and that has inevitably led to a greater awareness
of pain in animal companions. Pet parents want the best for their furry family members and that includes top-of-the-line treatments for
pain management.
It was once thought that animals did not experience pain in the same way that humans do. But research supports that if a procedure
is thought to be painful to us, it will also be painful to our fuzzy friends as well, even though they may go to great lengths to hide it
from us. Therefore proper pain management must be offered to all patients. In addition to pain medications (analgesics), many clinics
are now offering complementary treatments like physical rehabilitation, acupuncture and laser therapy to treat pet pain.
In veterinary medicine we now know that pain is best managed through an interdisciplinary approach and that effective pain
management can be best achieved through cooperation, sharing knowledge, and the collective wisdom of veterinary professionals
from many disciplines. The International Veterinary Academy of Pain Management is the cornerstone of knowledge and advancement
in the field of pet pain management. They currently execute a program for veterinary professionals to gain advancement in the field of
pain management.
The IVAPM’s current program will lead to the title of Certified Veterinary Pain Practitioner (CVPP) for veterinarians and licensed
technicians; Certified Animal Pain Practitioner (CAPP) for physical therapists and physical therapist assistants with certification in
canine rehabilitation. This is an exciting opportunity for veterinary technicians in particular. It is IVAPM’s strongly held view that the
CVPP and CAPP recognition is well within the scope of any veterinary professional to attain, and the IVAPM encourages all to
consider its merits and begin the application process.
The certification program is intended to emphasize the value of the many disciplines capable of enhancing patient comfort and
quality of life, and to facilitate an understanding of the modalities not necessarily in the technician’s current area of familiarity. These
areas include:
•
Analgesic drug therapies
•
Analgesic adjunct therapies
•
Physical rehabilitation methods
•
Complimentary alternative therapies such as acupuncture and massage
Obtaining the CVPP/CAPP provides the stage upon which all professionals committed to promoting, enhancing, and advancing
pain management in animals may interface. It is the foundation upon which the veterinary profession can build the most effective
multidisciplinary pain management team. By using a multimodal approach the CVPP can use analgesic drug therapies along with
physical therapy techniques such as massage, hydrotherapy and acupuncture to create a multidimensional pain management plan to
help the patient achieve the desired outcome
After obtaining a CVPP, the veterinary technician can work together with pet owners and veterinarians to provide the best pain
management plans for patients. CVPP’s can best be used in the following 3 ways:
1. The CVPP can assess the patient’s current status and pain management regime and together with the owner create a
pain management plan specific to that patient for the best overall outcome.
2. CVPP’s can also help in the acute pain management setting helping clinics to create protocols for post-operative pain
scoring and proper analgesic techniques for acute surgical pain.
3. The CVPP also acts as an important “point person” that the owner can contact and relay information about the pet’s
progress. The CVPP can then use this information to make changes to the analgesic plan as necessary to ensure the best
outcome for that patient.
By obtaining your CVPP you can also help in the continuing education of your clients and staff. Many veterinary professionals
who have obtained the CVPP designation go on to write magazine articles, teach online courses, and lead seminars on various pain
management topics.
There are so many opportunities for the veterinary technicians when it comes to pain management. Technicians can further their
education and become certified in acupuncture, massage therapy, reiki and various other pain management modalities.
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By reaching the goals associated with a Certified Veterinary Pain Practitioner, veterinary technicians can increase patient safety
and comfort, increase the overall morale at your practice, educate clients on the importance of proper pain management, and increase
client compliance in this area.
If you are a veterinary technician with an interest in pain management please consider the CVPP/CAPP path. If you have any
questions about this process, please visit the IVAPM website at www.IVAPM.org or 615-301-3040 by phone.
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Pain Management and Profitability:
Stop the Hurt
Tasha McNernery, BS, CVT, CVPP
Veterinary Anesthesia Nerds
Glenside, PA
There are many reasons for providing appropriate analgesia to your patients, and thankfully for the overall economic health of a clinic
pain management can also boot your practices bottom line.
Providing appropriate or even advanced analgesic techniques not only provides an economic benefit to your practice, but it also
improves overall staff morale and job satisfaction. Technicians and nurses are able to identify painful patients and if they are allowed
to play an active role in the alleviation of a patients’ pain, they have an overall greater sense of purpose at the clinic and increase in
job satisfaction. Technicians who are proud of the level of analgesia provided for acute and chronic painful patients often stay at their
place of employment longer.
Pet owners are also more educated and expect that their pets pain will be taken seriously and treated appropriately. Whether
providing an analgesic regime to treat acute post-surgical pain, or developing a chronic pain plan for a senior osteoarthritis patient,
clients have come to expect effective analgesic options. And, many clients are willing to pay appropriately so their beloved pet is not
in pain.
When looking at the cost of analgesics, any of the drugs used are relatively inexpensive. The opioid analgesic Morphine for
example is one of the cheapest yet most effective analgesic options available. It can be used as a pre-medication prior to surgery, or
for added revenue to the practice and increased pain control during surgery it can be titrated to the patient via constant rate infusion.
Offering specialized analgesic options such as constant rate infusions or anesthetic local blocks can provide additional revenue as
the clinic should charge appropriately for the supplies needed and for the expertise and additional training of veterinarians or
technicians. Technicians can be trained to administer highly effective local blocks including epidurals. An effective epidural will not
only improve patient comfort, but also cut down on the use of inhalant anesthetic during the surgical procedure as well as additional
rescue analgesics often needed during surgery. If appropriate local and nerve blocks are used during each surgical procedure and
charged a small appropriate fee, the practice will see a considerable difference when that small fee is multiplied by the potentially
hundreds of surgeries that are done each year.
Some of the simplest ways to provide increased patient comfort and increased revenue without a big investment are as follows
1. Provide regional or nerve blocks to every surgical patient
2. Start using constant rate infusions for pain relief
3. Have a member of your team be the captain of the Pain Police and send them for additional training in analgesic
options.
4. Become a member of the IVAPM. www.IVAPM.org
By implementing some simple changes and setting an appropriate in clinic point person, your practice will be known as the go to
for the best level of pain management.
Resources
Epstein, Mark; Pain Management: The Positive Effects on Your Practice and Patients. www.DVM360.com, February 2011.
McLain Madsen, L. The Economics of Pain Relief. Veterinary Economics 2007; 48(6): 30-35
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What’s Your Role?
A Team Approach to Talking to
Pet Owners about Pain Management
Tasha McNernery, BS, CVT, CVPP
Veterinary Anesthesia Nerds
Glenside, PA
Often times pet parents are faced with the decision whether or not to put their pets under general anesthesia for a surgical or dental
procedure. They are also often worried about whether or not their beloved pet will be in pain afterwards and how they will be able to
best manage this pain. Veterinary team members are often the ones responsible for explaining things to the client to alleviate some of
the fear associated with post- operative recovery and pain management. Veterinary team members should also be prepared to discuss
chronic pain conditions such as osteoarthritis.
Reception
When a client calls the clinic, the receptionist is the front line for obtaining information from the client. Receptionists can ask
questions to help get a clearer picture of the painful condition either chronic or acute. Some examples include:
1. How long has your pet been experiencing pain?
2. Does the pain appear to be localized to one area?
3. Is your pet licking or biting at a certain area of the body?
4. Has your pet stopped eating/grooming/jumping/running?
5. Does your pet take a long time to stand after sitting or sleeping?
Technicians/nurses
Taking the time to get a complete history will be the key to ensuring proper pain management. Be prepared to talk with clients about
acute pain after surgery. Orthopedic procedures and dentistries that have required multiple extractions however, may require a longer
recovery time. Also after surgery patients may be unsteady on their feet and unable to walk up or down stairs. If their pet usually
sleeps upstairs in bed, it’s important to set up a comfortable area on the first floor for their pet to rest in when they come home, or be
prepared to carry their pet up and down the stairs! Also explain to the client that some post-operative pain medications such as opioids
may make their pet nauseous and whiny; if this happens they should call the office.
Almost every surgical and dental procedure will involve some level of pain. Talk with the client about the expected level of pain and
how this pain will be treated. Also talk with the client about the need (if any) for post-operative physical therapy. Orthopedic
procedures greatly benefit from post-operative physical therapy such as hydrotherapy, massage therapy, and low level laser therapy.
Also, many pain medications have to be administered orally. If it is difficult for clients to give their dog or cat a pill, there are now
other drug delivery options to ensure pets stay comfortable in the recovery period.
Doctors
The doctors play a very important role in piecing the information together to create the best pain management action plan. By
combining patient history with a thorough physical exam a concise and effective pain management plan can be created. The most
important aspect of managing pain is to work with a multi-modal treatment protocol. The principle of multimodal therapy is to use
analgesic drugs and physical therapy modalities that target several different steps of the pain pathway, allowing more effective pain
control with fewer side effects.
NSAIDs remain the mainstay of therapy for chronically painful patients. Their principal mode of action is to block prostaglandin
production by binding and inhibiting cyclooxygenase (COX). The result of this effect is mainly a reduction in inflammation.
Opioids are useful in a variety of painful conditions (though they may have limited effectiveness in some forms of neuropathic
pain). Opioids may be particularly useful for chronic pain management, as they are available in oral and transdermal versions.
NMDA receptor antagonists are often used as adjunctive drugs (i.e. in combination with other analgesics) to improve the control
of pain. Intense and/or chronic painful stimuli result in changes in the central nervous system’s response to input, leading to an
increase of pain intensity. NMDA receptor antagonist drugs help to control and treat this “amplification”. Amantadine is the most
commonly used oral NMDA receptor antagonist. It was originally developed as an antiviral compound, and has also been used to treat
Parkinson’s disease in humans.
Gabapentin has been used for many forms of chronic pain, though its best application may be for neuropathic pain. Gabapentin is
an anti-convulsant medication with significant adjunctive anti-hyperalgesic action. Gabapentin is commonly used in conjunction with
opioids for analgesic treatment options in post- amputation patients.
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Tricyclic antidepressants (TCA’s) have been used in humans and animals as adjuncts to other analgesics (especially opioids) for
chronic pain. They act to inhibit serotonin and norepinephrine reuptake, though they may have other analgesic effects as well
(including possible actions at opioid receptors and on nerve transmission).
Non-pharmacologic therapies for chronic pain management include acupuncture, electroacupuncture and, laser therapy and pulsed
magnetic field therapy. Hydrotherapy is also a useful treatment option for patients that have IVDD or osteoarthritis. Often the best
course of treatment is to combine physical therapy with pharmacological therapies.
Kennel/support staff
Kennel staff also play an important role in recognizing patients in pain. Because patients who are boarding for long periods of time,
kennel staff may notice limping, sensitivity when an area is touched, patients that are uncomfortable and unable to rest, or a change in
body language. If the kennel staff notices signs of pain in boarding patients, they should alert the nurses or veterinarians so that the
owner can be notified and proper pain management plans can be enacted.
When all staff members work together, we can create a pleasing pain free environment for our patients. Everyone wins!
Another way you can ensure your patients are receiving the most comprehensive pain management plan is to become an IVAPM
(International Veterinary Pain Management) member.
The IVAPM is an organization that seeks to educate and promote pain management for animals worldwide. It also provides
continuing education in the area of pain recognition and treatment. IVAPM members can work toward certification in the management
of animal pain. To find a CVPP or IVAPM member in your area, visit the IVAPM website at www.IVAPM.org
References
Multimodal Pain Management in Orthopedics: Implications for Joint Arthroplasty Surgery
Javad Parvizi, MD, FRCS; Michael R. Bloomfield, Orthopedics, February 2013 - Volume 36 · Issue 2: 7-14
Gaynor, James and Muir, William. Handbook of Veterinary Pain Management, 2009, Mosby. St.Louis. MO
Thompson, Dave. Chronic Pain. www.vasg.org/chronic_pain_management.htm, Revised 2011
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Breed Positivity in Your Practice
Ori Scislowicz, BS, LVT
CVCA- Cardiac Care for Pets
Richmond, VA
A positive outlook can go a long way in your everyday life, as well as within your practice. Unfortunately, many of us have been
inundated with negativity from some of our coworkers. We have all worked with that team member who starts the day complaining
they are having a bad day and that’s why they may be exuding pessimism all day. This is a very toxic approach to the workplace as it
can spread throughout the team, creating an epidemic of unhappiness, and make everyone’s lives much more stressful, as well as their
days longer.
What IS a toxic work environment?
The enemy of positivity in the workplace is an environment of toxicity. Toxic work environments often have chronically high stress
levels, whether that be due to the work being consistently intense, or a fear-based culture. Employees may also have a poor work/life
balance, where work is eating into their personal lives and enjoyments. There may be a general lack of enthusiasm and loyalty to the
practice. The expectations by the supervisors may be unrealistic, causing team members to feel as though they are constantly failing.
Dysfunctional leaders can also create toxicity by bullying the team, poorly communicating, and/or being unwilling to help and
communicate.
The repercussions
Being part of a workplace consumed by negativity has a detrimental effect on the employees, and ultimately the success of the practice
as well. Employees often develop stress-related physical and mental illnesses such as gastrointestinal upset, anxiety, depression,
cardiovascular disease, migraines, and musculoskeletal problems. In a 20 year study, published in 2011, researchers at Tel Aviv
University found a startling connection between the relationship between the workplace and the individual’s risk of death. Fifty-three
individuals had died by the conclusion of the study in 2008. These individuals were significantly more likely to describe their work
environment as hostile compared to those who survived.
Adjusting your own perspective
Fortunately, there is a lot that is in our own power to change and promote positivity. You ultimately choose how to react to certain
circumstances. Although it’s not our natural response, taking on an excessive workload or dealing with a difficult team member/client
is much easier when approached with a positive attitude. Remember it’s never a good idea to allow other’s baggage to live rent-free in
your head.
We push through our lives with all goals meeting a larger goal of achieving happiness. Many team members see work as a
necessary evil (and hurdle) to getting closer to that goal. It’s a much healthier outlook to view work as another opportunity to strive for
inner happiness as you spend 40 plus hours a week there. Gratitude is also a great way to reframe your outlook amidst negativity at
work. Try to remind yourself of what you are thankful for on a daily basis, especially during the most stressful moments.
Posture can also play a role in your own perspective of the day. Keeping your posture upright can help improve confidence levels
and overall physical health. If you feel well-rested and energetic, you are better able to cope with difficult days.
Self-care is very important in combating negativity around you. Giving yourself time around your workday for something that you
enjoy can greatly improve your mental state. That optimistic perspective may also rub off on your less than happy teammates.
Many of us in veterinary medicine are in a field that utilizes our strengths and ignites our inner passion. Keeping the big picture in
mind and continuing to work towards a greater good can help conquer the more difficult days.
Creating an overall positive atmosphere
Outside of controlling our own responses to negativity, we can also help battle toxicity and grow a more positive practice.
Taking the approach of being energetic, charismatic, and people-oriented can help defuse the group’s stress. If an employee, or
even a client, seems stressed at the beginning of the day, try to go out of your way to help them out. Pick up extra tasks, and ask them
if they need to talk. If a team member is in a very bad mood, it may be best to take the day off. Team members should not be taking
“mental health” days regularly, but a stressed or burned-out employee may need the time once in a blue moon. You’ll find that the day
flows much better and the team is more productive (even being short-staffed) without the negative aura. If the behavior continues
regularly, then coaching by a manager needs to come into play.
Infusing positivity by allowing team members to have a place to look at a family photo, to decorate for the holidays, or even to add
plants, is wildly beneficial. Encourage the team to take breaks when they are overly stressed or emotionally overwhelmed, and go for a
short walk or listen to an uplifting song.
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Reward systems aren’t just for your pups in the clinic. Team members love to get recognition as well, and it greatly improves
morale. Whether it’s a friendly contest to book the most dentals or sell a certain product, or simply a submission box for kudos from
fellow team members, a reward system is a must. The rewards can be small too, a $5 or $10 gift card, or ordering pizza for the staff.
The benefits to the practice far outweigh the minimal cost.
Practices should also be assessed for dysfunctional relationships. Negativity often grows from clique culture, along with
insincerity, favoritism, and grudge-holding. Make it clear to new hires that this behavior is unacceptable and will not be tolerated.
With current employees, agree to set a new pattern and eliminate these behaviors. If still present over time, coach employees, and even
make them go home for the day if they continue to exhibit this unprofessional conduct.
There’s no arguing that converting toxicity into positivity is a difficult, gradual process in damaged practices. It is not impossible
though. With a strong emphasis on keeping team members satisfied and happy, the practice will see greater output and success as well.
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Bring Fast Success to Your Practice with Modern Marketing Tactics
Ori Scislowicz, BS, LVT
CVCA- Cardiac Care for Pets
Richmond, VA
Taking advantage of marketing opportunities in your veterinary practice will not only help your practice grow but also can give you a
chance for personal growth. Marketing is a great creative outlet and a nice way to switch things up in the sometimes cut and dry life of
a technician working on the floor. Thanks to our ever growing technologically advanced world, there are many new marketing outlets
available. These modern strategies allow for a quick way to expand your outreach into the community.
