Download first step program - Association of Exotic Mammal Veterinarians

FIRST STEP PROGRAM
International Conference on Exotics
Sponsored by the Association of Exotic Mammal Veterinarians
www.aemv.org
June 4, 2003
Teresa L. Lightfoot D.V.M. Diplomate ABVP – Avian
Florida Veterinary Specialists
3000 Busch Lake Blvd.
Tampa, FL USA 33614
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Table of Contents
Rabbits (Oryctolagus cuniculi) ................................................................................... 4
Physical Examination...................................................................................................... 5
Incisor removal ........................................................................................................... 5
Molar malocclusion .................................................................................................... 6
Analgesia / sedation ...................................................................................................... 10
Injections ....................................................................................................................... 10
Venipuncture ................................................................................................................. 11
Fluid administration ...................................................................................................... 11
Surgical considerations ................................................................................................. 12
Ovariohysterectomy .................................................................................................. 12
Post-operative Considerations .................................................................................. 14
Castration .................................................................................................................. 14
Gastrotomy................................................................................................................ 15
Common Disease Syndromes ....................................................................................... 17
Abscesses .................................................................................................................. 17
Epiphora .................................................................................................................... 18
Respiratory infections ............................................................................................... 19
Urinary/Reproductive Infections .............................................................................. 19
Dermatology ................................................................................................................. 20
Mites ......................................................................................................................... 20
Head Tilt Presentation............................................................................................... 21
Guinea Pigs (Cavia porcellus) .................................................................................. 23
Diet ................................................................................................................................ 23
Trauma .......................................................................................................................... 23
Dermatology ................................................................................................................. 24
Scurvy (Vitamin C Deficiency) .................................................................................... 24
Malocclusion ................................................................................................................. 24
Gastrointestinal Disease ................................................................................................ 25
Urogenital System Disease ........................................................................................... 26
Ocular problems ............................................................................................................ 26
Hospitalization .............................................................................................................. 27
Pre and Post Surgical Considerations ........................................................................... 27
Guinea Pig Orchiectomy (with a note on Prairie Dogs) ........................................... 27
Chinchillas (Chinchilla laniger)............................................................................... 31
History and Preliminary Physical Examination ............................................................ 31
Common Presentations: History and Clinical Findings ................................................ 32
Anorexia, weight loss................................................................................................ 32
Dermatologic Conditions .......................................................................................... 32
Ocular lesions............................................................................................................ 33
Diarrhea..................................................................................................................... 33
Constipation .............................................................................................................. 34
Straining to urinate .................................................................................................... 34
Restraint and Handling ............................................................................................. 35
Hands on Physical Examination ............................................................................... 36
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Prairie Dogs (Cyonomys ludovicianus) .................................................................. 39
Respiratory disease ....................................................................................................... 39
Clinical techniques ........................................................................................................ 40
Physical examination ................................................................................................ 40
Venipuncture ............................................................................................................. 40
Anal Sac Triad .......................................................................................................... 41
Rats – Quick Facts ....................................................................................................... 42
Mammary tumors .......................................................................................................... 42
Respiratory Disease ...................................................................................................... 42
Hamsters – Quick facts ............................................................................................... 44
Notes................................................................................................................................ 45
References ...................................................................................................................... 46
Recommended Reading .............................................................................................. 46
Additional references available upon request ....................................................... 47
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Rabbits (Oryctolagus cuniculi)
The domestic rabbit, Oryctolagus cuniculi, maintains the physiology and behavior
of a prey species. The release of epinephrine and its related compounds in response to
stress or pain can cause renal ischemia, with subsequent endotoxemia and death. The
notoriously poor recovery rate from anesthesia in rabbits is often due to pain, and the use
of analgesics (as in discussed in the section on this subject) has greatly increased the
success rate of surgical procedures in rabbit patients. In addition to analgesia, we must
recognize that rabbits are very susceptible to stress in the form of excessive stimulation or
handling, and the scent, sight or sound of potential predators (i.e. dogs, cats, ferrets). The
avoidance of these debilitating factors in the hospital environment can make a great
difference in recovery.
Rabbits that are well acclimated to their captive environment generally have
better recovery rates from illness that their more wild counterparts. Unfortunately, we
cannot choose our patient’s temperament. Observation of the rabbit’s behavior will help
identify those that are “adrenaline rushing” and therefore warrant not only a more careful
approach but also a guarded prognosis, regardless of the underlying disease. Frightened
rabbits have more rapid respiratory rates, and sit motionless in a crouched, ready to jump
position with wide unblinking eyes. Rabbits that are relaxed will usually move around the
exam table or floor, sniffing at the surface and blinking their eyes in a normal manner.
When in the cage, these acclimated rabbits may recline in a semi-recumbent position,
with the rear end extended (this can also happen with severely ill, or rear end paralysis
rabbits, but these are usually obvious to the veterinarian).
It is best to examine frightened rabbits while seated on the floor (you, and the
rabbit). If the rabbit struggles it can be released, or if it escapes it will not have a long
way to fall, therefore avoiding spinal trauma or leg fractures. Covering the eyes of a
rabbit whether with a towel, or by tucking its head into your axilla (polite way of saying
armpit.) will have a calming effect by removing visual stimulation.
Occasionally, you will have an aggressive rabbit that will thump its feet at you
when you approach, or actually attack and attempt to bite. Once again, due to the
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propensity for these rabbits to move/jump quickly and risk skeletal damage, handling
them on the floor in a closed room is the safest method.
Rabbits can be picked up a variety of ways. Dr. Susan Brown has an excellent
synopsis on various methods of restraint in the article “Clinical Techniques in the Rabbit”
in Seminars in Avian and Exotic Pet Medicine - Clinical Techniques - April 1997, Vol. 6,
No.2. In summary, these methods all involve the idea of either scruffing the rabbit, while
supporting the hindquarters to prevent kicking, or hiding the rabbit’s head to decrease
stimulation, while once again supporting the hindquarters. This article also contains a
detailed explanation of the method she advocates for toenail trims, both in the office and
for owners to practice at home.
Physical Examination
Performing a complete physical examination on an awake fractious rabbit can be
a challenge. The most difficult aspect is examination of the oral cavity, since rabbits often
violently object to having their heads elevated, much less their mouths opened.
Generally, with an assistant seated, the rabbit can be held like a child sitting in the lap,
and either an otoscope with a regular large size cone attached, or a special modified
speculum for the otoscope head can be utilized. This author has found that a pediatric
laryngoscope can also be used to visualize molars and perform molar trims on rabbits,
guinea pigs and chinchillas. One big take home point is that although overgrown
incisors can happen independently they are often the result of malocclusion and lack
of wear due to a primary molar malalignment. The molars can overgrow considerably,
causing oral and lingual ulcerations, inability to masticate and even partial occlusion of
the pharynx. Rabbits tolerate isoflurane and sevoflurane very well. If one is comfortable
with these anesthetics, but not experienced with rabbit restraint, it may be wise to mask
the rabbit with inhalant anesthesia and get a quick look, rather than struggling with an
awake rabbit.