Inbound versus outbound
It’s helpful to understand the difference between inbound and outbound marketing strategies. Inbound is comprised of your modern
tactics, including (but not limited to) reaching out via social media, blogging, viral videos, and search engine optimized (SEO) website
text. Outbound marketing is more of the “old school” approach, also sometimes referred to as “interruption marketing”. The idea in
outbound marketing is to reach out to the largest group of people possible, but it lacks direction and can be considered aggressive.
Outbound marketing techniques include advertising (billboards, newspapers), cold calling, and direct mail. Since the advertising
business is trying to push out their message to the general public in as many ways as they can, in the hope of reaching some interested
individuals, this can be a very expensive approach.
Inbound marketing has a more sophisticated approach, connecting with potential clients through content the viewers would seek by
themselves. Originally, this approach may have only accessed younger individuals, but in today’s world, even our grandmothers are
on social media. Another advantage of this form of marketing is that a company can interact with their clientele and create a more
casual and engaging, as well as less aggressive, exchange.
Social media
When your practice decides to explore marketing options through social media, it’s important to understand your potential audience
through the various outlets. For example, Facebook users are mostly under 30 years old, with individuals educated minimally at a
college level. While Facebook is very popular with women, it has a decent male user database as well. Twitter is more balanced when
it comes to gender, but mostly consists of users in their late teens to late twenties. Twitter’s users are mostly college graduates, similar
to Facebook. Instagram is comprised of more female than male users, with a similarly aged audience as Twitter. While Instagram
users tend to have some college experience, they are not mostly college graduates like the previously discussed outlets. Lastly,
Pinterest is mostly made up of women, from a wide age range, and only about a third are college graduates.
In the world of veterinary medicine, Facebook is a great option for diving into the world of social media. To be successful on
Facebook, it does take a certain level of effort and finesse. Your practice must post relevant material for pet parents in order to
regularly appear in their feeds. If you are not precise in what you choose to post, it is possible you are wasting precious time trying to
reach out to an audience who isn’t listening.
The stories that tend to draw people in include patient stories, asking engaging questions, and celebrations. Patient stories are
usually very popular- be sure to get the owner’s permission, and post the case with a picture. Questions for your veterinary clients are
also a successful attention-getter: ask questions like what their pet is doing for the upcoming holiday, or ask your audience to caption a
funny animal photo. Celebrations draw a lot of “likes” as well- whether it be a team member’s professional accomplishment, a petrelated holiday, or a patient’s last chemo treatment.
Instagram is the next best social media option for veterinary practices. It focuses on sharing photos with followers, which is what
pet parents love to see on your feeds. It’s a great opportunity to share success stories and funny pet photos.
Blogging
Another great way to reach out to potential and current veterinary clients is through blogging. It’s easy enough to keep up, and also
cost-effective. This method helps establish your practice as an authority in the arena of veterinary medicine, and builds trust. Blogging
can serve as an easy method of creating viral material that reaches a large audience. If pet parents feel the information posted is
worthwhile, they often share this on social media which automatically widens your viewer base. This modern marketing initiative
helps initiate conversations with pet owners by allowing for commentary on your posts. If the material is educational and considered
valuable by your audience, you will also instill trust and credibility within the pet parent community.
Search engine optimization (SEO)
Your practice can put forth as much online marketing efforts as you like, but with a limited audience, your efforts will go unheard.
Search engine optimization (SEO) helps lengthen your message’s tentacles across the internet. SEO effects visibility through free
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methods (even better!). The idea here is that the earlier and more frequent a site appears in a pet owner’s search, the more viewers you
will obtain.
Some of the methods for SEO include editing content, HTML and coding to increase the site’s significance to searched keywords.
Content can be edited to include keywords that are frequently searched for, which can increase traffic to your site. Sites also can be
promoted by increasing backlinks and inbound links (a hyperlink back to your site from another site). Cross linking between pages of
a website can provide an increased number of links and help widen your audience. Content should be frequently updated as well so
search engines will regularly direct searchers back.
Videos
Incorporating videos into a practice’s marketing campaign helps add another fun and engaging element for pet parents, and can
ultimately increase visibility online. You can take the approach of sharing fun pet-related videos that you find, as well as making your
own, which can be educational or simply endearing or humorous. The key is to share and create videos that evoke emotion and portray
an image or viewpoint that is in line with that of your practice. Videos are often more likely to be shared, so they are much more likely
to become viral. It is important to already have your website and social media platform up to date and well established before you
begin to push videos. You wouldn’t want potential clients to stumble upon your Facebook account or website and find outdated or
minimally engaging material.
Review sites
Another element of a practice’s online presence is review sites. In today’s world, consumers can easily access reviews and ratings
from others on a multitude of review forums. While we all would like to find nothing but positive reviews under our name, when
negative commentary is added, it is imperative to take action quickly. It’s very important to start out by responding to any negative
posts, and do so with sincerity. This allows the public to see that you do care how you are perceived by the community, and want to do
right by your clients and patients. Reach out to any upset clients directly to discuss the situation further. Prior to that conversation, be
sure to research the situation so that you are knowledgeable during your talk and know if your practice truly was in the wrong.
Afterwards, if the hospital was at fault, be sure to hold a coaching session with the employees working with the client to ensure that
future clients receive a better experience.
Also remember to encourage those clients who rave on about your hospital at discharge to submit a review on the review site of
your choice. Many review sites even have signs, along with a unique QR code, which you can post in your hospital for clients to easily
find you (and hopefully provide you with a public kudos!). Links to your listing on a review site can be included on your practice’s
website as well as within the email signature.
Developing a strategy
The key to jumping into the waters of the modern marketing age is to start with a budget. It will cost money to develop a useful,
attractive website, and even the free options offer enhancements at a minimal cost that are worth exploration. The rule of thumb is
usually 3-5% of your net sales will go to marketing efforts.
The following steps are developing a plan and mapping it out on a calendar for the year. Before publicizing your practice, you
should be comfortable with your message. Your message should be direct, consistent and relatively straight-forward.
It is also worthwhile to consult with a marketing professional or company that has experience with veterinary practices. With the
right guidance and approach, your practice will outshine the competitors with ease.
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Going Back to Work after Baby and Beyond:
Tailor Your Career to Fit Your Life
Ori Scislowicz, BS, LVT
CVCA- Cardiac Care for Pets
Richmond, VA
One of the hardest struggles any working adult will face is the balancing act between work and life. Most in the veterinary field are
very passionate about their work, and along with commonly working long hours and emotionally tumultuous shifts, the struggle is
even more intense.
Step Away! Technology as one of the culprits
In today’s world, we are never completely turned “off”. We are generally just an arm’s length away from our phones, making us
available via text, call or email all hours of the day. Especially those in managerial and ownership roles may feel obligated to check
their work emails regularly at home and respond while they should be off-duty. In a 2011 study performed by the University of
Toronto, published in the Journal of Health and Social Behavior, researchers found that women who were contacted by their
supervisors, coworkers or clients frequently also reported higher levels of psychological distress. Men were less effected, which they
found was due to women harboring more guilt when responding to work matters at home.
Moving on up and other big life changes
Another component of the stress is that our Generation Y workforce is moving into management positions much quicker than their
older counterparts. This generation is very ambitious, and utilizes technology heavily, which allows them flexibility outside of work,
but also allows for them to be constantly available. Moreover, when you have younger individuals in management, they feel the
work/life balance burden even more as they are getting married, starting families, and still trying to grow themselves as people.
This brings us to the emotional experience of returning to work after having a baby. More women nowadays want to continue
working for financial and personal reasons. Your attempt at a balanced life becomes a lot more difficult when you have an
unpredictable, demanding little being in the midst. New mothers need not fret, there are many useful techniques for dealing with this
challenge.
Letting go of your perceived guilt for taking a break for yourself is the first step. Allow other family members, friends or your
spouse, to help out with the baby while you get time to yourself. Having time to rejuvenate- whether that be spent exercising, reading
a book or going out with some friends, helps make you a more well-adjusted person all around. It’s easier to give your all to your
child, family, work and other components of your life when you are taking care of yourself.
Reaching out to other new parents can also help make you feel less alone in this new endeavor, and can even help provide some
useful life tips. During the difficult spots of parenthood, being able to talk to other parents who probably have been there as well, can
be reassuring.
If your old schedule is simply not working with your new family, it is always worth discussing with your supervisor. Try to also
give some time after you initially return from maternity/paternity leave to settle back in, and make these big decisions when you are
less emotional. Thankfully, within veterinary medicine there are a multitude of career options offering different schedules. If working
in a clinic is no longer a good fit, it may be worth taking a leap into management, education, or exploring opportunities with veterinary
insurance and product companies, or research.
Delegation is a healthy habit almost everywhere- at work, and even at home. Although many of us can realize when it is necessary
to delegate tasks at work, we hesitate in the home environment. Getting help from a spouse, roommate or even your child (if they are
old enough) can help manage the chaos and your stress level. A lot of times one parent does not see how frazzled and exhausted the
other one has been until it is discussed. One of the best pieces of advice for a reduced stress life- don’t be afraid to ask for help.
The consequences of an imbalanced life
Not taking time for yourself and becoming overworked can wreck mental and even physical havoc on your body. When you work
long hours and never take time for yourself and your family, you become mentally depressed, helpless, and stressed. Physically you
may begin to exhibit psychosomatic symptoms (when mental stress manifests in physical ailments), such as headaches, stomach
ulcers, hypertension and chest pain.
The more exhausted and unfulfilled individuals become, the more they withdrawal from enjoyable activities and hobbies, along
with relationships. A mental switch is turned to think that personal life is getting in the way of work life, when it’s actually the
opposite.
Everyday life functions can be affected such as appetite and sleep. As you may guess, if you allow yourself to get to the point you
cannot appreciate life outside of work, it is important to remember that your work will indeed suffer as well.
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Getting out of the funk
In order to balance your work and life, you must take an active role in ensuring your own mental and physical health. Positive coping
skills can be broken down into the following categories: family, emotional, professional, spiritual, social and recreational.
It’s very important to have a support system, whether it be in the form of blood relatives, friends, or a partner. These individuals
help to provide an outsider’s perspective on how we are dealing with certain obstacles, and are also there for support.
Emotional coping skills include being aware when you begin to exhibit signs of burnout and stress and being able to separate
yourself from aspects of work that are activating a negative emotional response. This may be due to compassion fatigue or simply
spending too many hours at work and not enough time for your own life.
Professionally you can cope better with difficulties at work when you get help and advice from coworkers, and rejuvenate yourself
with continuing education opportunities.
You don’t have to go to church to take advantage of spiritual coping methods. Setting aside time for reflection and meditation can
help refresh your spiritual side. Getting in touch with the world around you and letting go of your problems for a few minutes every
day can help put life in perspective. Those issues that seemed so important and carried a lot of weight in your mind suddenly seem
insignificant.
Spending time with friends and your neighbors is great way to enrich your life and separate yourself from your own thoughts.
Getting involved in volunteer opportunities can also add a higher sense of purpose.
Lastly, recreational coping is a fun and exciting way to cope with life’s stressors. Starting up a new hobby or activity can help
make you feel more well-rounded and is a great stress reliever.
Time management
Identify what areas of your life are most important to you and discover how much time you spend on each aspect. This exercise will
help you decide where to make cuts and where to devote more of your time. Most of us will discover we are spending more time on
work or work-related thoughts than we should.
Adjusting your own self expectations and learning to say “no” to work-related activities that are intruding on your personal time is
an important step. Teach yourself not to feel guilty for taking time for yourself or for needing a change in your schedule at work.
Ultimately, we have to perceive our lives as chapters. The work/life balance struggle will be a constant mental project and an everchanging process. You will go through periods where you spend more time developing your career goals, and other periods where you
need to back off and spend more time and effort on other aspects of life, such as family. The key is taking the time to access your life
and make sure you are happy with where your journey is taking you.
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Avoiding Career Burnout
Dani McVety, DVM
Lap of Love
Lutz, FL
We have all experienced burnout in one way or another, in one form or another. It occurs when the purpose or motivation for work
evaporates and the practitioner no longer feels that the work is worthwhile. This may lead to a decreased ability to attach
professionally to, or care about, the next patient, or an overall sense of resentment for work that used to be fulfilling.
This elusive “fulfillment” from our work is something we each strive for, day after day. We were all once budding pre-veterinary
students, with nothing more amazing in our future than acceptance into vet school. It was everything to us, the golden ticket to the
perfect life, and we would have eagerly scooped 1 million more litter boxes with our bare hands if we would only be guaranteed
admission.
I have talked to hundreds of veterinary students at over 12 veterinary colleges in the past 8 months alone; I’m amazed how many of
them are still in this “stressed out” mind frame. Their life didn’t get stress-less when they entered graduate school, and it surely won’t
get better in the work force. They learn it in vet school, and I fear we never un-learn it, even when we walk across that stage to accept
our diploma. And now we wonder why we are discussing burnout with doctors that are less than a decade out of school.
Why are we graduating with our cup half empty? Why do the expectations of our career seem to be so un-aligned with reality? Is
this situation getting better or worse?
In this discussion, we will address some common themes associated with burnout in our careers. We will also use researchedbacked examples to illustrate some proven methods to acknowledge, overcome, and prevent the lack of fulfilment we call “burnout.”
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Puppies are Not Small Dogs:
Pediatric Emergencies
Garret Pachtinger, DVM, DACVECC
Veterinary Specialty and Emergency Center
Levittown, PA
Pediatric and reproductive emergencies are common in both general practice and the emergency room setting and can be both
extremely rewarding for the small animal practitioner. This lecture will focus on evaluation, diagnosis, and treatment of both the
pediatric and reproductive emergency patient.
Neonatal / pediatric emergencies
Unfortunately, just like cats are not small dogs, at times neonates and pediatrics are not just tiny adult dogs or cats either! There are
significant differences in the diagnosis, monitoring, and treatment of neonates and pediatric patients compared to adult patients. For
this reason, it is important that veterinarians become familiar with normal physical examination, hematological, biochemical, and
radiographic values for this age range.
In veterinary medicine, the term neonate is typically used from birth to 2 weeks of age and the term pediatric refers to patients
between 2 weeks and 6 months of age.
Neonatal / pediatric history
Common historical comments from the owners at the time of presentation include frequent crying, lack of/ineffective nursing, failure
to gain weight, lethargy, and weakness.
Neonatal / pediatric examination
The neonate / pediatric examination is at times a challenge based on their small size. A pediatric stethoscope is preferred for
auscultation. Several important differences will be emphasized as compared to adult patients.
•
The rectal temperature at birth is lower than adult patients, 95–98.6°F. This temperature gradually increases to adult
temperature (100-102.5°F) over 4 weeks.
•
A physiologic heart murmur may be ausculted up until 12 weeks of age without a primary cardiac defect / concern. If
the murmur is louder than expected or persists past 12 weeks, it is important to consider congenital disease. Other
pathology that may result in a neonatal/pediatric murmur includes fever, sepsis, or anemia.
•
Elevated heart rates in neonates (200 bpm in the normal neonatal puppies and 250 bpm in kittens) is common and
decreases to more normal resting heart rates at approximately 4 weeks of age. The decrease happens as parasympathetic
tone increases during that time.
•
Neonatal respiratory rates are often increased as compared to adult patients. Neonates have a smaller tidal volume and
increased pulmonary interstitial fluid, thus leading to a mild increase in both respiratory rate and effort.
Neonatal / pediatric clinicopathologic data
The neonate / pediatric bloodwork results can be quite normal, but differ considerably compared to adult patients. It is important to
recognize these common differences so further testing and/or treatment is not instituted without need.
•
The hematocrit (HCT) in neonatal puppies and kittens is lower than adult patients, reported to be 25-30% in the first 4
weeks of life, increasing to normal starting at 4-6 weeks of age.
•
Neonates normally have a mild increase in bilirubin (0.5mg/dl; normal adult range 0–0.4)
•
Alkaline phosphatase is often markedly elevated (ALP; 3845 IU/L, normal adult range 4–107)
•
γ-glutamyltransferase likewise is also quite elevated normally (GGT; 1111 IU/L, normal adult range 0–7).
•
Blood urea nitrogen (BUN), creatinine, albumin, cholesterol and total protein are lower in neonates compared to adults.
•
Calcium and phosphorous are higher in neonates.
•
Urine is isosthenuric in neonates as they do not yet have the ability to concentrate and dilute urine.
Neonatal / pediatric imaging
Radiographically, there are several anatomical differences as compared to the adult patient.
•
The thymus is located in the cranial thorax on the left side. According to Miller's Anatomy the thymus "is relatively
large at birth, grows rapidly during the first few postnatal months so that it reaches its maximum development before
sexual maturity, or between the fourth and fifth postnatal months, just before the shedding of the deciduous incisor
teeth. The thymus begins to involute with the changing of the teeth. Although the process is rapid at first, the organ does
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•
•
•
•
not atrophy completely even in old age." If this same opacity is seen in an adult patient, as compared to being normal in
a neonate/pediatric patient, this would more likely represent pulmonary disease or a mediastinal mass.
Pulmonary parenchyma has increased water content and appears more radiodense in neonates.
Neonates have a mild increase in heart size as compared to adults.
Neonates and pediatrics do not have prominent costochondral mineralization giving the appearance of the liver more
cranial, sitting under the rib cage.
Neonates and pediatric patients have decreased abdominal detail due to lack of fat as well as a normal, small volume
abdominal effusion
Neonatal / pediatric venous access and alternatives
Intravenous (IV) access is the preferred route for fluid and medication administration and when possible, should be performed. In the
event an IV catheter cannot be placed, placement of an intraosseous catheter is a reasonable alternative. Fluid or drugs administered by
this route are rapidly absorbed into the circulatory system. The most common sites for intraosseous access include the trochanteric
fossa of the femur, the greater tubercle of the humerus, the wing of the ilium and crest of the tibia. The author’s preferred site for IO
catheter placement is the proximal femur. The author commonly uses an 18–22 gauge hypodermic needle. Similar to an IV catheter,
an IO catheter can should be placed in an area that is prepared in a sterile manner. When placing an IO catheter, the needle inserted
into the bone parallel to the long axis of the bone. Following placement, the clinician should gently aspirate, then flush with saline to
assure patency. The catheter is secured with a bandage, suture, or tape preparation. Intravenous access should be attempted as soon as
possible following IO catheter placement, ideally within 2 hours to reduce the risk of complications from the IO catheter such as
infection, inflammation, or even fracture.
Neonatal / pediatric fluid therapy
Neonates have a higher percentage of total body water, a greater surface area to body weight ratio, a higher metabolic rate, more
permeable skin, decreased renal concentrating ability, and decreased body fat as compared to adults. For these reasons, neonates have
higher fluid requirements and must be treated accordingly.
•
Shock boluses of isotonic crystalloids are slightly higher in neonates, 30–40 mL/kg in puppies and 20–30 mL/kg in
kittens as compared to adults.
•
Maintenance rates of isotonic crystalloids are also slightly higher, reported to be 80–100 mL/kg/day.
It is important to keep the fluids warm due to the concern for hypothermic changes with large volume of potentially cool fluids in
neonates and pediatrics.
Neonatal / pediatric supplementation
Hypoglycemia is common in these patients due to a combination of factors including inefficient hepatic gluconeogenesis, decreased
liver glycogen stores, decreased intake, and loss of glucose in the urine as urinary glucose reabsorption does not normalize until
approximately 3 weeks in puppies. Gastrointestinal losses such as vomiting, diarrhea, as well as lack of intake also can exacerbate
hypoglycemia in neonates.
Critically ill neonates may require a dextrose bolus of 12.5% dextrose IV or IO (0.1 to 0.2 mL/100 g), followed by a constant-rate
infusion of 1% to 5% dextrose in a balanced electrolyte solution to prevent rebound hypoglycemia.
Neonatal / pediatric temperature regulation
Neonates have a greater surface area-to-volume ratio, impaired shivering reflex and decreased vasoconstrictive ability as compared to
adults and for this reason have an increased risk for hypothermia. Hypothermic patients should be rewarmed accordingly.
Neonatal / pediatric nutrition
If there is a concern for insufficient nutrition, often nursing from the bitch or queen, nutritional supplementation is recommended via
alternatives such as bottle-feeding and tube feeding. Tube feeding is performed using a small suction catheter or a 5-Fr red rubber
catheter for neonates under 300grams and an 8–10 Fr for larger neonates. It is important to confirm proper placement prior to milk
administration due to the risk for placement in the trachea and subsequent pneumonitis or pneumonia. Puppies are expected to double
their weight within 10 days of birth and gain 5–10%/day. Nursing kittens should also double their weight within the first 10 days of
life and normal kittens gain 10–15 g/day.
Postpartum emergencies
Dystocia
Dystocia is defined as the inability to expel fetus from the uterus and birth canal at the expected time of parturition. This is an
emergency that requires immediate attention to reduce both the risk of morbidity and mortality to the mother and fetus. Common
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causes for dystocia include a pelvic obstruction, an oversized fetus, fetal malpresentation, or fetal death. If possible, an attempt should
be made to manually remove the fetus if protruding from the vaginal vault. This is performed with a water-based sterile lubricant and
gentle traction wearing sterile gloves. Instruments that may injure the mother or fetus should be avoided if possible.
For patients with dystocia it is also important to correct any fluid, electrolyte, calcium, and glucose imbalances. Oxytocin is
commonly used, but important to understand the risks and why dosing currently is likely far less than what veterinarians used years
ago. Excess dosing of oxytocin can lead to tetanic and unproductive uterine contractions, placental separation and fetal hypoxia. It is
also important to identify obstructive dystocia, closed cervix, fetal distress, placental separation, uterine disease, an/or uterine rupture
prior to administration of oxytocin. If ruled out, oxytocin can be considered at 1–5 IU SC or IM repeating in 20-30 minutes if
ineffective. Calcium gluconate 10% as well as dextrose supplementation can also be considered if electrolyte support is a concern.
Uterine prolapse
Uterine prolapse may be seen during birthing or commonly within 48 hours following birthing when the cervix is open. Due to the
risk of infection, trauma and necrosis, immediate therapy is warranted. If appreciated early in the process, digital manipulation can be
attempted, replacing the uterus while the patient is under general anesthesia. If not found immediately, uterine tissue swelling
prevents successful digital manipulation and additional therapy may be needed. Hyperosmotic fluids such as 50% dextrose or
mannitol may decrease tissue swelling and assist with replacement. In more severe cases, an episiotomy or abdominal surgery are
needed to manually reduce the prolapse. If infection or necrosis is identified, ovariohysterectomy is indicated.
Retained placenta
Placentas should pass within 15 minutes of each puppy or kitten. Retained placentas carry the risk for metritis. Clinical signs of a
retained placenta and subsequent metritis include a foul smelling discharge, fever, vomiting, anorexia, and lethargy. While an astute
owner may report the failure of the placenta to pass, this can also be confirmed via ultrasound. Treatment with antibiotics, oxytocin, or
PGF2a can be considered.
Metritis
Clinical signs of metritis include anorexia, depression, lethargy, fever, and foul smelling vaginal discharge. Diagnosis of metritis is
based not only on history and examination findings, but often confirmed via abdominal ultrasound. Additional diagnostic findings that
can aid in the diagnosis include a complete blood count (leukocytosis with left shift) as well as a deep vaginal swab for culture and
sensitivity.
Hypocalcemia
Commonly referred to as eclampsia, hypocalcemia is a fairly common condition in bitches, notably small breed patients, 2–3 weeks
after delivery. It is uncommon in cats, but can occur. Signs of hypocalcemia include tremors, panting, stiffness, pacing, salivation and
restlessness. As it progresses the patient may exhibit worsening signs including tetany, hyperthermia, tachycardia, and seizure
behavior. The treatment of choice is 10% calcium gluconate; administered slowly with the patient monitored on ECG. The dose range
is 0.22-0.44mg/kg administered slowly IV until signs improve. Other signs such as dehydration or hypoglycemia should be treated
accordingly. Oral calcium treatment (500 mg TID per 20 lbs) as well as vitamin D (10,000-25,000 IU) should be continued throughout
the rest of lactation with the recommendation of removing the puppies from the bitch and supplemented with milk replacer, at
minimum for 12-24.
Mastitis
Mastitis is the term documenting inflammation of the mammary gland, commonly associated with infection. The most common
bacteria isolated include Staphylococcus sp. and Streptococcus sp. Clinical signs may be localized to one gland or throughout multiple
glands. The glands affected are often warm to the touch, painful, firm, and erythematous. Diagnosis is based on clinical signs, history,
cytology of milk confirms, and ideally culture and sensitivity. Broad spectrum antibiotics that achieve good concentration in milk
(cephalexin or clavamox).
References
Biddle D, Macintire D. Obstetrical emergencies. Clin Tech Small Anim Pract 2000;15(2):88-93
Davidson AP. Obstetrical monitoring in dogs. Vet Med 2003;6: 508.
Davidson AP. Dystocia management. In: JD Bonagura, ed. Kirk's Veterinary Therapy XIV. WB Saunders Co, Philadelphia, PA, in press.
Davidson A. Postpartum disorders in the bitch, queen & neonates. Western Veterinary Conference 2008.
Feldman EC, Nelson RW. Periparturient diseases. In: Veterinary Reproduction and Endocrinology. Philadelphia, WB Saunders, 1996.
Johnston SD, Root Kustritz MV, Olson PNS. The neonate - from birth to weaning. In: Johnston SD, Root Kustritz MV, Olson PNS, eds. Canine and
Feline Theriogenology, 1st edition. Philadelphia: WB Saunders; 2001:146–167.
Johnston SD, Root Kustritz MV, Olson PN. Canine and Feline Theriogenology. Philadelphia: WB Saunders Co, 2001
Macintire DK. Reproductive emergencies, Atlantic Coast Veterinary Conference 2006
Smith FO. Postpartum diseases. Vet Clin North Am Small Anim Pract. 1986;16(3):521-524
Wallace MS. Management of parturition and problems of the periparturient period of dogs and cats. Sem Vet Med Surg (Small Anim) 1994;9(1).
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Anemia:
It’s Not Only About Bleeding
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
Anemia, most accurately described, is a deficiency in the blood’s oxygen carrying capacity due to a reduction in the circulating red
cell mass. Measurement of total red cell mass requires specialized testing and is difficult to accomplish in clinical practice.
Measurement of PCV, HCT, hemoglobin (Hgb), and RBC count are more common methods in the assessment of erythrocyte content
of blood. Thus, anemia is commonly defined as a reduction in these values, and occurs when the rate of red blood cell loss or
destruction exceeds the rate of production. Anemia is caused by various diseases, many of them resulting in the patient requiring
immediate attention.
Functional role of red blood cells
Erythrocytes or red blood cells (RBCs) exist mainly to transport oxygen obtained through the lungs to body tissues. The cell’s
functions are devoted to optimizing oxygen delivery, with all of its potential energy directed towards maintenance of enzymatic and
hemoglobin function, as well as cell integrity. The general structure of RBCs involves a cell with no nuclei or organelle and no ability
to produce proteins. Therefore, a mature red blood cell must have its full set of proteins to function appropriately. The RBC’s oxygen
carrying capacity is very much dependent on hemoglobin, an iron-porphyrin-protein complex. Hemoglobin is synthesized during the
erythrocyte’s development to its mature form. The molecule is a tetramer of heme groups working in cooperation to load and unload
oxygen molecules. The percentage of heme groups bound to oxygen molecules is characterized by the oxygen-hemoglobin
dissociation curve, visualizing the relationship between partial pressure of oxygen in the blood vessel and oxygen binding. Affinity of
hemoglobin to oxygen can be affected by various factors, such as temperature, presence of hydrogen ions (pH), and presence of 2,3
diphosphoglycerate (2,3 DPG), altering the ability for transfused RBCs to deliver oxygen in specific conditions.
Erythropoiesis
RBCs are produced through a process called erythropoiesis. Hematopoietic stem cells are progressively differentiated into numerous
precursors, eventually expelling their nuclei and developing into reticulocytes, which develop into erythrocytes in 3-4 days. This
process is regulated by a hormone called erythropoietin (EPO), which signals for the production of new RBCs. EPO is a glycoprotein
produced mainly by the peritubular interstitial fibroblasts in the kidney, though the liver contributes to a small amount of production in
anemia. Autocrine production of EPO by erythroid progenitor cells has also been observed. There is a normal amount of
erythropoiesis, or basal erythropoiesis, which replaces RBCs living out its life span, maintaining the total red cell mass in a normal
range.
Upregulated erythropoiesis in response to an increased EPO production stimulated by inadequate oxygen carrying capacity and
resultant hypoxemia and hypoxia (leading up to a 1000-fold increase in severe hypoxia) is called stress erythropoiesis. Any cause for
anemia, such as hemorrhaging or hemolysis, can trigger EPO production with a noticeable increase in serum EPO level observed
within minutes. Reticulocytes are seen within 3-5 days after EPO level is increased, and take another 3-4 days to mature into
erythrocytes. Patients seen within 3 days after the blood loss are said to be in the “pre-regenerative” state with no increase in
reticulocyte count. If the blood sample of an anemic patient is showing increased reticulocyte count, the patient has a “regenerative”
anemia. Patients without an increase in reticulocyte count after 5 days of ongoing anemia may have “non-regenerative” anemia.
Normal RBC lifespan
Canine RBCs have a normal life span of 100-115 days, while feline RBCs normally live 73 days. RBCs are taken out of circulation as
age-related damage occurs. Age-related damage includes compromise in rheological properties due to membrane deformability loss,
immunologic removal through IgG binding and opsonization, reduction in antioxidant defenses leading to denaturing of hemoglobin,
and compromise to membrane structure through peroxidation of the phospholipid bilayer (oxidative damage). These damaged cells are
removed by the macrophages of the mononuclear phagocyte system, involving the spleen, liver and bone marrow.
Types of anemia
RBC loss
One of the most common causes of anemia is an increased rate of RBC loss. Blood can be lost through internal or external
hemorrhaging. Internal hemorrhage can involve blood loss into the internal spaces. such as peritoneal, retroperitoneal, pleural,
pericardial, and gastrointestinal spaces. There are numerous causes of internal and external hemorrhage. Trauma, surgical accidents,
and ruptured neoplasms can cause physical damage to vessels resulting in acute or gradual hemorrhaging. Coagulation factor
deficiencies, thrombocytopenia, and thrombocytopathia may render a patient unable to prevent bleeding from normal damage to the
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vasculature. Parasitism can lead to external hemorrhage (fleas, ticks, lice) or internal hemorrhage (Ancylostoma, Uncinaria).
Gastrointestinal ulcers and hemorrhagic gastroenteritis are GI specific sources of hemorrhage. Anemia due to hemorrhaging is usually
regenerative.
RBCs lost internally may be placed back into circulation through the lymphatic system, or removed from circulation by
macrophages, and their components are recycled. Plasma, RBCs, and its iron content cannot be recovered with external hemorrhaging.
Hemorrhage leads to a reduction in red cell mass as well as a compromise in perfusion, leading to reduced oxygen delivery. Dogs have
a total blood volume of 78-88ml/kg, while cats have a total blood volume of 62-66ml/kg. Blood loss exceeding 20% leads to
significant hypotension, and a loss exceeding 30% will lead to hypovolemic shock and possible death.
Treatment of RBC loss through hemorrhaging is directed at maintaining oxygen delivery through providing adequate perfusion and
oxygen carrying capacity. Fluid therapy to address hypovolemia is warranted to ensure perfusion to vital organs. Restoration of a
normal blood volume will not be possible without addressing the source of the hemorrhage. Locating the source of the blood loss may
be more obvious in the case of external hemorrhaging, but may prove to be a challenge if internal. Hemorrhaging from trauma,
surgical accidents, and ruptured neoplasms are often stopped through surgical intervention. Coagulation factor deficiencies warrant
replacement through appropriate plasma products. The cause of thrombocytopenia and thrombocytopathia should be addressed with
appropriate therapy, and platelet transfusions administered if the hemorrhaging is life threatening. Correction of hemostatic disorders
should ideally be accomplished before surgical intervention, if warranted. Ectoparasite and endoparasite infestations will require the
appropriate anti-parasitic. Gastrointestinal ulcers will require removal of causes and supportive care.
If the patient is showing a rapid decline in lab values related to red cell mass (PCV, HCT, or Hgb) or showing clinical signs of
hypoxia due to the anemia, a red blood cell transfusion is warranted. Clinical signs of anemia may vary slightly due to the cause of
anemia. In general, any form of anemia is associated with paleness. Patients who have compromised delivery of oxygen will exhibit
signs of weakness, exercise intolerance, lethargy, fatigue, and sometimes collapse. Their mentation may be dulled due to brain
hypoxia. In acute anemia, a prolonged capillary refill time (CRT) due to peripheral vasoconstriction to shunt blood to vital organs may
be seen (Patients with chronic anemia will show a normal CRT). Tachycardia, tachypnea, and bounding pulses without other
explanations also point towards compromised oxygen delivery.
RBC destruction
Various types of defects in RBCs can cause an increased rate of destruction leading to anemia. Anemia due to hemolysis results in
lowered red cell mass and subsequent reduction in oxygen carrying capacity without significant changes in plasma volume. Hemolysis
can be intravascular (destruction of RBC within the blood stream), extravascular (phagocytosis by macrophages in the spleen, liver,
bone marrow, and lymph nodes), or both. Intravascular hemolysis will result in the presence of free hemoglobin in the plasma, leading
to hemoglobinemia and hemoglobinuria (when renal threshold is exceeded). Hemoglobinuria leads to tubular necrosis resulting in
acute kidney injury in humans, and poses similar concerns in veterinary medicine. Jaundice may be seen in patients with RBC
destruction rate exceeding the liver’s ability to process bilirubin. In addition, the presence of red blood cell fragments may trigger
disseminated intravascular coagulopathy. Extravascular hemolysis can lead to splenic enlargement, though other intravascular signs of
hemoglobinemia, hemoglobinuria, and jaundice are not seen. Hemolytic anemia is usually regenerative.
Genetic defects of red blood cells, though rare, can cause hemolytic anemia. Elliptocytes, stomatocytes, and pyruvate kinase defect
lead to reduced life span due to abnormalities in RBC membrane and shape. Spectrin deficiency and phosphofructokinase defect lead
to reduced life span by increasing the fragility of RBCs.