Incisor removal
Overgrowth of both the incisors and the molars of rabbits may occur. Generally,
congenital malocclusion is presented in young rabbits, with obvious overgrowth of the
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incisors. Older rabbits are more likely to have gradual overgrowth of molars, with
subsequent inability to masticate the food, and secondary incisor overgrowth from the
molar malalignment and lack of incisor wear. Every rabbit should have both the incisors
and molars checked as part of the routine physical examination.
The young rabbit that presents for abnormal incisor occlusion has historically
been destined to have its teeth trimmed on a very regular basis for its entire life. The
alternative to this is the extraction of all six incisors (two lower, and four upper). This has
been shown to be well tolerated in most rabbits, with the most common side effect in my
experience being mild lip fold dermatitis. The procedure is not difficult, but the length of
the roots of the upper incisors makes it critical that all ligaments, especially those on the
medial aspects, be completely severed prior to attempting extraction. The position of the
teeth within the oral cavity should be visualized as the direction in which to extract the
incisors is determined, so as not to fracture them. If a fracture does occur, and the vestige
of the tooth is not accessible, the remainder of the incisors can be extracted and the rabbit
can be rescheduled to have the fractured tooth extracted when it grows out to an
accessible length - usually about 6 weeks. Postoperative analgesia, and supportive care
with syringe feeding are critical for the first 24-48 hours or until the rabbit is eating on its
own.
Molar malocclusion
Overgrown incisors are often the result of malocclusion and lack of wear due to
molar malalignment. The most common presenting complaint is anorexia. Unfortunately,
many of these animals leave the veterinary hospital with only the incisors trimmed. It is
not until the anorexia persists, and the pet is further debilitated, that a thorough oral
examination reveals the molar malocclusion. The molars can overgrow considerably,
causing oral and lingual ulcerations, inability to masticate and partial occlusion of the
pharynx. This presentation is generally seen in the adult animal. Clinical signs indicative
of potential occlusion problems include anorexia, “slobbers” (wetness of the chin and
dewlap), and grinding of the teeth.
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The oral cavity is extremely small and visualization is difficult. Some animals
will tolerate being held like a child sitting in an assistant’s lap. Others are more docile
when allowed to stand in a normal position on an examination table, while the
veterinarian squats down to the level of the oral cavity. Some animals are too fractious, or
too painful, to allow an oral examination while awake. Rabbits tolerate Isoflurane very
well. If one is comfortable with this anesthetic but not experienced with restraint, it may
be wise to mask the animal with isoflurane rather than struggle with a fractious patient.
Note: It is not necessary to identify all of the involved dentition on initial inspection. If
dental disease is present, and it has been determined that sedation will be needed for
treatment, the oral examination needn’t be prolonged. This only upsets the pet (and the
owner, when present). A thorough examination can be done under sedation or anesthesia
while performing the molar trim.
This author has found that the index finger inserted between the buccal mucosa
and the molars can often palpate sharp edges without visualization. Admittedly, the pet
will not appreciate this procedure, and it should be done quickly (and possibly only by
less intelligent veterinarians, like myself). To date, no bite wounds have occurred from
this procedure, although the need to retract one’s digit rapidly has led to minor
lacerations of the finger from the edges of the molars.
Numerous suggestions for equipment to aid visualization of the molars have been
made, and this list includes:
1) An otoscope with a regular large plastic cone attached.
2) A special modified metal speculum for the otoscope head (Welch AllenR,
FocuscopeR).
3) A pediatric nasal speculum.
4) A rigid endoscope, which undoubtedly provides the brightest light. Drawbacks
include that not all practices have this piece of equipment, and great care must be taken
not to damage the optics.
5) A pediatric laryngoscope, which contains a bright light source at the tip, is
constructed of metal, and has a single blade that allows maneuvering to retract buccal
mucosa while visualizing the molars.
6) Various ophthalmic retractors.
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7) Multiple manufacturers have designed equipment specifically for rabbit and rodent
dental procedures. Universal Instruments, Jorgenson and Sontec are among those
companies
For the actual trimming of the molars, options include:
1) Ronguers (small bone rongeurs)
2) Dental drills
3) DremmelR electric sanders or the equivalent, with extensions.
4) Bone rasps
The dental drill allows more smoothing of the sharp edges than the hand held rongeurs,
but carries the risk of accidentally abrading the adjacent soft tissue and the production of
excessive heat. Also, not all dental drills will allow manipulation into the oral cavity due
to their size or configuration. The V-shaped toe nail file for birds can be used to smooth
rough edges that remain after the majority of the trimming has been accomplished with
rongeurs.
Options for sedation, analgesia and anesthesia include:
1) Butorphanol tartrate (TorbutrolR or Torbugesic) @ 0.05-0.5 mg/kg IV, SC, IM q 4-6
hours). This medication has only a minimal sedative effective, and is most useful
when the patient is complacent, but painful on examination due to oral ulceration. It
can be repeated as dosed above after the completion of the molar trim, to allow more
rapid return to eating.1,3,5,6
2) Buprenorphine @ 0.01 – 0.05 mg/kg SC or IM. Lasts longer than butorphanol
(approximately 8 hours) and provides excellent analgesia.
3) Midazolam @ 1-2 mg/kg I.M. This is useful alone to decrease anxiety and
epinephrine release in rabbits (and guinea pigs) that are hospitalized. Some authors
report that it is clinically more efficacious than diazepam.
4) Diazepam @ 1-5 mg/kg IM or IV
5) Medetomidine @ 0.1 – 0.5 mg/kg IM
6) Ketamine hydrochloride at 15-25 mg/kg IM often combined with one of the above
medications.
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7) Isoflurane or Sevoflurane alone, or after pre-medicating with one of the above
medications. When used alone, there may be insufficient time to work in the mouth
when the facemask delivering the inhalant anesthetic is removed. However, since
rabbits are nasal breathers even under anesthesia, the end of the anesthetic tubing can
often be held over the rabbit’s nares while the mouth is open. This allows continued
delivery of inhalant anesthesia to the patient.
If oral abrasions or ulcers are present, prophylactic antibiotics may be warranted,
bearing in mind the rabbit’s intolerance for narrow spectrum oral antibiotics that are
active against gram-positive bacteria.
Analgesia or anti-inflammatory agents administered post-operatively and
continued at home for several days may aid the pet in a more rapid return to eating.
Butorphanol tartrate or buprenorphine as dosed above are commonly utilized. For more
chronic inflammatory pain, flunixin meglumine (Banamine @ 1.0 mg/kg SC q 8 hours)
for three days out of seven, may be effective. Various non-steroidal anti-inflammatory
drugs have been used in rabbits including meloxicam, carprofen and piroxicam.