Hemolysis is most commonly caused by acquired RBC defects, resulting in direct membrane injury or osmotic lysis. Exposure to
chemicals and drugs that cause Heinz body formation will lead to removal of these red cells from circulation through the phagocytic
system or cause direct lysis. Causes of Heinz body formation include toxins contained in food (onion, garlic, propylene glycol), drugs
(acetaminophen, vitamin K1 and K3, benzocaine), and chemicals (copper, naphthalene, skunk musk, zinc). Cats are more prone to
Heinz body formation, but are also more forgiving towards red cells containing Heinz bodies, allowing for a longer survival time.
Because of this, feline RBCs may show Heinz bodies without anemia. Cats can develop Heinz bodies when exposed to propylene
glycol, and are more prone if inflicted with diabetes mellitus, lymphoma, or hyperthyroidism. Cats with diabetes mellitus or hepatic
lipidosis can develop hypophosphatemia which also can cause hemolysis. Phosphate supplementation is recommended if a phosphate
level below 0.5mmol/L is seen. Intraerythrocytic parasites such as Babesia canis and Cytauxzoon felis, can lead to hemolytic anemia
as well.
Hemolysis may be caused by antibody or complement response to the surface antigens of red blood cells by the patient’s own
immune system, termed immune-mediated hemolytic anemia (IMHA). Extravascular hemolysis can result from an immunoglobulin G
(IgG) mediated type II hypersensitivity (cytotoxic) reaction. Phagocytic loss of RBC membranes reduces the surface area of the RBC,
leading to formation of spherocytes (RBCs that have lost the biconcave structure). Gross agglutination of red cells may also be seen. If
the immune response is initiated by factors such as cancer, drug administration, or infection, the hemolytic anemia is considered to be
secondary IMHA. Passive acquirement of anti-red cell antibodies through blood transfusions and colostrum can cause an IMHA as
well. The latter results in a phenomenon called neonatal isoerythrolysis, where anti-red cell antibody is passively acquired by a
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nursing neonate, resulting in the destruction of red cells. When no causative agents can be identified, the hemolytic anemia is
considered to be primary IMHA, or auto-immune hemolytic anemia (AIHA).
Changes in rheology and passage of RBCs through narrow vessels can cause mechanical and shearing damage to the membranes.
Hemoglobinemia and hemoglobinuria result as this is a form of intravascular hemolysis. Fragmented schistocytes and keratocytes are
seen on blood smears as an indication of mechanical damage. Patients with cardiac disease, severe heartworm infection,
hemangiosarcoma, patent ductus arteriosus, and any other causes of altered blood flow and microangiopathy may show signs of
fragmentation of RBCs. DIC can be a cause of fragmentation, and at the same time precipitate DIC.
Efforts in treatment of hemolytic anemia are directed towards removing the cause of the hemolysis, and supporting oxygen
carrying capacity as needed. Genetic disorders typically cannot be completely resolved, though patients with disorders leading to
hemolysis through the mononuclear phagocytic system may benefit from a splenectomy. Exposure to chemicals inducing Heinz body
related hemolysis should have the source removed (change in diet, surgical removal of the ingested copper or zinc material). Some
toxins may have antidotes such as acetylcysteine in acetaminophen toxicity. Therapy for mechanical injury induced hemolysis is
directed at the underlying cause. IMHA is treated with immunosuppressive agents such as glucocorticoids, cyclosporine,
mycophenolate, azathioprine, and intravenous immunoglobulin.
Regardless of the cause of the hemolysis, when the anemia leads to clinical signs of hypoxia, oxygen carrying capacity is
supplemented. Packed RBC (pRBC) transfusions are typically the ideal choice as hemolytic anemia does not cause blood volume loss.
pRBC will provide oxygen carrying capacity while minimizing the volume of transfused product, reducing the chances of fluid
volume overload. In the case of IMHA where finding compatible blood or simply judging compatibility may be difficult, hemoglobinbased oxygen carrier solution (HBOCS) administration may be beneficial.
Decreased production
Anemia can result from a reduced production of red cells as well. One cause for reduced red cell production is a decreased level of
EPO, leading to reduced erythropoiesis. Patients with chronic renal disease often become anemic as EPO production by the kidneys
are diminished. Other factors such as uremic toxins leading to a lowered red cell half-life, hemorrhagic loss due to GI ulcers, increased
bleeding tendencies due to platelet dysfunction, inhibition of iron store release, suppression of erythropoiesis by the parathyroid, and
reduced nutrient intake may also contribute.
Suppression of response to EPO is another cause of reduced production. In the presence of chronic inflammatory disease such as
chronic infections, chronic immune conditions, and malignant cancers, or in acute inflammatory diseases, red cell production is
reduced. This is attributed to an increased production of hepcidin by hepatocytes during inflammatory disease, which inhibit the iron
exporting action of ferroportin in macrophages and enterocytes. This reduces the iron available for erythropoiesis. In addition,
inflammatory mediators (tumor necrosis factor-α and interleukin-1) released from leukocytes reduce surface EPO receptors on
erythroid stem cells, leading to suppression of erythropoiesis.
Dysfunction of the bone marrow may be another cause for reduced RBC production. Irradiation, toxicities, viral or bacterial
infections, and administration of certain drugs can result in marrow aplasia, leading to a lack of marrow stem cells. Myelopthisis, or
marrow suppression secondary to marrow infiltration by tumors can displace or inhibit production of hematopoietic cells. Both of
these situations result in a pancytopenia. In FeLV infections in cats or immune-mediated erythroid stem cell destruction in dogs,
erythrocyte precursor cells are specifically reduced in number, leading to red cell aplasia.
When nutrients required for producing the signaling system for erythropoiesis and functional erythrocytes are deficient, anemia
will occur. Folic acid, vitamin B12, cobalt and intrinsic factor (a glycoprotein aiding in absorption of vitamin B12) deficiency can
result in a dysfunction of DNA and RNA synthesis, leading to production of erythrocytes of abnormal shape and size. These abnormal
cells are destroyed in the bone marrow, thus never making it into circulation. Administration of drugs that antagonize folate
(methotrexate for malignant tumors), inhibit folate metabolism (sulfonamides), and deplete folate concentrations (phenobarbital) are
potential causes of malformed erythrocytes. A genetic disorder in Giant Schnauzers, Beagles, and Border Collies involving selective
malabsorption of vitamin B12 has been reported and lead to a non-regenerative anemia. A deficiency in iron results in production of
erythrocytes with a reduced concentration of Hgb, or lead to delay in red cell production resulting in anemia.
Treatment for non-regenerative anemia consists of supportive care while the underlying disease process is treated. Infectious and
toxic causes may be alleviated over time, yet neoplastic and genetic causes typically have no complete resolutions. Ineffective
erythropoiesis due to nutrient deficiency can be alleviated through supplementation. In the case of decreased EPO levels, such as
chronic kidney disease, EPO may be administered to promote erythropoiesis. If the anemia reaches a point of clinical signs of
hypoxia, administration of red cell products or HBOC solution may be beneficial.
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CPR:
The RECOVER Guidelines
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
In June of 2012, the Reassessment Campaign on Veterinary Resuscitation (RECOVER) published the first evidence based guideline
for veterinary cardiopulmonary resuscitation (CPR). The initiative was launched after considering the difference in success rates of
CPR between human (20%) and veterinary (6-7%) settings, with the human counterpart having established evidence-based guidelines
through the American Heart Association. There are definitely physiologic and anatomic differences between human patients and
veterinary patients, but one would expect a comprehensive, evidence-based treatment strategy on execution of CPR to improve the
outcome through optimization of the CPR protocols. The RECOVER initiative was carried out through the involvement of over 80
experts from the American College of Veterinary Emergency and Critical Care (ACVECC) and American College of Veterinary
Anesthesia (AVTA) of multi-national background evaluating published studies available to answer clinical questions organized into 5
different subtopics to arrive at a consensus guideline. This groundbreaking effort not only produced a guideline that is now utilized all
over the world to refine CPR practices, but has also injected fuel into the drive towards evidence-based practices in veterinary
medicine, and sparked many other movements in the process.
Evidence in CPR
Many clinical questions asked in 5 different “domains” of (1) Preparedness & Prevention, (2) Basic Life Support, (3) Advanced Life
Support, (4) Monitoring, and (5) Post-Cardiac Arrest Care were answered to confirm or disprove existing beliefs, provided new
knowledge, and also allowed us to identify gaps in the knowledge available to come to definitive answers.
The guideline emphasizes importance in early initiation of CPR as a key factor in successful outcome. Preparation for swift
intervention when a patient going into cardiac arrest can be accomplished through thorough training of the staff in both didactic
(knowledge) and psychomotor (physical) aspects of CPR. CPR drills simulating the arrest and response allows staff members to better
understand the sequence of events and potential turns the event may take. Periodic refresher training sessions at least every 6 months
is recommended. Preparation of the facility through setup of a crash cart in a central location, which is regularly checked for stock
with a detailed checklist will allow for easy access to supplies and equipment required for CPR. Cognitive aides consisting of the CPR
algorithm, drug dosage charts, CPR priority checklist should be readily available in the emergency area, with the staff trained on their
usage prior to the event, helping adherence to proper protocol.
Swift intervention is better made when cardiopulmonary arrest (CPA) is recognized quickly, and CPR initiated. Assessment of the
patient for CPA should be performed in no more than 10-15 seconds through a standardized approach. If CPA is even suspected, chest
compressions should be started right away since any delay can significantly reduce the chance of success, accurate assessment of a
lack of a pulse is difficult without taking a long time, and performing compressions on a patient that is not in CPA brings very little
harm. In an inpatient situation, clear identification of patients at risk of CPA to the staff should allow for earlier recognition.
Basic life support
CPR starts with provision of basic life support (BLS) as the priority, and most important aspect of CPR. The mnemonic CAB is now
used to describe the priority order of circulation, airway, and breathing, because breathing is not helpful in oxygen delivery if
circulation of blood has ceased. Evidence points towards delay in initiation of compressions leading to lower success rates in CPR. In
regards to compressions, there were no differences seen between right and left lateral recumbency. Chest compressions should be
performed to 1/3 to 1/2 of chest width (which takes quite a bit of force for large animals, while moderation may be required for
smaller patients) at a rate of 100-120 compressions per minute while allowing full chest recoil in between. The compressions should
be focused at the highest point of the chest for dogs with normal conformation, over the heart for keel-chested dogs, and over the
sternum in flat-chested dogs (such as some bulldogs). Small dogs and cats should have compressions performed over the heart, and
compressions may be performed with a circumferential or two-handed technique. The use of a metronome, songs, or other methods of
keeping the rate consistent to recommended rates is useful. Even when compressions are executed properly, it may only produce about
30% of normal cardiac output, which illustrates the need for swift and proper compressions during CPR. Interrupting of compressions
significantly reduces the forward flow created through consistent application of compressions, and is best avoided. Compressions
should not be stopped to auscultate the heart, check for pulses, assess the patient, or place an endotracheal tube for a full 2 minutes per
cycle of compressions. 10-15 seconds in between 2 minute cycles should be used for assessment of the patient, and compressions
resumed promptly if no change in CPA is seen. The compressor should be switched between cycles as well, to prevent physical
fatigue as 2 minutes of repetitive compressions is physically demanding.
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The airway should be verified to be patent, and any obstructions dislodged. Endotracheal intubation should be performed without
interruption of compressions, and ventilations performed approximately at 10mL/kg tidal volume (or 20cmH2O of pressure if no
spirometer) at 10 breaths per minute with an inspiratory time of 1 second. Hyperventilation is best avoided to prevent vasoconstriction
from low CO2 levels leading to poor cerebral perfusion. Mouth-to-snout ventilation may be used if supplies for endotracheal
intubation are not available. In the case of single person CPR, 2 short breaths in between 30 chest compressions is recommended.
Advanced life support
With basic life support provided, the attention of the CPR team should be directed to providing advanced life support, including
monitoring, drug therapy, and electrical defibrillation. The two forms of monitoring that prove useful during CPR is the
electrocardiogram (ECG) and end-tidal carbon dioxide (ETCO2) monitoring. Pulse oximeters and oscillometric or Doppler blood
pressure monitoring is not effective in assessment during CPR due to movement and poor perfusion state. The electrocardiogram is
also prone to motion artifacts during compressions, making interpretation difficult. Regardless, specific tracings may be seen during or
in between compression cycles, guiding therapy. Asystole, pulseless electrical activity (PEA) and ventricular fibrillation (VF) are
notable arrhythmias seen in CPR.
Capnography, or measurement of CO2 in the breaths coming out of the patient is monitored easily in a patient that is
endotracheally intubated. ETCO2 measurement is the most reliable form of monitoring for effective compressions since the level of
CO2 measured correlates to the level of perfusion the lungs are receiving, given there is no severe pulmonary pathology. ETCO2
levels higher than 10-15mmHg during CPR was observed to give a higher chance of return of spontaneous circulation (ROSC). Upon
ROSC, ETCO2 increases significantly as perfusion to the lungs are re-established, and can be used as an indicator of ROSC.
Drugs can be administered intravenously (IV) or intraosseously (IO) during CPR, and access should be established without
interruption of compressions. Vasopressors, parasympatholytics, anti-arrhythmics, reversal agents, IV fluids, and alkalinizing agents
are used in specific situations during CPR. Vasopressors are indicated for use in CPR regardless of ECG readings to increase systemic
vascular resistance and optimizing perfusion through the reduced cardiac output. Epinephrine, an alpha-1, beta-1 and beta-2
adrenergic agonist causes vasoconstriction, and is given at a low does (0.01mg/kg) initially, and at a high dose (0.1mg/kg) with
prolonged duration of CPR. Vasopressin is an alternative that may be used in place of epinephrine at 0.8U/kg. Both vasopressors are
given every other cycle of compressions due to its half-life.
Atropine has traditionally been given as an anticholinergic and a sympatholytic drug. There is minimal evidence indicating benefits
of atropine administration during CPR, though there is also no evidence of harm. Atropine is given at 0.04mg/kg IV or IO at the
initiation of CPR or as soon as IV or IO access is established, with redosing performed every other cycle of compressions. Antiarrhythmics may be useful in ventricular fibrillation (VF) that does not respond to electrical defibrillation. Amiodarone at 2.5-5mg/kg
IV or IO is recommended, with lidocaine at 2mg/kg slow IV or IO being a secondary option. Reversal of any anesthetic or analgesic
drugs seems reasonable though no evidence is seen. Opioids can be reversed with naloxone (0.04mg/kg), benzodiazepines with
flumazenil (0.01mg/kg), and alpha-2 agonists with atipamezole (0.1mg/kg) or yohimbine (0.1mg/kg), each IV or IO.
Intravenous fluids may be beneficial if the patient is known or is suspected of hypovolemia to help restore intravenous volume and
perfusion, but is unlikely to be of any benefit (and may even be detrimental) to those that are euvolemic or hypervolemic.
Corticosteroid administration may have been traditionally performed, though evidence suggests more potential harm than benefits,
discouraging its use. Sodium bicarbonate administration is considered in patients with prolonged CPA (10-15 minutes) to counter
effects of metabolic acidosis which is likely to be present.
Electrical defibrillation is useful in patients with VF and has been associated with a higher rate of ROSC. Electrical defibrillation
delivers an electrical shock to the heart “resetting” the myocytes and allowing them to resume a more orderly conduction and
contraction pattern. Monophasic and biphasic defibrillators are available on the market. Biphasic models are recommended over
monophasic because of the higher success rate and less damage caused by a lower current used. Defibrillation should be performed in
between compression cycles to minimize interruptions and allow for recharging of the defibrillator should repeated discharges be
necessary.
Post-resuscitation care
The survival to discharge rate of a patient that successfully achieves ROSC is quite low, reported to be 16% in one veterinary study.
The final outcome has a multitude of factors including underlying disease, the cause of CPA, and damage to tissues sustained during
and after CPR. Post-resuscitative care is directed towards respiratory optimization performed through monitoring and providing
adequate ventilation and oxygenation, hemodynamic support with IV fluids, vasopressors, and inotropes as indicated, and
neuroprotective therapy consisting of seizure control, permissive hypothermia, and intracranial pressure control. Optimization of the
respiratory, cardiovascular, and nervous systems allows the best chance for patient life to continue while the underlying disease is
treated.
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Non-medical aspects
Even when patients at risk of CPA are identified ahead of time and the team is prepared with the appropriate facilities to perform CPR,
administration of CPR can be quite chaotic. The aim is to bring as much organization and order to the chaos as humanly possible. One
of the biggest factors to keeping the order is the organization of a team. There are several roles to be established ahead of time in
training for any one person to be comfortably able to fill all roles necessary. The roles needed are: CPR leader, compressor, ventilator,
record keeper, drug handler, and the veterinarian. The CPR leader should be identified at the beginning of CPR, so assigning of
subsequent tasks can begin immediately. Staffing permitting, the CPR lead should be freed from tasks aside from assigning and
keeping the team organized. Compressor and ventilators provide the compression and ventilation, and may make sense to alternate
with each other between compression cycles if staffing is limited. The record keeper should keep a detailed medical record during
CPR, and this task is facilitated with a CPR record form. The drug handler will prepare and administer drugs in most cases. The
veterinarian ideally is not fulfilling any of these roles, being able to focus on the patient and making judgments on whether CPR
efforts should continue, decisions on drug administration, communication with the owners, and any medical interventions that are
necessary for the patient.
Communication during CPR is also vital to inn organizing the effort and preventing mistakes. Closed-loop communication,
performed through the person making a request addressing an individual clearly by name, the addressed individual repeating back
their understanding of the request, the request being fulfilled being announced, and the requestor acknowledging the completion.
Keeping the communication loops closed each time may feel awkward if it is not used on a regular basis, but contributes to very
organized communication allowing everyone on the scene to stay on the same page on the status of the CPR. Double checking each
other on tasks being performed is also possible, preventing the preventable mistakes.
Debriefing is another form of communication that is hugely beneficial for the team, regardless of the outcome. After the conclusion
of CPR, every member should participate in a 5-15 minute debriefing session discussing the CPR. The discussion will be lead by the
CPR lead, discussing the following points:
1. What went well with this CPR session?
2. What could we have done differently?
3. Are there any goals we can set for ourselves for future CPR sessions?
4. Are there any serious concerns you would like to bring up?
Debriefing sessions will bring your team even closer together as a functional unit. This also provides opportunities for staff
members to express any stress they may have faced in a productive and constructive manner, and a chance for better understanding of
the event that passed. Debriefing is intended for us to be able to think towards bettering our effectiveness in CPR, providing each
individual patient the best possible chance of recovery and positive outcome. Bring your open mind, active listening, and participation
to each of these debriefings. Commend each other on what was done well, regardless of the outcome. Discuss what could be done
differently to perform CPR better. Every opinion is important, and should be discussed in a professional manner. Being open in
communication requires trust and willingness to give and take feedback without bias and being personally affected.
Has RECOVER made a difference?
In the first year since the implementation of the RECOVER guideline into our CPR training protocol, a total of 54 CPR efforts (35
dogs,18 cats, 1 chinchilla) have been made at the author’s practice (data collection for the second year is ongoing). The average age
was 9 years old, with variable reasons. The average duration of CPR was 11 minutes, with the shortest effort lasting 1 minute and the
longest 32 consecutive minutes (one effort lasted 47 minutes total, with intermittent ROSC). The ROSC rate was 24.1% (13 of 54),
with a survival-to-discharge rate of 3.7% (2 of 54). The average duration of CPR effort achieving ROSC was 9.5 minutes (high: 27,
low 1). One of the patients who were eventually discharged was suspected to have experienced hyperkalemia related cardiac arrest
from urinary obstruction, while the other was suspected to have suffered from severe metabolic acidosis and potential oversupplementation of potassium as insulin doses were reduced without a change in KCl content of IV fluids (diabetic ketoacidosis
patient). Comparison with previously published statistics unfortunately does not yield a significant difference at our practice. The
staff, however, feels better prepared for the ultimate emergency, and feels confident the best chances are provided for each of our
patients.
Other effects of RECOVER
RECOVER has brought on some indirect changes to the veterinary field in addition to providing standardization of CPR protocols.
The Academy of Veterinary Emergency and Critical Care Technicians (AVECCT) is in the process of using similar evidence grading
methods used by the RECOVER initiative in creating evidence-based nursing guidelines, inspired by the initiative. Evidence-based
veterinary medicine (EVBM) has gained significant momentum since RECOVER guidelines were published, and while this could be
temporally a coincidence, there is no denying the initiative adds significant weight to the importance of EVBM. ACVECC is now
offering a college sanctioned veterinary CPR BLS training program through Veritas, offering certification for both didactic and
psychomotor training. The training program, in the long term is anticipated to reach the public. As the immediate next steps, an
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advance life support course is being designed, and a trainer certification program is also in the works. Advancement in the field of
veterinary emergency and critical care has been accelerated due to the RECOVER initiative.
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Just Breathe!
Respiratory Emergencies
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
Respiratory distress is a very common form of emergency in veterinary medicine. The primary role of the respiratory system is to
oxygenate and control CO2 levels in the blood. Inability for patients to properly oxygenate blood and saturate hemoglobin
(hypoxemia) will lead to inadequate delivery of oxygen to the tissues (hypoxia). In a hypoxic state, cellular energy production is
shifted primarily to anaerobic metabolism, resulting in lactic acid buildup and acidemia (metabolic acidosis). In addition, insufficient
alveolar ventilation will lead to an elevation in the arterial CO2 level, or hypercapnia. Hypercapnia leads to respiratory acidosis,
decreases cardiac contractility, and depresses diaphragmatic function. Both of hypoxemia and hypercapnia, when allowed to persist,
will lead to the demise of a patient and swift assessment of respiratory compromise is required for appropriate treatment.
Initial assessment and treatments
Assessment of a patient starts with external physical signs. Patients presenting with signs such as tachypnea, increased respiratory
effort, and open-mouth breathing are clearly in trouble. Exaggerated movement of parts of the body surrounding the physical construct
of the airway such as flaring nostrils, lip movement with respiration, sucking in and out of the skin under the chin and thoracic inlets,
and paradoxical abdominal movement are all signs of significant effort. An orthopneic position, characterized by open-mouth
breathing, extending of the head and neck, sitting up sternal, and abduction of the elbows in the effort to open up the airway as much
as possible, is another external sign of respiratory distress. If the patient progresses to being unable to hold themselves up, going into
lateral recumbency with no improvement in respiratory signs, the patient may be experiencing fatigue and facing imminent arrest.
Assessment and treatment of a patient in respiratory distress poses a dilemma, as swift determination of the patient’s problem is
required, yet they may be compromised such that the stress of diagnostics and treatment may push them into respiratory and cardiac
arrest. These patients are in a very fragile state, and initial efforts are aimed at improving the patient’s ability to breathe while
minimizing stress and deterioration in respiratory status. Providing oxygen supplementation through flow-by, mask, induction
chamber, or cage would be one of the first lines of therapy to alleviate distress.
Patients in respiratory distress are often very anxious, which often makes the patient even more dyspneic. A light sedation with
small doses of benign sedative such as butorphanol may be beneficial to help ease anxiety. The staff working on the patient should
conduct themselves in a calm and quiet manner yet maintaining swiftness. A calmer environment will not only benefit the patient, but
may benefit a worried owner. The presence of the owner can either be beneficial or detrimental to the patient, and staff directing
attention to calming a panicked client (and successfully doing so) may also help the patient.
Diagnostics and treatment such as physical examination, radiographs, blood work and IV catheterization may have to be held off
until the patient is more relaxed and breathing better. Evaluation of a patient’s respiratory problem begins with external visualization
of their breaths. The manner in which a patient breathes is adapted to the method requiring the least work of breathing. An obstructive
breathing pattern, involving a prolonged inspiration (upper airway) or expiration (intrathoracic lower airways), will be observed in
patients with narrowed airways. A restrictive breathing pattern, involving shallower but tachypneic breathing, will be observed in
pleural disease or reduction of lung compliance. Abdominal effort may be seen with patients with compromised lungs. Certain
conditions (anemia, metabolic acidosis, and pain, for example) can cause “non-respiratory look-alikes”.
Auscultation is a valuable skill in early detection and detection of change in lung states. Stertor (snoring), wheezes (whistling), and
stridor (high pitched noise) can indicate different upper airway issues. Crackles indicate fluid in the alveoli, such as in pneumonia or
pulmonary edema. The location lung sounds are present or absent in helps indicate causes as well. Cardiogenic pulmonary edema
often begins near the heart (perihilar region), and aspiration pneumonia often originate in the cranioventral lobes. Absence or decrease
in lung sounds in the caudal and ventral fields may indicate pleural effusion, while dorsal fields may be due to pneumothorax. While
abnormalities in auscultations do not lead to a diagnosis, it serves as an indication for further diagnostics.
If a pleural space issue like pleural effusion of pneumothorax is suspected, performing thoracocentesis to evacuate the fluid or air
can provide diagnostic information and therapeutic treatment simultaneously. The staff should be prepared to perform endotracheal
intubation and provide positive pressure ventilation (PPV) if the patient does not stabilize with initial treatment and deteriorates.
Types of respiratory emergencies
Upper airway problems
Upper airway issues leading to respiratory distress are common in veterinary medicine, and can involve various causes. Laryngeal
paralysis is common in older, larger breed dogs, with a higher prevalence in males. A loss in innervation of the cricoarytenoideus
dorsalis muscle leads to atrophy, preventing the arytenoid cartilage from being abducted. The laryngeal opening is narrowed, leading
to an increase in airway resistance. Causes may be congenital or from trauma, neuromuscular disease, neoplasia, hypothyroidism, or
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idiopathic. Affected dogs exhibit inspiratory stridor, exercise intolerance, ptyalism, and a change in their bark. Laryngeal paralysis can
cause severe respiratory distress and collapse depending on severity. Emergency stabilization involves endotracheal intubation. Once
stabilized, medical management may be possible with the goals of minimizing stress, excitement, and exposure to high environmental
temperature. Surgical treatment is most effective, involving unilateral lateralization of the arytenoid cartilage, or laryngeal tie-back.
Chances of aspiration pneumonia are increased in dogs undergoing this procedure. Cats rarely present with laryngeal paralysis, though
a study suggests laryngeal paralysis a differential for cats with dyspnea, inspiratory stridor, coughing/gagging, or a change in voice,
with complete resolution through unilateral lateralization.
Brachycephalic syndrome results from anatomical abnormalities seen in brachycephalic breeds leading to upper airway narrowing
or obstruction. Stenotic nares, enlarged tonsils, and elongated soft palate require the breed to create larger negative pressure to breath
normally, creating a narrowed airway from hyperplasia of the airway beyond the nares. A further increase in negative pressure may
evert laryngeal saccules and collapse the larynx or trachea. Pulling of air through the narrowed airways can further cause inflammation
and edema, placing the patient in further respiratory dysfunction. Surgical intervention through widening of the nares, resection of the
palate and everted laryngeal saccules, and removing the tonsils is the recommended treatment. In addition, upper airway obstruction
may occur due to lodging of a foreign body, neoplasia, or the formation of nasopharyngeal polyps. Any upper airway dysfunction or
obstruction can lead a patient to present with respiratory distress. Secondary complications such as non-cardiogenic pulmonary edema,
heat stroke, and aspiration pneumonia may be seen.
Pulmonary edema is a common cause of respiratory distress in dogs and cats. Accumulation of extravascular fluid occurs in the
alveoli and pulmonary parenchyma due to increased hydrostatic pressure or increased permeability in the pulmonary vasculature.
Patients present with respiratory distress and have poor oxygenation. The reduced oxygenation is due to a ventilation-perfusion
mismatch (V/Q mismatch) because the presence of fluid in the alveoli leads to compromised ventilation.
Left sided heart failure can lead to pulmonary hypertension, causing cardiogenic pulmonary edema. In cardiac disease, fluid
retention and an increase in blood volume is seen as a compensatory mechanism for lowered cardiac ouput. The chronic increase in
blood volume leads to an increased hydrostatic pressure (because of congestion) in the pulmonary vasculature, resulting in pulmonary
edema. Patient with cardiogenic pulmonary edema may show signs of coughing, exercise intolerance, and may have a heart murmur.
An echocardiogram may be performed to confirm cardiac disease and pulmonary hypertension. Fluid volume overload through fluid
therapy is a possible cause of cardiogenic pulmonary edema, especially in patients with cardiac or kidney disease. Both cardiac and
kidney disease can be asymptomatic, so patients on fluid therapy should be closely monitored for signs of fluid overload.
Non-cardiogenic pulmonary edema can occur from increased permeability within the lung tissue through damage to the
microvasculature or alveolar epithelium. Electrocution, seizures, strangulation, pulmonary thromboembolism, and chemical exposure
are all potential causes. Illnesses associated with systemic vasculitis such as sepsis and systemic inflammatory response syndrome
(SIRS) are also associated with non-cardiogenic pulmonary edema.
Patients with pulmonary edema are treated with oxygen to alleviate hypoxemia. Patients that are unable to maintain an arterial
partial pressure of oxygen (PaO2) greater than 60mmHg despite oxygen therapy may require endotracheal intubation and PPV. An
arterial blood sample and a blood gas analyzer are required to obtain a PaO2 measurement. Placement of an arterial catheter is
beneficial in serial monitoring of PaO2. PPV is also indicated if the arterial partial pressure of CO2 (PaCO2) is greater than 60mmHg.
A venous sample is acceptable in measuring CO2 levels (PvCO2 for venous) and is typically within 5mmHg from arterial values.
Some patients may have a positional “preference” in their ability to oxygenate and ventilate, with sternal recumbency usually being
most beneficial.
Medical management of the cause of pulmonary edema is warranted in conjunction with respiratory support. Diuretics are
administered to reduce pulmonary capillary pressure and reduce preload through reduction of blood volume. Furosemide is a
commonly used diuretic due to its rapid onset. In addition to its diuretic effect, furosemide may have further beneficial effects of
pulmonary vasodilation and bronchodilation. Hemoconcentration resulting from reduced intravascular volume increases the plasma
colloid osmotic pressure, helping the removal of fluid from the alveoli. Nitroprusside and glycerol trinitrate are vasoldilators that may
be used as an additional method in reducing hydrostatic pressure. Bronchodilators such as terbutaline may also be used, and fluid
therapy restricted. Chances of resolution depend heavily on the cause, and treatment for the patient’s specific underlying disease is
required.
Pleural space disease
When the pleural space which normally serves to create negative intrathoracic pressure during breathing is filled with material which
normally do not exist, normal breathing is compromised. The material may be various types of fluid, air, or even organs. The pleural
space being occupied by these abnormal substances will cause the lunges to collapse and prevent adequate inflation, leading to a
decrease in tidal volume, total vital capacity, and functional residual capacity. The lung volumes lead to hypoventilation, which can
result in hypoxemia and hypercapnia.
Accumulation of fluid in the pleural space is called pleural effusion and can be of various type. Hydrothorax, or accumulation of
transudate can be a result of reduced plasma colloid osmotic pressure, increased hydrostatic pressure, increased vascular permeability,
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or neoplasia. Transudate is defined as effusion containing TP < 2.5g/dl and total nucleated cell count (TNCC) < 1500/µl. Effusion
with TP between 2.5 and 7.5 g/dl and TNCC between 1000-7000/µl is considered to be modified transudate. Effusion with TP >
3.0g/dl and TNCC > 7000/µl is defined to be exudate.
Feline infectious peritonitis (FIP), caused by a coronavirus can cause exudative or modified transudate effusion with yellow to
straw-colored, viscous fluid with a high protein but low TNCC. Pyothorax is an accumulation of purulent exudate in the pleural space.
Causes include bacterial infection due to migrating inhaled foreign objects, penetrating trauma to the chest wall, pneumonia, migrating
plant material, and iatrogenic causes. Patients with pyothorax are typically treated with supportive care, antimicrobial therapy, and
chest tube placement for intermittent lavaging with physiologic saline. In some cases, surgical exploration of the chest cavity to
remove the source of the infection may be chosen. Accumulation of pink or white, milky, chylous effusion is termed chylothorax. The
opaqueness is a result of a high triglyceride concentration. Potential causes include cardiomyopathy, congestive heart failure,
pericardial disease, thoracic duct obstruction or rupture, lymphosarcoma, thymoma, and lung lobe torsion. Patients with chylothorax
are typically managed by removal of the effusion through thoracocentesis. Hemothorax can result from coagulopathy, trauma,
neoplasia, lung lobe torsion, pulmonary thromboembolism, and thymic hemorrhage. Iagtrogenic causes are also possible, from
procedures such as thoracocentesis, thoracostomy, and intrathoracic biopsy.
An open pneumothorax can result from penetrating thoracic trauma. Closed pneumothorax can occur due to damaged lung
parenchyma, trachea, airway, esophagus, mediastinum, or diaphragm. Traumatic pneumothorax is the most common type of
pneumothorax, caused by blunt force trauma such as automobile accidents or falling from heights. Gradual accumulation of air and
pressure due to the lesion acting as a one-way valve results in a tension pneumothorax. A tension pneumothorax is life-threatening;
increased intrathoracic pressure causes cardiovascular depression through reduction of venous return, leading to shock. Immediate
thoracocentesis, and in persistent tension pneumothorax, a thoracostomy tube may be placed to continuously evacuate air out of the
chest cavity. This is accomplished with a continuous suction device, or a one way valve. The patient is monitored for subsequent
occurrences of dyspnea, indicating a return of pneumothorax. If a closed pneumothorax does not resolve in 3-5 days, surgical
exploratory is warranted.
Diaphragmatic hernia may occur due to trauma or could be congenital. The degree of dyspnea varies depending on the degree of
herniation, presence of concurrent pleural effusion, and presence of thoracic injuries. Surgical treatment is warranted when
diaphragmatic hernias are seen, and should be performed immediately if any organ torsion or strangulation is suspected. Prognosis is
good in patients receiving surgical intervention within 24 hours.
Pneumonia is the inflammation of the pulmonary parenchyma caused typically by an infectious agent which enters the airway.