If inanition has been a problem (and it is often the presenting complaint) then the
patient should not be released until it has returned to eating. The owner may try the pet at
home to see if the decreased stress stimulates its appetite. If not, syringe feeding and
subcutaneous fluids should be administered to prevent further debilitation.
If tooth root infection is present then a culture should be taken of the affected
tissue, NOT of any caseated purulent material that may be exuded since this is composed
of desquamated epithelial cells, dead bacteria, and leukocytes.
The trend in the United States to feed a diet with less calcium in order to help
prevent calcium oxalate uroliths in rabbits may be misguided. Recent research by Frances
Harcourt -Brown of the U. K. (I.C.E. Conference, Delray Beach, 1999), indicates that
calcium deficiency may add to or cause the bony lysis that predisposes these animals to
dentition problems. This evidence, including the measurement of parathyroid hormone
levels and Vitamin D levels in rabbit populations with various diets and environments,
was quite remarkable and in keeping with the radiographic evidence of decreased bony
density often noted in these affected animals. We may be inadvertently adding to the
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inherent problem of rabbits by further decreasing dietary calcium. Other factors, such as
sufficient roughage for normal dental occlusal wear, access to both sunshine (normal UV
for Vitamin D3 formation) and dietary natural grasses may be involved in this situation.
Further research is needed to determine the etiologies behind rabbit dental disease and
malocclusion.
Analgesia / sedation
As mentioned above, the success of treatment can be decreased in rabbits that are
severely stressed by pain or fear. In a prey species such as the rabbit, signs of discomfort
or pain may include grinding of the teeth, anorexia, hiding, and being slow to respond to
stimuli.
Post surgical analgesia, as stated in the section on surgery, has greatly
increased the speed and percentage of survival. The same medications can be used
on presentation of a rabbit in pain prior to surgical intervention (i.e. a fractured
tibia, lacerations). Several medications have been utilized. An effective and readily
available agent is butorphanol tartrate (TorbutrolR @ 0.05-0.5 mg/kg IV, SC, IM q 4-6
hours). A dose of 0.1 mg/kg subcutaneously is usually given initially immediately postop, and repeated or increased if needed. Buprenorphine (Buprenex®) has a longer
duration of action and is this author’s favorite peri-operative analgesic agent, at 0.03
mg/kg q 6-8 hours. For more chronic or inflammatory conditions such as arthritis and
perineal dermatitis, flunixin meglumine (BanamineR 1.0 mg/kg SC q 8 hours) is often
effective though prolonged usage may cause gastric disturbances. For a more
comprehensive list of non-steroidal anti-inflammatories utilized in the rabbit, see item
number four on the recommended reading list following this article.
Injections
Rabbits tolerate subcutaneous injections extremely well. Many owners find
injectable antibiotics easier to administer at home than oral medications. See the section
on “Venipuncture” for a discussion of accessible veins for I.V. injections. One note of
caution is that although collecting blood from the central auricular artery can work
well when obtaining small quantities, injection of medications INTO this artery,
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especially medications with tendencies for perivascular irritation, can cause
sloughing of the delicate tissue of the pinna. (This author has produced a permanent
“pierced ear” appearance in response to extravasated I.V. ketamine).
Venipuncture
The rabbit’s blood volume is approximately 6 - 7% of the body weight. Therefore
a 1.5gm (approximately 3 lb.) rabbit has a blood volume of 90 - 100 ml. On a healthy
rabbit, 10% of this (about 9 ml) can be collected safely at one time.
Generally, 27 - 25 gauge needles are a good size for blood collection. The
cephalic vein can be visualized readily and utilized as in a dog or cat for small volumes
of blood (such as for a CBC or a blood glucose). The central auricular artery is the
favorite site of collection for many veterinarians dealing with rabbits. The major
drawback to this artery is that hematoma formation is common, so be certain to apply
digital pressure for a sufficient period after venipuncture. The marginal ear veins, in all
but the largest rabbits, often collapse during venipuncture. The lateral saphenous vein, as
in the dog, is a good site for collection though the person restraining must be careful to
hold the rear end firmly, yet without causing spinal trauma. Rabbits seem to tolerate this
position and location surprisingly well. Members of the House Rabbit Society will
demonstrate this method.
As in most species, the jugular vein will give the fastest and most consistent blood
draw. However, on an awake rabbit, the experience of the person performing
venipuncture and person restraining, along with the temperament of the rabbit, gives
variable success with this technique. If the rabbit is under anesthesia the jugular should
certainly be utilized.
Fluid administration
I.V. catheters, and I.O. catheters can be used successfully in debilitated rabbits.
Rabbits that are still responsive and able to chew, however, are difficult candidates both
for placement and maintenance of these devices. The veins generally utilized are the
cephalic, jugular, and lateral saphenous. In this author’s experience, subcutaneous
fluids, with the addition of hyaluronidase (WydaseR) at 100-150 Units/liter of fluids,
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greatly speeds absorption of the fluid from under the skin. This makes it
unnecessary to use I.V. of I.O. fluid therapy in all but the most debilitated (and
therefore, most complacent) rabbits.
Surgical considerations
As stated previously, it is not necessary to fast rabbits prior to anesthesia, since
they do not regurgitate. The exception would be gastrointestinal surgery, when a fast of
6-8 hours may be useful in decreasing the quantity of gastrointestinal contents.
During anesthesia, due to the small size of the thorax (as in prairie dogs) the
cranial aspect of the animal should be elevated, to reduce pressure on the chest and
increase tidal volume.
Intubation of rabbits can be difficult, and laryngospasm is common. If intubation
is necessary due to the nature of the surgery, use of a laryngoscope and a topical
anesthetic applied to the glottis may facilitate intubation. Generally, maintaining the
rabbit with a cone (mask) is easier and may be preferable.
Abdominal adhesions are more common in rabbits than in most other animals.
Removing excess powder from the gloves and being gentle with tissue handling may
prevent adhesions.
Closure, as with most animals prone to chewing at external sutures, is best
accompanied with a subcuticular pattern.
Ovariohysterectomy
Uterine adenocarcinoma is the most common neoplasia of female rabbits.
Because the incidence of uterine cancer is so high, it is usually recommended that all
female pet rabbits be “spayed” before they are two years of age. Endometrial hyperplasia,
uterine polyps, pyometra and endometritis are also known to occur in rabbits.
Signs of disease of the female rabbit’s reproductive tract may include hematuria,
serosanguineous vaginal discharge, decreased fertility, cystic mammary glands and an
enlarged uterus on palpation.
Recommended pre-surgical diagnostics depend on the reason for surgery. A
routine ovariohysterectomy should ideally be preceded by a complete blood count and
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serum chemistries. (Note: the major variation in rabbit serum chemistries is that the
calcium is normally higher than that of other mammals. This is not always stated as
such in the literature, where the normal range is reported to be 5.6 - 12.5mg/dl. In
this author’s experience, values above 10 mg/dl are the norm). If the rabbit is
suspected of having uterine adenocarcinoma, it should also have pre-surgical thoracic
radiographs. Clinically ill patients should be evaluated and treated as indicated for
anemia, dehydration, or systemic infection.
Rabbits may be fasted for 2-4 hours prior to surgery to reduce the pressure of a
full stomach on the rabbit’s thorax. A longer fast may increase the chances for gut stasis
post surgically. It is not necessary to withhold water.
Clip and prep the ventral abdomen from the pubis cranially to the umbilicus.
Rabbits have delicate skin and very thick fur that makes the clipping required for surgery
a challenge. Keeping the skin flat and tight will help avoid skin tears. Gently express the
rabbit’s bladder prior to surgery.
Chlorhexidine or iodine surgical scrub can be used to prepare the surgical site.
Rabbits will often get a post surgical dry skin flakiness that is quite pronounced within a
week or so post-operatively. The use of chlorhexidine, and using gentle technique may
decrease this occurrence.
A ventral midline incision through the skin is begun about half way between the
umbilicus and the cranial rim of the pubis. Be careful not to penetrate the linea that is
often thin and slightly transparent. Carefully incise the linea in a routine manner. The
bladder may be directly underlying the incision. Locate the uterine horns dorsal to the
cranial pole of the bladder. The uterus is bicornuate and there is no uterine body. Each of
the uterine cornua possesses a cervix. The mesometrium is a site of fat storage making
identification of vessels difficult.
The oviduct is much longer than in a dog or cat and coils around in a loop.
Carefully identify the ovaries and the entire oviduct to each ovary, then locate the ovarian
vessels. In rabbits that have not yet cycled, or are not in estrus, these vessels may be very
small, and imbedded in fat. Ligate the ovarian vasculature with absorbable suture. Cut
between your ligation and the ovary and check for bleeding. Manually break down the
mesometrium from the ovary towards the cervices. Locate the uterine vessels embedded
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in the fat several millimeters lateral to the uterus. Some rabbits in estrus may have
pronounced mesometrial vessels that may require clamping and /or ligation.
Next, locate the left ovary and oviduct and repeat the procedure. Ligate the
pedicle, double clamping with hemostats and break down the mesometrium to locate the
uterine vessels on the left side of the cervices. Double ligate these vessels. Identify the
two cervices and the cranial vagina. Each horn of the uterus can be transfixed and ligated
just cranial to the cervices or the cranial vagina can be ligated just caudal to the cervices.
Ligation of each horn cranial to the cervices has advantage of making the inadvertent
entrapment of a ureter less likely. Double ligate and use a transfixing, absorbable suture,
then clamp and cut the uterine stump. Closure of the linea is routine. A final subcuticular
closure is often utilized when the practitioner is comfortable with this technique, since the
absence of any external sutures makes the rabbit less prone to chewing at the incision.
Skin sutures, if utilized can be removed in 7-10 days.
Post-operative Considerations
It is critical to get rabbits eating soon after surgery. Since they often become
anorectic when uncomfortable, analgesics are highly recommended following painful
procedures (see section on analgesia). Anorectic rabbits may need to be syringe fed for
24 - 48 hours to prevent hepatic lipidosis and gut stasis if they refuse food after surgery.
Hospitalized rabbits should be provided with their usual diet and protected from stress
related to the noise, sight, or odor of dogs, cats, snakes, ferrets or other potential
predators.
Castration
Male rabbits that are not castrated usually have an objectionable odor, as well as a
tendency toward aggressive behavior. Castration is well tolerated by male rabbits, with a
few precautions. The skin around the perineum and scrotal area tears very easily, and
extreme care must be taken while clipping for surgery. Generally, the scrotum must have
an incision made over (and slightly laterally) to each testicle. A closed castration will
avoid the danger of herniation from the open inguinal rings. Double ligate, and observe
the spermatic cord once it has been returned to the abdomen to be certain that the
ligatures are secure. Post -operative butorphanol is indicated not only for discomfort and
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rapid return to eating, but also to minimize activity, thereby avoiding hemorrhage.
Closure is routine: subcuticular, tissue glue, or leaving the incision open and manually
opposing the tissue. Generally, especially in younger rabbits with less developed testes,
the tissue will adhere to itself and heal much like in a cat. This author feels safer
however, with a subcuticular closure that also opposes the fascia over the inguinal
canal. Be certain that the rabbit’s testicles are readily palpable prior to surgery.
Young rabbits (under 8-20 weeks, depending on the individual and the breed) may
have either undescended testicles, or testes that retract readily into the inguinal
canal.
Gastrotomy
Subacute to chronic gut stasis is a common syndrome in pet rabbits, often
associated with the presence of trichobezoars or “hair balls.” Rabbits fed a low fiber, high
carbohydrate diet are particularly prone to this syndrome. Whether trichobezoars act as a
primary etiology of gastrointestinal stasis is still subject to debate.
General clinical signs of hairballs include inappetance, a decrease in size and
number of stools, and lethargy. However, it should be noted that these symptoms are also
suggestive of numerous other diseases in rabbits. Dental problems and cardiomyopathy
should be ruled out before trichobezoar is considered to be the primary problem.
It should also be noted that a certain amount of hair in the stomach of rabbits may be
normal and will not necessarily cause illness. Hepatic lipidosis is a common sequela to
anorexia in rabbits and may complicate diagnosis and post-surgical recovery.
When other diseases are ruled out, medical treatment with analgesia, parenteral
fluids, oral cat laxatives, simethicone and metoclopramide at 0.2 to 1.0 mg/kg IM, SC, or
PO every 8 to 12 hours, and syringe feeding with a high fiber/low carbohydrate diet
should be tried for several days before surgery is considered. The use of both simethicone
and metoclopromide are of questionable use for gastric stasis, and further research is
needed to document whether these agents are efficacious in this condition. If medical
treatment is successful, long-term management includes: increased hydration, increased
brushing to remove loose hair, increased activity and increased fiber in the diet.
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Gastrotomy for removal of trichobezoars in rabbits should be considered only after
medical treatment has been unsuccessful.
Lack of successful medical treatment has, in this author’s experience, often been
associated with the inter-operative finding of fibers (carpet fibers, cloth) along with the
trichobezoars. Owners should be given a guarded prognosis until the rabbit begins to eat
well again post-surgically. It may take days to weeks of supportive care before the
surgical patient returns to normal.
Rabbits with trichobezoar and associated foreign fibrous material are not eating,
therefore fasting will be of minimal concern. It is not necessary to withhold water.
Prophylactic antibiotics such as enrofloxacin at 5 to 10 mg/kg IM every 12 hours may be
started and any pre-existing dehydration should be corrected prior to gastrotomy.
Tracheal intubation is preferable to a facemask for gastric surgery.