Aspiration pneumonia is caused by inhalation of contaminated material leading to an infection. Patients with aspiration pneumonia
may present in respiratory distress and exhibit signs like coughing, weakness and collapse, pyrexia, cyanosis, and purulent nasal
discharge. Lung sounds will be loud, and crackles may be heard. Abnormal sounds more often than not can be localized in the
cranioventral areas. Treatment will consist of antimicrobial therapy, oxygen therapy and mechanical ventilation if necessary. Nursing
interventions such a nebulization and coupaging may be instituted, though human evidence relating to a faster recovery from
pneumonia has not been seen.
Patient monitoring
During the treatment of patients with respiratory compromise, the patient should be closely monitored on three different aspects;
oxygenation, ventilation (carbon dioxide elimination), and the degree of respiratory effort. In addition to the visible respiratory effort
and auscultation, different instrumentation and blood analysis can give insight to the progression of the patient’s recovery.
Oxygenation
A physical sign seen in patients with severe hypoxemia is cyanosis, or a blue color to the mucous membranes. Cyanosis becomes
apparent when there is more than 5 g/dL of deoxyhemoglobin present in the blood. An average hemoglobin level in dogs is
approximately 13-17 g/dL, and in cats is approximately 10-14 g/dL. This means the oxygen saturation of hemoglobin will be a
significantly decreased level on average of 61-70% for dogs and 50-64% for a cat before cyanosis is seen. Patients presenting with
cyanosis is severely compromised in their DO2 and requires immediate attention.
Oxygenation can be better gauged through measurement of PaO2, serving as an indicator of pulmonary function measured through
arterial blood gas analysis. A patient with normal respiratory function breathing room air will have a PaO2 of 80-100mmHg. PaO2 of
less than 80mmHg qualifies as hypoxemia, and less than 60mmHg is considered severe hypoxemia.
Pulse oximetry allows non-invasive measurements of the percentage of oxygenated functional hemoglobin in the arterial
bloodstream. The saturation of oxygen measured by pulse oximetry (SpO2) closely reflects SaO2 and can be used to estimate the
PaO2 level. The oxygen-hemoglobin dissociation curve expresses the relationship between SaO2 and PaO2. A SaO2 of 95-98%
corresponds to a PaO2 of 80-100mmHg. A SaO2 below 90% indicates a PaO2 of less than 60mmHg. Pulse oximetry has its
limitations, including false reading in the presence of significant levels of dysfunctional hemoglobin species (methemoglobin,
carboxyhemoglobin), inconsistent readings with movement, poor perfusion, anemia, and pigmented skin. Interpretation of
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oxygenation and pulmonary function can performed by calculated values called the PaO2:FiO2 Ratio (PF ratio) and alveolar-arterial
(A-a) gradient.
Carbon dioxide elimination
CO2 is a metabolic byproduct of energy production. The body normally maintains control of CO2 levels to control the pH level of the
body. An accumulation of CO2 causes an increase in levels of carbonic acid, increasing the levels of dissociated hydrogen ions,
resulting in an acidic environment. A reduction in CO2 level will lead to a decrease in hydrogen ions, leading to a more basic
environment. This effect is called respiratory acidosis and respiratory alkalosis, respectively.
The amount of CO2 eliminated by the body depends on the movement of air in and out of the alveoli to perform gas exchange, or
ventilation. Room air contains about 0.04% CO2 (0.3mmHg), and the replacement alveolar gas with fresh room air will promote
diffusion of CO2 out of the blood stream into the alveoli, which in turn gets expired out of the lungs and airway. A normal CO2 levels
within the blood is approximately 35-45mmHg in dogs, and 30-40mmHg in cats, and can be measured by blood gas analysis (PaCO2
if arterial or PvCO2 if venous). The difference in PCO2 in the pulmonary capillaries and alveoli create a pressure gradient required for
gas exchange (high to low; high in the capillary, low in the alveoli).
PCO2 is largely influenced by the amount of air that can be moved in and out of the alveoli, or alveolar ventilation. Reduced
ventilation leading to high PCO2 is called hypoventilation (>45mmHg) and occurs in cases of respiratory depression (suppression of
respiration due to drugs, neuromuscular disease, CNS disease), inability to expand the lungs (pleural space disease, compromise to
chest walls), or increased resistance to breathing (narrowed airway). Hyperventilation and subsequent low PaCO2 can be seen in
patients with increased RR due to anemia and hypoxia. In metabolic acidosis, compensatory increase in respiratory effort and
hyperventilation is often seen, countering the metabolic acidosis effect with respiratory alkalosis. This occurs because the presence of
hydrogen ions will stimulate the respiratory center of the brain to increase respiratory efforts.
The PaCO2 can be estimated by measurement of End-tidal CO2 (ETCO2). The CO2 content in the gas present at the probe at the
end of expiration is measured to obtain this value. The ETCO2 in normal cardiovascular and respiratory situation, is within 5mmHg of
the PaCO2. The ETCO2 is most easily measured when an endotracheal tube is placed in a patient (anesthetic procedure or
mechanically ventilated patients, for example). There are nasal tubes and masks available allowing for less invasive ETCO2
measurement.
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Place that Lifeline!
Advanced Vascular Access
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
Vascular access is a critical element in providing treatment for patients presenting in an emergency and requiring continued care
during hospitalization. Fluid and blood product infusions, drug administration, and blood sampling are a few key functions different
methods in vascular access can serve. Placement of short term peripheral catheters are commonplace in veterinary care even outside of
emergency and critical care. There are additional methods in providing vascular access such as central venous catheter placement,
intraosseous catheterization, and arterial catheterization, each presenting their own advantages and disadvantages while serving their
purpose.
Peripheral venous catheters
Peripheral catheterization is commonly performed in everyday veterinary practice, whether it is to administer IV fluids or an avenue
for IV injections used for induction of anesthesia. Any catheter that is placed in the periphery that is too short to reach a central vessel
is considered a peripheral catheter. Some of the major advantages to using a peripheral catheter includes the ease of placement,
minimal discomfort to the patient, and the inexpensive nature of the catheters themselves. In addition, they can be placed quite rapidly
with relatively minimal restraint, reducing the stress on the patient. In comparison to central venous catheters, peripheral catheters are
less likely to cause complications such as hemorrhaging, thrombosis, and catheter induced infections.
Commonly used location of insertion are the cephalic vein, saphenous vein, and more rarely, pedal, auricular, and jugular veins.
There is a common misunderstanding that a jugular catheter is by default a central line, though this is not necessarily true since
whether a catheter is considered central or not is based on the position of the tip of the catheter. The cephalic vein is catheterized with
ease in most patients, as the vein is easily visualized and remains straight for the length of the limb. There are, of course patients with
short limbs making catheterization difficult, but this is likely true for all other sites available on such a patient. The saphenous vein can
be an alternative catheterization location, though catheters placed in this location are more prone to occlusion through patient
positioning. Pedal veins are viable options for larger dogs, though the degree of discomfort seems to be greater. Auricular veins can be
more accessible for patients with short limbs, though stabilizing the catheter after placement is often a challenge.
Peripheral catheters are most often placed percutaneously with the vein visualized and/or palpated for the location. In cases of the
skin seemingly too tough for dry or smooth insertion, or if fraying of the catheter has occurred, creating a relief hole with a separate
needle and placing the catheter through the hole is appropriate. In some emergency situations, the vein may not be visible or palpable,
in which case a cutdown can be opted to be performed. A venous cutdown involves creating an incision over the anatomic location of
the vessel to visualize the vein directly. When a catheter is placed through cutdown, suturing of the incision as well as bandaging of
the catheter site is necessary.
While a simple task that is routinely performed, there are several complications associated peripheral venous catheters. The first of
which is phlebitis, or the inflammation of the vascular walls, causing inflammation of the vessel and surrounding tissues. A patient
suffering from phlebitis will show redness, swelling, and pain on palpation. Phlebitis can be caused by mechanical damage if the
catheter moves around, infection through the insertion site, or through irritation from injection of hyperosmolar fluids (high
concentration dextrose, propylene glycol based drugs, etc). When evidence of phlebitis is seen, the catheter is recommended to be
replaced in a different location. Thrombosis, or formation of clots, around the catheter insertion site can also occur, which impedes
normal blood flow. Another common complication is subcutaneous fluid infiltration which occur due to the catheter being outside of
the vein, leading to infusion of fluid under the skin. This could be from improper placement of the catheter to begin with, or the
catheter pulling out of the vein with skin movement. Infection of the catheter insertion site can also occur. Lastly, catheter embolism,
or fragmentation of the catheter and subsequent embolism can occur either from a faulty catheter, catheter damage from the stylette, or
accidental cutting when the tape is being cut.
Because these complications can occur, regular maintenance of the catheter insertion site is warranted. A typical protocol calls for
inspection of the insertion site every 24-48 hours, and whenever complications are suspected. Whenever a complication is suspected,
the catheter should be replaced. Routine replacement of IV catheters after 72-96 hours has not been shown to be beneficial in
preventing phlebitis or catheter induced blood stream infections, and replacement should be based on clinical signs of complications.
Central venous catheters
In contrast to peripheral venous catheters, central venous catheters have their most distal end terminate in a central vessel within the
chest cavity (cranial or caudal vena cava). Central venous catheters can be inserted through the jugular vein, or be inserted
peripherally through the saphenous vein (given you have the correct length catheter to reach the vena cava).
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Central venous catheters are preferred over peripheral venous catheters when the patient requires infusion of highly osmolar fluid
(high concentration dextrose, parenteral nutrition solution, for example), or infusion of multiple incompatible fluids are desired (a
multi-lumen catheter will be used in this case). Additional function of central venous catheters include measurement of central venous
pressure, sampling of central venous blood tests, serving as a sampling catheter, long term venous access, and prevention of
contamination by substances that can commonly contaminate peripheral catheters (vomitus, diarrhea, drainage/discharge).
Various types of central venous catheters exist. They may be through-the-needle or over-the-needle, and single-lumen or multilumen. In general, over-the-needle catheters are preferred as there is no hardware left on the catheter assembly that requires
maneuvering during the wrapping. Multi-lumen catheters are generally preferred over single-lumen catheters as it adds flexibility in
fluid administration, giving the ability to infuse multiple solutions simultaneously without worries of incompatibility. If the effort and
discomfort to the patient in placing a central venous catheter is already being made, giving ourselves the option of utilizing a multilumen catheter is a sound decision, as the patient is likely to require multiple infusions, and the cost between a single-lumen and multilumen catheter is small.
A commonly used technique in the placement of a central venous catheter is called the Seldinger Technique, or the guidewire
technique. A typical protocol and steps involved in the placement of a central line is provided (Figure 1). The Seldinger technique is
advantageous because it allows for a smaller catheter to serve as the introducing catheter, making placement in smaller patients or
hypovolemic patients easier. In addition, the guidewire can be utilized when a catheter needs to be replaced by refeeding a sterile
guidewire through the catheter, allowing a new catheter to be guided back into the vessel.
Similar complications to those in peripheral venous catheters can occur with central venous catheters. Due to its invasiveness, the
catheter is more prone to blood stream infections, and an appropriate maintenance protocol (examination of insertion site once every
24-48 hours) is required.
Intraosseous catheterization
Intraosseous (IO) catheters, are needles or cannulas inserted into the bone marrow. The marrow vessels, unlike peripheral vessels, do
not collapse due to the protective osseous coating it has as a part of the structure of the bone marrow. This makes the bone marrow an
effective avenue for fluid and drug administration even during circulatory collapse. The effectiveness of blood components and
crystalloids is equal to central or peripheral venous access. Some drugs and fluids may have a higher duration of action and peak
effect when given IO during shock, though onset of peak effect may be slower without pressurized infusion.
When IV access is difficult or taking longer than a few minutes, an IO catheter should be considered, and included as a part of a
standard fluid resuscitation protocol. An IO catheter is often placed in under a minute, at a very high success rate. Once an IO catheter
is placed and fluids given to provide better vascular volume, another attempt at IV access should be more likely to be successful.
Other situations which make IV access extremely difficult, such as peripheral edema, obesity, status epilepticus, and generalized burns
may be other indications for IO access.
Blood values obtained from IO catheters are found to be comparable to central or peripheral venous samples, aside from
potassium, glucose, and acid/base values.
IO catheter placement is contraindicated when fractures are present in the bone. This, along with previous IO catheter placement in
the same bone, can lead to extravasation of infusions. In the case of previous IO catheterization, a larger size needle may be inserted in
the same hole effectively plugging the existing catheterization site. Use of a completely different bone is also a solution. Placement of
IO catheters through infected tissue, or in pneumatic bone in avian species should be avoided.
Any sterile needle long enough and sturdy enough to bore through the cortex and easily contained by the marrow of a specific
patient is suitable. 18-22ga needles are often used for rodents, neonates, and even adult cats, small breed dogs. Bone biopsy needles
are used in adult cats and dogs. IO catheter drills and catheter guns are contraptions to aid IO placement.
Considerations to make regarding the catheterization site include ease of access and placement, possibility of interference in
procedures, and patient comfort (though not a major concern during an emergency situation). No site is shown to be better than the
other in terms of efficacy of infusions. The viable sites are (1) Tibia – Medial surface of proximal tibia, tibial tuberosity (point slightly
distally to avoid growth plate, which is a major longitudinal growth front for the tibia) (2)Femur – Trochanteric fossa (3) Humerus –
Greater tubercle (4) Hips – Wing of ilium, ischium. Any angle of insertion is acceptable as long as the needle tip is within the marrow,
though certain angles of approach may be easier for different sites.
Advancing the needle through subcutaneous tissue and periosteum may be painful. In stable patients, subcutaneous lidocaine block
may be used to attempt to prevent pain. Many patients requiring immediate IV/IO access will likely have altered mentation preventing
them from feeling or responding to pain. In these situations, the speed of placement will be prioritized over initial pain control.
The pressure build up when an infusion is started is known to cause pain in people. The same is assumed for non-human species.
Removing a small amount of marrow, and infusing lidocaine over a minute or so will help alleviate this initial pain. Once again, this is
likely not our primary concern in cases where seconds to minutes matter in the resuscitation of the patient.
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Chances of complications with IO catheters are low, but present. Infection are rare, especially when the catheter is removed as
soon as it is unnecessary. Extravasation of fluids, compartment syndrome (pressure buildup damaging muscle, nerve, blood vessels),
bone fracture, and fat embolism (unknown clinical significance) are among other complications that might arise.
Figure 1: Central venous catheter placement
Central line placement
Equipment needed
 Guide-wire catheter kit
 Suture
 Needle Holder
 Thumb forceps
 Clippers
 Surgical scrub
 Sterile gloves
 Drape
 #11 blade or large needle
 Sterile gauze
 Heparinized saline flushes
 Bandage material
 X-ray request
Preparation
 Determine if sedation is required, and administer prior to gathering of supplies to allow time. If transdermal analgesic cream
is to be used, clip and apply first.
 Clip area over the jugular, 2-4 inches by 2-4 inches depending on patient size.
 Pre-measure the distance from the intended insertion site to the 4th intercostal space.
 Aseptically prep the area in a circular, surgical scrub motion.
Procedure
1. Wash hands and don sterile gloves.
2. Drape the prepared area.
3. Place the over-the-needle catheter included in the kit into the vein, oriented towards the heart. (Note: in some cases, you will
not see a flash in your stylet hub, in which case check with syringe)
4. Insert the guidewire into the catheter and feed forward to the premeasured length.
5. Remove the catheter over the guidewire, taking care to not contaminate the guidewire.
6. Place the plastic dilator over the guidewire, and insert into the vessel through the skin. Tenting the skin, spinning the dilator,
and creating a relief hole will help facilitate the dilation process.
7. Remove the dilator over the guidewire after leaving in the vessel for a few seconds.
8. Place the catheter over the guidewire and feed into the dilated opening into the vessel. Be sure to observe the guidewire
exiting out the catheter port and hold it in place to prevent loss of the wire.
9. Once the catheter is fed to the pre-measured length, remove the guidewire.
10. Aspirate port with a syringe to confirm blood flow, then flush with heparinized saline. Attach needleless ports. Repeat for
each port to confirm patency. (Note: Aspirating first prevent injection of air).
11. Secure the catheter with suture using the suture wing(s).
12. Cover the insertion site with non-stick gauze pad or adhesive dressing, and bandage.
Placement procedures
After the site is chosen:
1. The hair on the potential insertion site should be clipped and the area disinfected. Be mindful of the balance of the time you
have versus the time it takes for a thorough scrubbing.
2. A stab incision can be made to allow for easier access to the insertion site.
3. Firm and steady pressure should be applied to the bone with an alternating clockwise and counterclockwise rotation (being
careful not to slip on the bone surface).
4. Once the initial hole is started with the needle, the pressure can be increased as the same motion is made, to bore faster
through the cortex.
5. When the needle pushes through the cortex, a sudden loss of resistance will be felt.
6. Proper placement of the catheter can be confirmed in a few ways:
a. Firmness of the catheter insertion – There will be very little wiggle in the needle when properly inserted through
cortex.
b. Movement with the limb – Catheters in the cortex will make the same movement as the bone it is inserted in. If the
catheter moves independently of the bone, or vice versa, the catheter is likely placed improperly.
c. Aspiration – Bone marrow should be able to be aspirated in a properly placed catheter, though this is less likely to
occur in an older animal.