The initial midline abdominal incision is made between the umbilicus and the
xyphoid process. The initial incision is extended to allow access to the stomach and
visualization of the liver and intestines. When incising through the linea, care is taken not
to damage the organs immediately below. The stomach is located and gently exteriorized.
Laparotomy pads are placed along the incision line and moistened with warm saline. Stay
sutures are placed in the greater curvature of the stomach. An incision is made through
the stomach body wall between the greater and the lesser curvatures, avoiding the larger
vessels. The trichobezoar is grasped and gently extracted by careful manipulation. These
hairballs are firm and well-packed together, often remaining in one piece during removal.
The stomach lumen and pylorus are examined for abnormalities. The gastrotomy incision
is closed using a two-layer inverting suture pattern with 3-0 or 4-0 synthetic absorbable
suture material. The sutures should incorporate but not penetrate the gastric mucosa.
Copious amounts of warm saline flush are used to lavage the serosal surface of the
stomach without contaminating the abdomen. The linea is closed with 3-0 synthetic
absorbable sutures in an interrupted pattern. Continuous subcutaneous absorbable sutures
are placed. These are followed with continuous subcuticular sutures. Rabbits commonly
chew out skin sutures. Skin staples may be effective and tolerated by rabbits if the
surgeon prefers these to subcuticular sutures. Other practitioners have found that rabbit
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incisors are perfectly designed to be used as staple removers. Some surgeons have also
used tissue glue successfully.
Post-operative treatment and considerations are as noted above under
ovariohysterectomy. The extracted trichobezoar should be examined to determine if
foreign material such as fibers from carpeting or blankets is present. The owner needs to
be made aware of the presence of these materials, and remove them from the rabbit’s
environment.
Once recovered, the client should be counseled on proper rabbit diet. High fiber is
essential. Pellets should be limited or excluded altogether in rabbits that are not growing,
gestating or lactating. Fresh high quality grass hay should be fed ad lib along with 1 to 2
cups of fresh clean leafy greens and other low carbohydrate vegetables. Proper diet will,
in many cases, prevent the formation of the potentially pathologic trichobezoar.
Sufficient exercise, regular brushing, and the use of a prophylactic “hair ball” medication
will also aid in preventing recurrence.
(Portions reproduced with permission of Zoological Education Network, Inc. copyright
1997)
Common Disease Syndromes
Abscesses
Rabbits tend to develop large abscesses with purulent material the consistency of
cream cheese (nice image, huh?) Though it is tempting to culture a big wad of this lovely
material, it is generally old WBCs and dead bacteria. The wall, or capsule, of the
abscess should be used for culture. Anaerobes are very common in rabbit abscesses
and be forewarned (and forewarn the owners) that negative aerobic cultures are
common despite the obvious presence of bacteria. Therefore, a gram stain taken at
the same time as the culture will allow you to start on an antibiotic chosen with the
class of bacteria present in mind, and will allow you to continue that treatment
should the culture prove non-productive.
Besides systemic antibiotics (both enrofloxacin at 10 mg/kg S - BID and Dual
penicillin -procaine and benzathine- at 50,000 u/kg subcutaneously or intramuscularly are
commonly utilized. Empirical evidence indicates that more frequent administration of
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long-acting parenteral penicillins (every 48 hrs is commonly recommended) may be an
effective treatment in many cases of abscessation. The implantation of acrylic antibiotic
impregnated beads or umbilical tape of a fibrous absorbable hemostatic agent (such as
Surgicell® or Gelfoam® soaked in an antibiotic as both a drain and a source of antibiotic
release, show promise in treatment of these abscesses. Extensive surgical excision is
ideal, however, the location, extensive nature, and heavy vasculature of many of these
abscesses make this impossible. The use of packing material soaked in 50% dextrose to
inhibit bacterial growth has been used with good success in some cases (S. Kelleher, per
com 3/2003, details in Proceedings of I.C.E. 2001.)
Epiphora
Dacryocystitis presents with unilateral epiphora and may be accompanied by
facial irritation or dermatitis. Bilateral epiphora can also be caused by dacryocystitis, but
in the presence of bilateral epiphora, especially if the discharge is not clear, an infectious
primary cause, such as Pasteurellosis, should be investigated..
When dacryocystitis is suspected, the naso-lacrimal duct should be cannulated
and flushed. This can be accomplished either with topical ocular anesthetic, or with
general anesthesia. The puncta is quite large and prominent, but can be difficult to
visualize if the peri-orbital tissue is inflamed and swollen. Although the time of
cannulation is the opportune moment to obtain cultures, on occasion we have to treat the
eye with a combination antibiotic/corticosteroid drop for 3-5 days in order to decrease the
swelling and visualize the puncta.
When cannulating the duct, any cannula that will fit in the opening and with
which the practitioner is comfortable, will work - from regular naso-lacrimal cannulas to
tom cat catheters. Often the first few attempts at flushing will result in a back flow of
whitish purulent discharge into the peri-orbital area. Subsequent flushing will hopefully
clear the occluded nasolacrimal duct. Excessive pressure should NOT be applied. The
nasolacrimal duct can rupture, and the effect will be an immediately noticeable
periorbital swelling as the saline infuses into the surrounding tissue. This swelling will be
absorbed in a matter of hours, but the integrity of the nasolacrimal duct will then be
questionable. If you find it difficult to determine if the duct is patent, Fluorescein stain
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can be used in the eye ,followed by a Woods lamp to check for the appearance of the dye
in the nare. The addition of hyaluronidase to the flush will in many cases facilitate the
breakdown of caseated debris.
Respiratory infections
Three major bacteria are commonly isolated from respiratory infections of rabbits;
Pasteurella multocida, Staphylococcus aureus and Bordetella bronchiseptica. Of these,
the first two are also the most common in cutaneous abscesses. A mini-tip culturette
introduced into the medial aspect of the sinus (quickly in and out as far as it will go) may
yield a positive culture. Most rabbits don’t appreciate this procedure, and will jump. A
small amount of blood may appear on the culturette or on the rabbit’s nare. Allow the
rabbit to sit quietly for a few moments and when its blood pressure drops, the bleeding
will stop. Again, a preliminary gram stain may allow early initiation of appropriate
therapy, and prevent the over interpretation of positive culture results from contaminants.
Also, with the fastidiousness of Pasteurella, a negative culture may simply indicate a
problem in sample processing, not the absence of bacteria.
Pasteurella titers are also available to evaluate exposure to this organism. Since a
high percentage of rabbits may be latently infected, the titer should be interpreted
accordingly. A very high titer, a rising paired titer, or a titer that decreases after treatment
and an improvement of clinical signs gives a presumptive diagnosis of Pasteurellosis.
Pasteurella can be difficult to isolate from both abscesses and nasal cultures, but a
positive culture is confirmatory. A gram stain will also give you a reasonable idea of the
presence of Pasteurella.
Urinary/Reproductive Infections
Rabbits often present for either; discolored urine, odiferous urine, or vaginal
discharge. The porphyrin pigment that occurs in rabbit urine as an orange tinge is normal.
However, many practitioners see this orange pigment produced with greater frequency in
rabbits that are stressed, either due to illness or other factors.
Uterine infection and uterine adenocarcinoma are common, as are cystitis and
cystic calculi. A urinalysis is often helpful, preferably obtained via cystocentesis since a
clean sample can aid in differentiating these syndromes.
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Dermatology
Mites
Psoroptes Cuniculi is the ear mite of rabbits, and can cause considerable damage
and discomfort, not only to the external pinna, but also to other parts of the body. With
the advent of Ivermectin, the treatment of choice is the injection of Ivermectin at 300 400 mcg/kg subcutaneously q 2-3 weeks for three treatments. When the ears are
severely infested, and secondary infection is present, aggressive cleaning and
debridement should NOT take place until after at least the second treatment. The
ears of these rabbits are extremely painful and ulcerated under the crusting, therefore
cleaning will likely cause self-mutilation, pain and bleeding. If necessary, an
antibiotic/cortisone cream may be gently and sparingly applied. After the mites have been
eradicated, a more thorough cleansing can be performed without discomfort.
Cheyletiella parasitovorax is the rabbit fur mite. As in dogs and cats, it can
exhibit a varying response, from just slight dryness of the skin, to more severe
excoriation and pruritus. Diagnosis can be made by the naked eye (if you are under 45) or
with a scotch tape prep under the microscope. Since the mite eggs of this parasite are
located on the hair, treatment generally consists of both Ivermectin - at the same dose and
interval as for Psoroptes - but with the addition of cleaning of the environment and
bathing of the rabbit in an insecticide shampoo. Carbaryl is effective, and well tolerated
by rabbits. This parasite is potentially contagious to other pets and to humans.
Dermatophytes are not common in pet rabbits, but both Trichophyton
mentagrophytes and Microsporum sp. have been identified. Traditional treatments
following protocols used in the feline have been advocated; either localized topical
treatment with antifungals after clipping the hair, and/or Griseofulvin parenterally.
Lufenuron is now being used in rabbits and rodents for dematophytosis with anecdotal
reports of good success.
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Treponema cuniculi is the spirochete that causes rabbit syphilis. It has a
characteristic appearance, with the genitalia and the face (from autoinfection) involved.
Many times pet rabbits are presented when the facial lesions develop, since the perineum
is not as closely observed by owners. The disease has a severe crusting and proliferative
component. A biopsy, requesting special stains for Treponema, is confirmatory.
Treatment with injectable long acting penicillin (penicillin G - procaine or benzathine) at
50,000 units/kg subcutaneously once or twice weekly for 2-3 weeks is usually curative.
Other effective drugs include the tetracyclines.
Head Tilt Presentation
The most common presentation of torticollis in a rabbit is an acute onset in the
absence of other external signs. Obvious trauma or acute otitis externa may cause a head
tilt, but these would be readily visible on the physical examination. A common cause of a
sudden onset of a head tilt with other signs of vestibular disease may be an inner ear
infection. These rabbits may have nystagmus, and may roll uncontrollably- injuring
themselves in the subsequent panic. Valium or meclizine are often helpful initially to
decrease the stress and trauma of this acute presentation. To attempt to confirm the
presence of Pasteurella, titers are available (see the section on Pasteurella) since the inner
ear is not accessible for culture. Many practitioners have had excellent results with the
use of enrofloxacin , with the head tilt resolving partially or completely. However, after
the cessation of antibiotic therapy, the head tilt may recur. Many rabbits require long term
antibiotic therapy to control this disease. Other practitioners report that in many rabbits
the head tilt resolves to a great degree with time, without any antimicrobial therapy.
In this author’s opinion, a high percentage of these rabbits, especially the younger ones,
have no sign radiographically or on examination of the tympanum of middle ear
infections. Since the presentation is so similar to vestibular disease of cats and geriatric
vestibular syndrome in dogs, a non-infectious or at least primarily inflammatory
condition of unknown origin may be responsible in these cases. Further research is
needed to determine the cause of this extremely common syndrome, including the
submission by practitioners of tympanic bulla and vestibular nerves and brain of these
rabbits for histopathology at necropsy.
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There is controversy as to whether the organism Encephalitozoon cuniculi can
cause head tilt in rabbits. This microsporidian organism invades the CNS, and can cause
granuloma formation. Titers are available to check for the presence of antibodies to E.
cuniculi. However, many rabbits have positive titers, and no clinical signs. There is no
treatment currently for E. cuniculi.
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Guinea Pigs (Cavia porcellus)
Guinea pigs have become extremely popular as pets. In the past they were
considered a child’s pet. However, it is now common to see them as pets beloved by all
family members. Socialized, healthy guinea pigs will be active and curious about their
environment. They will vocally greet their human companions and produce the same
excited vocalizations in response to the sounds of food being opened. Guinea pigs are
social animals and tend to do better in bonded pairs, however, aggression can occur
between guinea pigs. This is often seen between two adult pigs of either sex and is most
likely with unaltered males.
As a crepuscular species, cavies are most active in the morning and the evening.
Most of the day is spent quietly resting with short periods of activity and food intake.
Guinea pigs are coprophagic throughout the day rather than just in the a.m. as are rabbits.
Diet
Guinea pigs are strictly herbivorous and juveniles will imprint on food items early
in life. It is important to expose them to a variety of nutritional greens and hays in order
to avoid the development of “food phobias”. Free-choice grass hay is a fundamental part
of the guinea pig’s diet as it provides the essential fiber needed in maintaining intestinal
and dental health. Obesity is not uncommon and can be the result of feeding excessive
high calorie foods, a high percentage of pellets or the feeding of seed mix diets. As in
many species, numerous other medical conditions such as hepatic lipidosis,
pododermatitis, and exercise intolerance can all arise from obesity. Vitamin C deficiency
is still a prevalent problem in guinea pigs and will be discussed later in this article. It
should be noted that even pigs fed a guinea pig pellet enriched with Vitamin C will
become deficient if the seed is not fresh and the potency of the Vitamin C is lost prior to
feeding.
Trauma
Trauma is a common cause of injury to the spinal cord or extremities. Guinea
pigs, much like prairie dogs, are not climbers, and falling often causes injury. They are
not cautious or observant of the edge of a table and may walk off and injury themselves.
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If amputation of a limb is necessary, guinea pigs generally acclimate well to three-legged
ambulation.
Dermatology
Barbering can occur when a guinea pig is bored and a dominant pig may barber
other resident guinea pigs. Besides alopecia, this can lead to trichobezoar formation.
Guinea pigs will also barber hair at painful areas of their body
Guinea pigs can get mites, lice and fleas. The sarcoptiform mite, Trixacarus
caviae, seems to produce the most severe generalized effects, due to the high level of
pruritus and pain. Excessive vocalization and even seizures can be seen with mite
infestation. Treatment with Ivermectin at the usual recommended dose
(0.3-0.5 mg/kg) SQ is generally effective when the environment is properly cleaned.