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d.
7.
8.
Saline Infusion – If placed correctly, saline should be able to be pushed without much resistance. If a large
backpressure is encountered, the needle is likely to be in the cortex, or pushed against it. Rotation of the needle
90-180 degrees may alleviate this if the needle opening is simply pushed up against cortex. If the infusion results
in subcutaneous elevation of tissue (subcutaneous “bleb”), the catheter is improperly placed.
Once proper placement is confirmed, the catheter is stabilized via tape or suture on tape wings. Some IO catheters will come
with suture wings.
Proper catheter care is required with bandages applied when possible. A properly maintained IO catheter may be kept for
72hours with minimal chance of complications. Typically, IO catheters are replaced by IV catheters within 2-12 hours after
initial fluid resuscitation.
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Shock Has Two Faces:
The Keys to Perfusion
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
Shock has two faces. Shock is defined as an inadequate production of cellular energy, very commonly brought on through forms of
circulatory failure. Hypovolemic (inadequate circulating blood volume), cardiogenic (inability for heart to create forward flow),
distributive (loss of systemic vascular resistance), and obstructive (obstruction of large vessels, sometimes not considered its own
category) shock describe one aspect of inadequate delivery of oxygen (DO2) leading to inadequate production of cellular energy.
Shock despite proper circulatory function arises from metabolic dysfunction due to inadequate substrate supply or dysfunctional
metabolic mechanisms. Oxygen is a very important component in carrying out aerobic metabolism, a vastly more efficient and
sustainable method of energy production than anaerobic metabolism which takes place with the absence of oxygen. Lack of oxygen
being delivered to tissues from inadequate oxygen content in arterial blood lead to what is known as hypoxemic shock, and may occur
from varying reasons.
Oxygen in energy production
The importance of maintaining adequate DO2 lies in the difference of the amount of adenosine triphosphate (ATP) produced in the
presence and absence of oxygen. ATP is considered the “currency of cellular energy”, providing energy for cellular processes required
to maintain life as phosphate groups are cleaved off resulting energy release and formation of adenosine diphosphate (ADP) or
adenosine monophosphate (AMP). ATP is involved in cellular signaling, DNA and RNA synthesis, muscle contraction, cytoskeletal
maintenance, active transporting, and many other cellular functions. There is a finite amount of ATP available within a body, and a
constant recycling of ADP and AMP into ATP is required to keep up with energy demands. In the presence of oxygen, 38 ATP
molecules are generated from metabolism of a single glucose molecule undergoing oxidative phosphorylation occurring in the
mitochondria. In contrast, a single glucose molecule yields two ATP molecules through anaerobic metabolism. The presence of
oxygen is imperative in efficient energy generation.
Provided there is adequate functional hemoglobin levels and normal respiratory function, DO2 is dependent on the ability to
circulate the oxygen containing blood to tissues requiring oxygen, called perfusion. The mathematical expression of DO2 is: DO2 =
CaO2 x CO. Oxygen contained within blood exists in two forms; dissolved in the plasma and bound to hemoglobin. The amount of
oxygen dissolved in plasma depends on the partial pressure of oxygen (PaO2), with 1 mmHg creating enough tension to result in
0.0031mL of dissolved O2 per dL of plasma. Each gram of hemoglobin is able to theoretically carry 1.39mL of O2 when fully bound
with oxygen, making up a significant portion of oxygen content of blood. In reality, there are portions of dysfunctional hemoglobin
lowering this to approximately 1.34mL. In addition not every hemoglobin molecule will be fully bound to oxygen in every situation
(SaO2, or arterial oxyhemoglobin saturation) adding some variability. With all of these considerations in mind, the resultant formula to
quantify DO2 is the following, expressing the impact lowered hemoglobin concentration and saturation of the hemoglobin will have on
overall delivery of oxygen: DO2 = [(1.34 x Hgb x SaO2) + (0.0031 x PaO2)] x CO.
In animals without disease, DO2 is significantly above oxygen consumption (VO2), supplying a very comfortable buffer of
available oxygen for energy production. This buffer allows for sudden changes in oxygen demand through changes in cellular
metabolic rate or reduction in CaO2. When DO2 is significantly compromised (termed critical oxygen delivery), tissue hypoxia results
and increased lactate levels and lowered pH are seen. The oxygen extraction ratio can also be used to express the level of oxygen
consumed in relation to DO2 (O2ER = VO2/DO2). Higher oxygen consumption or lower DO2 leads to a higher ratio. The normal O2ER
value is approximately 0.2, though different organ systems have varying O2ER (normal O2ER of the heart is 0.6, making it more
sensitive to hypoxemia). A normal DO2, VO2, and O2ER in dogs were observed to be 790ml/min/m2, 164ml/min/m2, and 0.205,
respectively in one study. Another couple of studies cite a normal DO2 of 20-25ml/kg/min and observed critical oxygen delivery levels
of 8-11ml/kg/min regardless of the cause (anemia, hypoxemia, and cardiac tamponade). A patient is said to be in hypoxemic shock
when Hgb, SaO2, or PaO2 levels are low enough for DO2 to reach this critical oxygen delivery level. In clinical settings, measurement
of specific values such as CO and VO2 (though can be estimated) are rather difficult, and we utilize this concept in determining when
a patient is suspected to be in hypoxemic shock rather than making direct comparisons.
Tissue perfusion
The maintenance of normal blood pressure and tissue perfusion depends on adequate CO, and systemic vascular resistance (SVR). The
most common form of reduced DO2 and shock occurs secondary to reduction in CO or SVR. CO is can be reduced through a loss of
intravascular volume, leading to hypovolemic shock. Hypovolemic shock can be caused by many situations leading to hypovolemia,
such as internal or external hemorrhaging, fluid loss through vomiting, diarrhea, polyuria, exposed subcutaneous surfaces (burns, bit
wounds) and/or reduced water intake. A loss in circulating blood volume leads to a diminished venous return and preload to the heart,
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reducing the stroke volume (SV). A significant degree of reduced CO due to decreased SV is compensated for through an increase in
heart rate (CO = SV x HR). SV itself is improved through increased contractility, or a more forceful contraction of the heart to eject a
larger volume of blood. Reduced blood flow to the kidneys stimulates the renin-angiotensin-aldosterone system, increasing
production of aldosterone leading to sodium retention, increasing plasma osmolarity and encouraging shifting of fluid to the
intravascular compartment. Increased antidiuretic hormone (vasopressin) also promotes water retention, reducing urinary fluid loss.
While vasoconstriction does not directly add to intravascular volume, its occurrence increases systemic vascular resistance, improving
blood pressure and circulation of the reduce blood volume.
Patients faced with hypovolemia initially show signs of compensatory shock, involving tachycardia, normal prolonged capillary
refill time (CRT), normal to pale mucous membranes, tachypnea, and cool extremities. Pulse quality and blood pressure may be
mostly normal, and subtle depression in mentation may be seen. As intravascular volume continues to be lost, compensatory
mechanisms will be unable to adequately maintain proper perfusion, and later signs of shock such as pale mucous membrane,
prolonged CRT, poor pulse quality, depressed mentation, and hypotension will be seen. Uncorrected poor perfusion will lead to organ
ischemia, leading to organ failure and death.
CO can be significantly affected by cardiac dysfunction as well. Congestive heart failure from cardiomyopathy can reduce
contractility of the heart or reduce end-diastolic volume, decreasing SV and subsequently, CO. Cardiac arrhythmias may lead to
improper filling, ejection, and effectiveness of the heart to create CO. Cardiac tamponade, occurring when effusion fills the pericardial
space creating external pressure on the myocardium significant SV. Certain drugs may have cardiovascular depressant effects or cause
myocardial conduction defects, leading to reduced CO. Any cardiogenic cause leading to reduced CO and resultant shock is called
cardiogenic shock.
Distributive shock is another form of shock characterized by an inappropriate distribution of blood flow and volume. One example
can be considered vasodilatory shock, resulting in profound vasodilation causing “relative hypovolemia” and a reduction in SVR,
leading to reduced BP and poor perfusion. Systemic inflammatory response syndrome (SIRS) and septic shock (SIRS due to an
infectious cause) involves vasodilation caused by cytokine and other inflammatory mediator secretion leading to a hyperdynamic
phase involving hyperemic mucous membranes, bounding pulses, fever, and tachycardia. As the hypoperfused state is allowed to
persist, myocardial damage leads to reduced cardiac output, and clinical changes to the patient to more classic signs of shock.
Tachycardia, pale mucous membranes, prolonged CRT, cold extremities, poor pulse quality, and depressed mentation will be signs of
significantly impaired perfusion.
Patients suffering from gastric dilatation-volvulus (GDV) will have a distended stomach compressing the intra-abdominal vessels
(caudal vena cava, portal veins, and splanchnic vessels), impeding venous return to the heart leading to a reduced CO. This is
considered obstructive shock by many (while many others consider it a form of distributive shock), where major blood vessels are
occluded or carry reduced blood flow contributing to poor CO. The cause of shock in GDV is actually muti-faceted, since the
occlusion of major vessels leads to portal hypertension and splanchnic pooling, leading to effusion of intravascular fluid into the
abdominal cavity and interstitium, contributing to hypovolemia. Additional fluid loss may also occur due to vascular injury to gastric
vessels as it is stretched, and repeated vomiting. Many disease processes involve different causes of shock occurring in varying in
degrees, leading to the cumulative effect of reduced CO and DO2.
Monitoring
The effectiveness of therapy can be determined through physical parameters as well as laboratory values. Physical perfusion
parameters consist of mentation, heart rate, pulse quality, mucous membrane color, CRT, core to extremity temperature gradient. A
patient in shock will have dulled mentation, increased heart rate (bradycardic in decompensated shock), poor pulse quality, pale
mucous membrane (hyperemic if early vasodilatory shock), prolonged CRT, and a significant difference in core vs extremity
temperature. These physical parameters should be monitored as shock is treated to ensure signs of poor perfusion are alleviated as
therapy is continued. Except during compensatory shock, hypotension would be present and thus blood pressure should be monitored
for changes. If hypotensive, initiation of therapy should be aimed to increase to a normal ranges (MAP 70-120mmHg). Blood pressure
may be measured indirectly via Doppler, oscillometric monitors, or directly through an arterial catheter and pressure transducer setup.
Hypoperfusion of tissues and inadequate oxygen delivery results in anaerobic respiration. Anaerobic respiration is performed in
hypoxic situations, leading to hyperlactatemia, and resultant metabolic acidosis. Normal lactate level dogs and cats is 0.5-2.0 mmol/L.
Elevated lactate measurement indicates significant lactate production overwhelming the liver’s metabolic clearance rate. Serial lactate
measurements as fluid resuscitation is performed will allow monitoring of changes in the lactate level. A swift decrease in lactate level
during fluid resuscitation serves as a positive prognostic indicator in patients with shock.
Other assessment tools such as central venous pressure may help guide fluid therapy and monitor fluid balance in a patient as fluid
therapy is continued. Mixed venous oxygen saturation (SvO2), or oxygen saturation of hemoglobin at the pulmonary artery (after
maximal oxygen extraction), will be decreased when DO2 is decreased. Since pulmonary arterial catheters are not commonly placed in
veterinary medicine, central venous oxygen saturation (ScvO2) can be used as an indicator for SvO2, as the values parallel each other
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closely, and a reduced ScvO2 typically correlates to a reduced SvO2. Urine output serves as an indicator for adequate renal perfusion,
and will be greater than 1ml/kg/hr when blood flow is adequate. Urinary catheters are placed in critical care patients for the purpose of
urine output monitoring. In the absence of renal disease, urine specific gravity may give clues as to adequate fluid infusion rate as
well. Cardiac output itself can be monitored through advanced modalities such as thermodilution or lithium measurement, though not
readily available in veterinary medicine.
Therapy
Treatment for shock will vary depending on the underlying cause. Hemorrhaging may require surgical intervention, or treatment of
coagulopathies. Treatment of sepsis is a very intensive process including early antimicrobial administration. Cardiomyopathies may
require various anti-arrhythmics, anti-hypertensives, or inotropics. These are only a few examples. Regardless of the underlying cause,
there is a general strategy that can be applied to treating patients in shock which is aimed at reversing the restoration of tissue
perfusion and preventing progression of shock while the underlying causes are treated.
Obtaining vascular access is one of the first steps in restoring cardiovascular stability in states of shock. A larger diameter, shorter
catheter will cause the least amount of resistance for fluid boluses to be administered and recommended. Many of these patients,
however, will have a compromised cardiovascular system often making placement of intravenous catheters difficult. Placement of a
jugular venous catheter or intraosseous catheters may be more readily possible compared to placement of peripheral venous catheters
and should be considered very early in attempting vascular access.
The first line of therapy is isotonic crystalloid therapy in all forms of shock aside from shock arising from cardiomyopathies
(adding intravascular volume in congestive heart failure will exacerbate the congestion). A IV crystalloid bolus dose of 20ml/kg may
be given, and the patient re-evaluated for further need. Crystalloids are thought to remain in the intravascular space only for a short
amount of time (25% remaining approximately 30 minutes after infusion), and may require re-dosing at this point. In the case of
hemorrhaging, hypotensive resuscitation, keeping the MAP approximately 60mmHg, may be beneficial in preventing exacerbation of
bleeding. Infusion of crystalloids is aimed at replacing lost intravascular volume, or adding intravascular volume to combat relative
hypovolemia caused by vasodilation.
Synthetic colloids such as hetastarch and tetrastarch provide higher osmolarity than crystalloids, allowing better retention and even
causing shifting of fluid into the intravascular space, increasing intravascular volume and better tissue perfusion. In human medicine,
there was recently a warning issued regarding the use of hetastarch and it being linked to renal injury. While human kidneys and
canine/feline kidneys seem different in terms of sensitivity to insult, hetastarch is now recommended to be used with caution. Natural
colloids are available in the form of albumin contained in plasma or albumin concentrate. Plasma may be used to supplement albumin
levels in hypoalbuminemia. Hypoalbuminemia may result due to protein losing enteropathy or nephropathy, septic peritonitis, trauma,
burns, and any other pathologies causing protein loss. However, the dose required for this particular use is 20-25mL/kg to achieve an
increase of 0.5g/dL in plasma albumin. For example, a 25kg patient with an albumin level of 1.0g/dL will require 1000-1250mL of
plasma to regain a low normal plasma albumin level of 2.0g/dL. In addition, this is not taking into account ongoing loss from the
patient’s pathology. Use of plasma in this manner will pose a higher transfusion related complication risk, be an inefficient use of
plasma, and will be at a significant cost to the owners. Serum albumin concentrate is a better source of albumin.
Human serum albumin (HSA) has been used in canine patients with hypoalbuminemia. However, these infusions have a significant
chance of an immunologic reaction as human albumin differs from canine albumin by 20% of its amino acid sequence. Previous
sensitization to human albumin and subsequent acute hypersensitivity reactions are especially a concern when repeat doses are
necessary. A study found presence of anti-albumin antibodies in dogs without prior exposure to human serum albumin, which was
hypothesized to be from prior vaccinations involving production in bovine albumin cultures. Canine specific albumin has recently
been produced as a commercial product, observed to increase serum albumin levels in the recipients with a low chance of
immunologic complications. The most recent published study indicated albumin administration in dogs with septic peritonitis to have
improved albumin level, Doppler blood pressure values, and colloid osmotic pressure measurements, as well as a comment on the
association between albumin transfusion and survival. A connection between an improvement in serum albumin level and ultimate
survival continues to be a topic under investigation,
Hypertonic saline (7% compared to 0.9% in normal saline) possesses higher osmolarity than crystalloids, which provides a
hyperosmolar shifting of fluids into the intravascular space upon injection. The effect of hypertonic saline has a fast onset though the
effect is also short lived. There may be additional beneficial effects such as reduced endothelial swelling, modulation of inflammation,
and increased cardiac contractility. A mixture of hypertonic saline and synthetic colloids given simultaneously has been seen to
improve hemodynamic status better than each given individually. Blood products such as pRBC and plasma may need to be
administered in cases of severe hemorrhaging or coagulopathy. Blood products are not recommended to be used solely as volume
replacement due to potential immunologic and non-immunologic complications. RBCs are warranted for existing or anticipation of
clinically significant anemia due to the rate of hemorrhaging seen. Plasma is useful in replacing coagulation factors. Hemoglobin
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based oxygen carrying solutions such as Oxyglobin, if available, will allow replacement of oxygen carrying capacity as well as
providing colloidal effects without risk of immunologic complications.
When efforts in providing better intravascular volume are not sufficient in restoring adequate perfusion, vasopressor and inotropic
therapy is required. Vasopressors function to provide vasoconstriction improving perfusion by increasing SVR. Vasopressors such as
dopamine, norepinephrine, phenylephrine, epinephrine, and vasopressin may commonly be used. Inotropes such as dobutamine
improve cardiac output through increasing myocardial contractility.