Young guinea pigs, often multiple individuals in a pet store setting, can develop
dematophytosis. Trichophyton sp. is the most commonly isolated organism seen by this
author, but Microsporum sp. with its associated zoonotic concern is also reported. In herd
situations, Program® (lufenuron) administration, repeated in two weeks, along with
cleaning the environment, is generally effective.
Scurvy (Vitamin C Deficiency)
Although the absolute Vitamin C requirement of guinea pigs is widely known,
clinical and subclinical scurvy is still very common. This can be attributed in many cases
to the lability of Vitamin C and the false sense of security owners derive from feeding a
Vitamin C enriched guinea pig pellet that has lost potency. Since collagen is the main
structure affected by Vitamin C deficiency, overt signs of disease will include
hemorrhage and loosening of the teeth. Subclinical signs may mimic those of any other
illness, or exacerbate existing disease. Therefore, treatment with injectable Vitamin C @
50 mg/kg with continued oral supplementation at home at the same dose, is the
recommended treatment. Response to therapy is often the method by which this condition
is tentatively confirmed.
Malocclusion
During the oral examination a green sludge of food is usually present in the oral
cavity. This makes visualization of the dentition difficult and presents danger of
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aspiration when anesthesia is used. This material should be carefully swabbed from the
pharynx once a light plane of anesthesia has been achieved.
Signs of dental disease include: anorexia, ptyalism, and grinding of the teeth.
Prior to this degree of affectation, the owner may notice that the pig is preferentially
eating only certain foods, or chewing on one side of its mouth (tilting its head).
Correction of dental disease follows the guidelines that were introduced in the section
under rabbits. Factors specific to guinea pigs include:
1)
Scurvy is a common underlying reason for malocclusion. The amount
of tooth overgrowth showing above the gum lines may be minimal, but
the angulation of the teeth due to the effects of Vitamin C deficiency
may be severe. This author has recently seen three pigs with scurvy
that had their tongues trapped beneath the lower molars as these molars
overgrew medially. The tongue of these pigs could still protrude from
the mouth, but movement was hindered and painful due to the
overlying molars.
2)
Guinea pigs also have a smaller oral cavity, with more redundant
buccal mucosa than do rabbits, making access to the molars without
causing trauma to the oral cavity, more difficult.
3)
The green sludge in the oral cavity provides a visual barrier and a
concern with aspiration and hypoxia.
Gastrointestinal Disease
A common client misconception is that lack of stool production indicates
constipation. Generally, it actually represents a decrease or absence of food intake.
Enemas should not be given to guinea pigs unless radiographic evidence of obstipation is
documented (which will be a rare occurrence).
Dysbiosis can occur in guinea pigs for the same reasons as it does in rabbits.
Changes in diet or decreased food consumption, and inappropriate antibiotic
administration are the primary offenders. Treatment follows the protocols outlined for
rabbits.
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Urogenital System Disease
As with other herbivorous species, guinea pigs have an alkaline urine. Crystal
formation and subsequent uroliths are common. Bacterial cystitis is also encountered,
either as a precipitating cause of uroliths or as a consequence of disease. With intact
female guinea pigs, cystic ovarian disease, endometritis, endometrosis, and uterine
neoplasia may all cause clinical signs such as stranguria and hematuria and must be
differentiated from primary cystitis. Cystocentesis and abdominal ultrasound are usually
diagnostic.
Cystic ovarian disease is very common in mature intact female guinea pigs.
Bilateral symmetrical dorsal alopecia is a common finding. The cysts often reach a size
that causes obvious abdominal enlargement, and are readily visualized via radiography or
ultrasound. Ovariohysterectomy is indicated.
Uterine or ovarian neoplasia too often presents as an acute, terminal condition.
These tumors have a tendency to hemorrhage and the guinea pigs will often bleed out
internally prior to obtaining a diagnosis.
Male guinea pigs often accumulate fecal material in the perineal folds, and
infection/abscessation can occur. This area should be routinely checked and cleaned as
needed. Fur rings can also occur on the penis of male guinea pigs as they do in
chinchillas, and regular examination by the owner may prevent this from becoming an
emergency.
Ocular problems
An under diagnosed problem in guinea pigs appears to be ossification of the
ciliary body, known as osseous choristoma. The origin and prevalence of this condition is
unknown, and is currently being surveyed by Dr. M. Stengard DACVO at Florida
Veterinary Specialists. This ossification may cause cataract formation or glaucoma. No
prevention or treatment has yet been documented. Practitioners who see guinea pigs with
either glaucoma or cataracts are encouraged to have these patients examined by an
ophthalmologist and screened for this condition.
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Hospitalization
It is important to reduce the stress of guinea pigs being hospitalized. Supplying
them with their customary food dishes and water bottle will help insure continued intake.
The owner should be told to bring the guinea pig’s normal food, both for your assessment
of quality and to encourage continued eating. Avoidance of exposure to the vocalizations
of dogs and cats, especially for pigs not socialized to these species, will also decrease
stress. When hospitalized, pigs will feel more secure if provided with a hide box, shelter
or towel to burrow into and under or to retreat into if startled. These items simulate the
burrows that are often used in the wild for shelter and safety. Guinea pigs are not heat
tolerant. Monitoring of cage and body temperature is necessary to prevent overheating,
both at home and in the hospital.
Pre and Post Surgical Considerations
Guinea pigs do not vomit and it is not necessary to fast them prior to surgery.
They should be encouraged to eat and drink right up to the time of surgery and hopefully
soon after recovering from anesthesia (except after gastrointestinal surgery). The greenish
sludge in the oral cavity is usually present even after several hours of fasting and should
be cleaned to avoid aspiration. As with rabbits, it is critical to provide preoperative and
postoperative analgesics to guinea pigs. Preoperative stress and fear can seriously
compromise the guinea pig patient, as can post-operative pain and stress. Regardless of
the type of surgery, parenteral fluids and syringe feeding are often needed to maintain
G.I. motility and gastrointestinal flora balance.
Guinea Pig Orchiectomy (with a note on Prairie Dogs)
Castration may be performed on guinea pigs to prevent reproduction and any
related objectionable behavior. Orchiectomy may also be needed on occasion for the
treatment of infection, neoplasia, or trauma involving the testes or scrotum.
Prior to surgery the guinea pig should receive a thorough physical examination.
Several conditions of guinea pigs may not be overtly obvious, and therefore not noted by
the owner. These conditions should be diagnosed and treated prior to an elective
orchiectomy. These syndromes include malocclusion, early respiratory disease, Vitamin
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C deficiency, scrotal dermatitis, and pododermatitis or “bumblefoot”. A complete blood
count and serum chemistry tests are useful pre-operative indicators of general health.