As with many conditions, successful treatment of shock depends on early recognition, assessment, and swift response and
treatment of shock. Quick determination of the cause of impaired perfusion will allow for the appropriate fluid resuscitation strategy
and medical management. Technicians play a large role in providing the monitoring of the patient as therapy is performed, through
frequent monitoring of physical perfusion parameters and working in conjunction with the veterinarian to provide additional measures.
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The Bloody Truths:
Myths and Facts of Transfusion Medicine
Kenichiro Yagi, BS, RVT, VTS (ECC, SAIM)
Adobe Animal Hospital
Los Altos, CA
Despite the increase in use of blood products and transfusion therapy becoming more commonplace, there are many questions
surrounding their use. Many of these questions are being answered by a combination of emerging veterinary and human evidence
further clarifying already known concepts, with others confirming long time suspicions and teaching us something new.
Can RBCs be given through an infusion pump?
Whether there is an optimal method of red blood cell transfusion administration has been a point of discussion. Recommendations
from infusion pump manufacturers are variable in ability to transfuse blood products. The criteria used to make these
recommendations are also uncertain without an established standard or regulatory body in validating these claims. An ideal method of
administration should allow one to administer the red cells at a consistent and specified rate while not affecting the integrity, survival
time, and oxygen carrying capacity of the red blood cells.
Studies evaluating the effect of various administration methods on the integrity of blood cells exist. The majority of these studies
investigate the in vitro effect of infusion pumps, measuring the degree of free RBC content (free hemoglobin, potassium, lactate
dehydrogenase, bilirubin) and osmotic fragility. The results vary from observing significant increases to insignificant increase in
values, while transfusions with red cells with longer storage time resulting in a larger increase of hemolysis markers than those with
shorter storage times. The variability in results, in addition to the anecdotal evidence of patients benefiting from RBC transfusions
administered with infusion pumps are a cause for varying opinions.
A study assessing in vivo survival time of RBCs infused with various infusion methods, compared the use of gravity flow,
volumetric peristaltic pump, and syringe pump in autologous transfusions in dogs. Blood was collected from 9 healthy dogs, washed,
and separated into 3 portions labeled with different densities of biotin. These labeled red cells were transfused through either gravity
flow with a 170-260 µm filter, volumetric peristaltic infusion pump with a 170-260 µm filter, or a syringe infusion pump with an 18
µm aggregate filter at 2mL/kg/hr. Blood was sampled from test subjects at day 1, and every 7 days until day 49, measuring the
proportion of red cells with biotin labels through flow cytometry. Additional in vitro testing was conducted, measuring plasma
hemoglobin and osmotic fragility testing.
Labeled RBCs infused through gravity flow, volumetric pump, and syringe pump were detectable in 100% (8/8), 50% (4/8), and
14.3% (1/7) samples, respectively post-transfusion. The quantity and half-life between RBCs infused by gravity flow and volumetric
pump that were detectable (4/8) were not different. The RBCs infused via syringe pump detected at 24 hours post transfusion was no
longer detectable at 7 days, indicating complete removal of those cells from circulation sometime between 24 hours and 7 days post
transfusion. There were no differences seen in in vitro values examined.
The study concluded that delivery of RBCs with a syringe pump and microaggregate filter is associated with significant decrease in
in vivo survival time. Volumetric pump delivery was associated with a 50% probability of loss of transfused RBCs within the first 24
hours, and gravity flow allowed for highest chance of RBC survival. The reason behind this difference is speculated to be the
mechanical shear damage to the RBC membranes when transfused through the microaggregate filter, causing preferential removal of
damaged cells upon entry into the circulation and exposure to the mononuclear phagocytic system. Though unconfirmed, there is a
potential for microclots to have formed in the blood during resuspension in sub-room temperature plasma, which placed a higher
degree of shearing stress on the RBCs going through the filter, causing this effect. Early denaturation and oxidation of hemoglobin due
to the mechanical stress induced by syringe pump and volumetric pump methods, leading to IgG binding to the red cell surface and
removal from circulation, is another possible cause for early removal
There were other limitations to this study such as the reduced half-life of transfused RBCs when compared to our current
knowledge of dog erythrocyte lifespan (43 days in study vs 104-110d) attributed to the insult to RBCs during the biotinylation and
processing. The use of biotin for RBC detection itself is not without worries of immunologic removal through anti-biotin antibody
production, though previous studies have observed no development of such antibodies. Small sample sizes limiting the power of the
results is a common limitation in the veterinary field, and this study is no exception. The results are most relevant to exact methods
used in the study, and we can only make speculations on alternate setups to remove the use of microaggregate filters with the syringe
pump (use of an in-line pediatric 170-260 µm filter or extraction of blood through a 170-260 µm filter administration set into a
syringe, for example).
The authors of the study recommended against using a syringe pump with 18 µm aggregate filters in the light of the results of their
study, though considering the limitations, drastic changes to clinical protocols was not stated to be necessary. The current best practice
considering this evidence would be to administer blood products via gravity flow for larger volume, higher flow rate transfusions as
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long as consistency in flow rate is monitored closely (as it can be influenced by catheter patency, positioning and motion by the
patient, and amount of blood left in the bag). The syringe pump method is particularly useful when performing small volume
transfusions such as in felines. A similar study performed with feline blood stated their observation of RBC survival time being
unaffected by the syringe pump method.
PRBC has an expiration date of 42 days(?)
Current practices in blood banking involve the usage of APS and additive nutrient solution which are labeled for 42 days of storage.
More recent evidence gathered over the past decade indicates stored red blood cells to have impaired RBC survival, reduced efficacy
as an oxygen carrier, and even incite adverse effects in the recipient causing mortality and morbidity. These changes are seen as early
as 7 to 14 days into storage, and involve a collection of biochemical, biomechanical, and oxidative changes to the RBC and storage
solution, all collectively referred to as “storage lesions”.
Mature RBCs lack mitochondria and rely on glycolysis for ATP production, leading to a lowered pH. ATP production is reduced
by the acidic environment, combined with depletion, leads to decreased RBC membrane integrity. Lowered pH also affects 2,3
diphosphoglycerate (2,3 DPG) level reducing hemoglobin’s effectiveness as oxygen carriers, though this effect is reversible and not
significant in cats. Hemoglobin in longer stored RBC products contain free hemoglobin and microparticles that scavenge nitrous oxide
(NO) upon transfusion and cause a vasoconstrictive effect impairing blood flow, stimulate coagulation, induce oxidative damage, and
cause proinflammatory effects. Microparticles, which are vesicles that have budded off of cellular components, induce
proinflammatory and procoagulant effects. Stored RBCs show morphologic changes to echinocytes and spheroechinocytes leading to
a loss of deformability and impairment in normal flow through capillaries. Oxidative damage leads to increased hemolysis and
methemoglobin formation decreasing viable RBC count and oxygen carrying capacity.
There are many complicated mechanisms in play during RBC storage. To summarize the effects, storages lesions can lead to
impaired RBC survival, reduce the efficacy of RBCs as oxygen carriers, and induce adverse effects such as arrhythmias, thrombosis,
systemic inflammation, transfusion-related acute lung injury (TRALI), acute respiratory distress syndrome (ARDS), hypotension, and
multiple organ dysfunctions. These changes occur as early as 7-14 days into storage, making supplying our patients with safe
transfusion products a realistic challenge. Clinical impact of storage lesions is a topic of ongoing investigation while blood banks
strive to balance provision of fresher products and minimizing wasting.
First transfusions are “free”?
Compatibility testing for canine blood transfusions has traditionally been omitted in the interest of swift transfusions and financial
considerations. This comes from the a widespread notion that the “first transfusions are free for dogs”, intended to state that canine
RBC transfusions can be given without blood type matching (without typing the donor or recipient) or cross matching yet be
performed without signs of immunologic complications, namely acute hemolytic transfusion reactions or anaphylaxis. This statement
is made with the understanding that the most clinically significant dog erythrocyte antigen (DEA) is DEA 1, responsible for inciting
acute hemolytic transfusion reactions when preexisting alloantibodies for the antigen is present. In 98% of the population, these
antibodies are not present, so the first mismatched transfusion will only result in sensitization of the immune system to the antigen,
leading to the development of antibodies over a course of approximately 4 days. This leads to a delayed hemolytic transfusion
reaction, often asymptomatic as long as the patient has overcome the initial incident of anemia, or clinical symptoms of anemia as well
as bilirubinemia and bilirubinuria may arise.
Given the asymptomatic or mild nature of clinical signs, many have accepted this reason to forgo compatibility testing. However,
the sensitization will lead to an acute hemolytic transfusion reaction in subsequent mismatched transfusions, resulting in hemolysis of
transfused cells and likeliness of anaphylaxis. By omitting compatibility testing, we run the risk of priming a patient for such reaction
in the next transfusion which may be handled similarly if the patient’s transfusion status is not noticed. A medical team may be placed
in a situation where the transfusion status of the patient may be unknown (pet brought in by pet sitter who thinks there had been no
transfusions, or adopted dogs who “probably” has not had a transfusion). In the case a patient presents with risk of imminent death
from anemia, this practice may be justified with the knowledge of the risk. Blood typing of all blood donors and stocking of DEA 1
negative blood is highly recommended for use in these situations to avoid sensitization of the patient to DEA 1. If there is any
uncertainty in the transfusion history of the patient, cross matching is appropriate as erythrocyte antigens aside from DEA 1 exist with
limited knowledge on consequences from patients sensitized for these miscellaneous antigens (some reports of AHTR exist).
Transfusions of canine RBCs without compatibility testing are not “free”, and certainly have the hidden costs of DHTR and
sensitization. Cats possess alloantibodies for the RBC antigens foreign to them (aside from the very rare type AB cats), leading to
hemolytic transfusion reaction even with first exposure.
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DEA 1 negative is the universal blood type?
The concept of “universal” blood type indicates a blood type that can be given to any member of the same species without expectation
of an immunologic reaction related to blood type mismatches. Because DEA 1 is the one antigen we know most about and leads to
AHTR when mismatched for the second time, blood from DEA 1 negative dogs can be given without sensitization of DEA 1 negative
and DEA 1 positive recipients, and often is considered as “universal”. There are, however, other RBC antigens such as DEA 3 through
8, dal, and other less known antigens confirmed to exist which can lead to sensitization when mismatched transfusions occur.
Therefore, a donor should be tested negative for every RBC antigen we are capable of testing in order to truly considering it
“universal”. This creates a challenge as 98% of the canine population is positive for DEA 4, and a donor negative in DEA 4 is
virtually impossible to find. Fortunately this is not a clinical issue since the recipient is likely DEA 4 positive as well, allowing the
blood types to match. Another challenge lies in our current inability to routinely test for DEA other than 1, 4, and 7 through a
reference lab due to a lack of testing anti-sera (and anything aside from DEA 1 not available as in-house kits), preventing complete
typing of our donors and timely testing of our recipients. Given our knowledge of additional RBC antigens, we should consider DEA
1 negative, 4 positive, 7 negative blood type as the “least antigenic”, and type our donors for all DEAs we are capable of, given
finances permit it. DEA 1 negative can be considered safe blood to use from anecdotal evidence as reports of hemolytic transfusion
reactions are rare, and cross matches should detect incompatibility issues arising from repeated exposure to the less known erythrocyte
antigens. Cats have no universal donors, though type AB cats may receive transfusions from both type A and B donors.
Are blood transfusions between different species possible?
Common knowledge dictates that blood product transfusions should be between members of the same species in order to prevent
immunologic consequences. Despite this “common” fact, one may be surprised to hear an ongoing research to test interspecies
transfusions, or xenotransfusions. Early experiments in blood transfusion in the 1600’s document a human patient receiving sheep
blood, and showing no signs of reaction (at least on first exposure). Porcine red blood cells with modified antigens have been a topic
of research in compatibility as human blood substitute. In the veterinary field, feline blood is consistently in short supply, especially
for patients with the rare blood type of B. Type B cats can only be transfused with type B blood as introduction of a small volume of
type A blood will result in an acute hemolytic reaction and anaphylaxis. In addition, even for type A patients, blood supply may be
short causing delays or inability to obtain blood products in a timely manner as the patient suffers life-threatening anemia. In these
situations, veterinarians have attempted to use canine blood as a source of blood as it is more readily available, and can easily tolerate
the small volume donations.
There is limited amount of evidence available from a few studies conducted on canine to feline transfusions. The results of the
studies concluded felines do not possess naturally occurring alloantibodies against canine erythrocytes. Compatibility testing methods
such as slide-agglutination test and cross-matching only revealed agglutination on the minor-crossmatch. Of the total of 62
transfusions performed between the various studies, 5 cats showed signs of mild reactions, with tachypnea and pyrexia within 24
hours of the start of transfusion. Development of antibodies against canine RBCs were seen 4 to 7 days after the transfusion,
indicating the transfusion led to sensitization of the immune system to the foreign antigens. Because of this, the life span of the
transfused RBCs was approximately 4 days due to delayed hemolytic transfusion reactions while feline to feline transfusions allow
RBCs to last 30 days. Subsequent transfusions resulted in anaphylaxis and were fatal in 66% of documented cases.
While transfusion of dog blood to a feline patient is not the best solution to supplementing oxygen carrying capacity, it may be
justifiable when faced with imminent death of the feline patient and without blood. A responsible medical team would discourage dog
to cat transfusion and consider the method for situations where the patient 1) has no source of compatible cat blood (Type B cat with
no stocked blood, donor, or nearby hospital with stock, for example) or hemoglobin based oxygen carrier solutions, 2) is imminently
going to pass away without a transfusion or compatible blood will not be obtained soon enough (truly dying animal), 3) is expected to
benefit from a short term oxygen carrying capacity gain, and 4) the owner understands risks and consequences. The method of
xenotransfusion should not become a common practice and effort for practices to maintain a good source of cat blood should always
be pursued without considering canine blood as “backup”.
Premedicating reduce chances of reactions?
Premedication, or administration of antihistamines, glucocorticoids, or antipyretics in anticipation of immunologic complications to
counter histamine and inflammatory mediators and suppress the effects, have been a traditional practice in transfusion medicine.
While there is no veterinary evidence available addressing the efficacy of this practice, there are a number of human studies observing
no difference in incidence of type I hypersensitivity reactions (allergic reaction) or febrile non-hemolytic transfusion reactions
(FNHTR). Some clinicians reason that administration of premedication potentially masks early symptoms of immunologic
complications delaying required interventions for treatment, advocating against it. Evaluation of the difference in severity between
recipients with premedication or without premedication has not been performed, and remains a question whether this reasoning is
valid. Human evidence is unfortunately not always directly translatable into veterinary practice, though expectations of similar
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physiological mechanisms exist. Studies evaluating effects of premedication and efficacy in prevention of hemolytic transfusion
reactions are not apparently available, and the theoretical benefit is no justification for forgoing proper compatibility testing.
Is warming of blood products necessary?
Warming of blood products in the interest of prevention hypothermia in the recipient is a consideration during blood product
administration. Concerns for hemolysis of erythrocytes when warming during transfusion exist, and studies point towards little to no
difference in markers for hemolysis in vitro when blood is warmed to typical body temperature. However, at non-emergent
administration rates, blood reaching the patient through the line placed in a room temperature environment is easily at room
temperature upon reaching the patient, and will not contribute to a significant decrease in body temperature. In the case of rapid
transfusions of large volumes into small patients, warming of the blood may be indicated with care taken to be evenly warmed to 3537°C and not exceed 42°C close to the patient to minimize loss of heat. Hypothermia is also a documented complications related to
massive transfusions. Aside from these situations, in many cases warming effort directed at the patient is most effective in treating
hypothermia without causing risk of damage to the RBCs.
Is plasma indicated for use in hypoproteinemia? Parvoviral enteritis?
Plasma contains many proteins of interest, namely hemostatic proteins, albumin, and immunoglobulins. Hypoproteinemia, specifically
hypoalbuminemia, occurs in many critically ill patients with protein-losing disorders including protein-losing enteropathies, proteinlosing nephropathies, liver failure, trauma, burn wounds, etc. This leads to a loss of intravascular colloid osmotic pressure (COP), and
subsequent consequences. Administration of plasma products (fresh frozen plasma, frozen plasma, or cryosupernatant) have been used
as a method in supplementing albumin for COP. However, the amount of plasma required to raise the patient’s albumin level by 1g/dL
is approximately 40-50mL/kg. This is equivalent to 1.1L of plasma (9.5 units) for a 50# patient. The amount of plasma required to
make a significant difference in the measurable level of albumin is both cost prohibitive and pose a large immunologic risk to the
patient. Whether increasing the albumin level to a normal value (>2g/dL) will lead to increased chances of a positive outcome is still
unclear, and difficult to advocate.
Similar concepts can be applied to the usage of plasma products derived from survivors of parvovirus infection. Clinicians have
theorized that transfusion of plasma containing antibodies against canine parvovirus (CPV) will aid in recovery from CPV infections.
A study evaluating use of a single dose of plasma containing CPV antibodies in its efficacy versus saline placebo saw no significant
difference in reducing clinical signs, viremia, or speeding recovery. The volume used in this study (12mL) may be a limitation to the
efficacy of the compared treatment, though the amount of plasma required for an adequate dosage of antibodies is unknown, and is
likely to be at similar or higher levels of dosage for albumin supplementation. Thus, same concerns prevent use of plasma in this
manner.
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