Make sure that the testicles are palpable prior to surgery. In the absence of
palpable testes, verify that the patient is a male by locating the penis.
Inhalation anesthesia with isoflurane or sevoflurane is routinely used. Chamber
induction is followed by maintenance with a small face mask. A pre-anesthetic dose of
ketamine at 20 to 30 mg/kg IM may reduce the guinea pig’s resistance to the inhalant
anesthetic and ease induction. Other suggestions for pre-anesthetics may be found in
current texts. Since guinea pigs do not vomit, prolonged fasting is neither necessary nor
desirable. However, withholding food and water for two to four hours prior to surgery
will decrease the pressure of gastric contents on the thoracic cavity and make gastric
reflux less likely. Intubation of guinea pigs, like chinchillas, is difficult and seldom
attempted unless gastric surgery is being performed. Anesthesia is generally maintained
via face mask. Elevation of the upper body will also help prevent gastric reflux and aid in
respiration.
The patient is placed in dorsal recumbency, and the legs are secured. Again,
elevation of the cranial portion of the guinea pig’s body decreases the pressure of the
abdominal organs on the thoracic cavity.
The testicles tend to retract into the abdomen when palpated, especially if the
animal is still under a light plane of anesthesia. Palpation prior to the final scrub is
recommended to develop a “feel” for the location of the testes during surgery.
Starting midway between the umbilicus and the pubis and continuing caudal to
the scrotal area, clip and surgically prepare the patient in a routine manner. An incision is
made over the caudal portion of the testicle. This is the area where the testicle is
generally the most accessible to palpation. It may be necessary for an assistant to extrude
the testicle by externally placing caudal pressure on the cranial aspect of the testicle,
forcing it into the scrotal sac. In guinea pigs that are young and/or obese, locating the
testicles may be more difficult.
The testes are smaller than they appear externally due to the surrounding fat. After
the incision is made through the skin and the underlying fascia, considerable lobulated fat
may exteriorize while the area is being explored. Once the testicle is isolated, the
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ligament of the testes can be gently torn from the tunic and the spermatic cord and vas
deferens may be ligated with absorbable suture in a routine fashion. If there is any doubt
as to the identity of the structure a partial open castration should be performed. A “nick”
can be made in the tunic, allowing the visualization of the classic testicular tissue. A
salient point should be made as the practical reality of orchiectomy on many of these
exotic species with open inguinal rings. Although ideally the castration should be closed,
leaving the tunic intact to prevent herniation, it is extremely common even for
experienced surgeons to nick the tunic as they are incising over the scrotum. The
castration can still be “closed” because the tunic is still accessible, surrounding the
spermatic cord and vas deferens. Ligation of the tunic at this slightly more proximal
location will still serve to provide a barrier to herniation. Seldom is an extensive incision
and closure of the inguinal ring necessary. NOTE: A major exception to this is in the
black-tailed prairie dog. At this author’s practice, although the number of
castrations done on this species is lower than other rodents and related herbivores,
the incidence of inguinal herniation has been significant. Of the last nine prairie
dogs neutered – THREE were known to herniate post-operatively. Fortunately (or
not) the prairie dogs showed no signs of discomfort, and the herniation was not
detected until either months or years later. In a comparable time span, over 200
rabbits were castrated and over 2 dozen guinea pigs, and no herniations were
reported in either of these species. Many surgeons have elected to perform
castrations on prairie dogs from an abdominal approach. This not only prevents
inguinal herniation, but also avoids the difficulty encountered when attempting to
secure the testicles externally during a “routine” castration. Under general
anesthesia, the testicles of prairie dogs tend to return to the abdomen. Another note
on prairie dogs is that, despite claims to the contrary, at the date of this writing,
most babies are “vacuumed” out of their burrows in Texas and are not actually
captive born. This poses both a health risk to the human population and a
population threat to the species. This animal is slated for the endangered species list
as soon as federal funds allow. Double clamping of the spermatic cord proximal to the
testes and epididymis is advisable. A double ligature should also be utilized, due to the
decreased contact of the ligatures with the vessels when a closed castration with the
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intervening tunic tissue is performed. If a full open castration is performed, it will require
more surgical care to prevent post-operative herniation. The inguinal fat can be returned
to the inguinal ring to act as a barrier between the abdomen and the external inguinal
canal. The spermatic cord is severed between the hemostats. The remaining tunic is
carefully replaced into the abdominal cavity, and checked for the presence of bleeding.
Several simple interrupted absorbable sutures or a short continuous suture is then utilized
to oppose the overlying fascia. The procedure is then repeated on the opposite side. A
short subcuticular pattern can then be used to close the incision. The use of a well-placed
subcuticular pattern eliminates the presence of foreign material, such as skin sutures,
staples, or tissue glue and is generally well tolerated by guinea pigs as well as other
rodents. The procedure is then repeated on the opposite side. The completed castration
shows little evidence of the incisions, since the scrotal skin is very elastic, and the small,
subcuticular sutures tend to be hidden in the scrotal tissue. As in many rodents and
lagomorphs, a rapid return to eating is critical to recovery. To reduce pain and anxiety
post surgically, the administration of butorphanol at 0.05 to 0.3 mg/kg SC or IM every
four to six hours has proven effective. Some authors advocate the use of this dosage of
butorphanol pre-operatively to alleviate any lapse in analgesia during recovery. Ideally,
hay should be consumed post-operatively to encourage gastrointestinal activity.
However, the consumption of pellets or a less optimal diet, but one to which the pig is
acclimated and will readily consume, is most important during the initial post-operative
period.
Guinea pigs that are well adapted to their environment and are socialized tend to
have a much better prognosis regardless of the disease. The lack of stress and subsequent
physiologic response that stress induces seems to give these more human-oriented guinea
pigs a greater advantage in tolerating surgery, hospitalization and recovery.
(Portions reprinted with the gracious permission of Dr. Teresa Bradley)
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Chinchillas (Chinchilla laniger)
Originally a native South American species and now either severely endangered
or extinct in the wild, chinchillas inhabit the cool, dry climate of the Andes Mountains.
Therefore, they do NOT tolerate high heat and humidity. They are most active at dawn
and dusk (crepuscular) and at night (nocturnal), but seem able to adapt to more activity
during the day when in captivity. They tend to urinate in the same area but defecation is
not done in any particular location. They do consume their cecotropes, and have a
diminished version of the rabbit cecum, with the same need for dietary fiber to prevent
gastrointestinal problems and malocclusion. Problems with nutrition and husbandry are
extremely common and are often the primary causes of illness in chinchillas.
Chinchillas, like rabbits and guinea pigs, have open rooted teeth with the inherent
potential for various disorders of occlusion. They also have delicate bones, and frequently
acquire fractures of the tibia if they get a toe or a foot caught and attempt to escape.
These distal and often comminuted tibial fractures can be difficult to repair due to the
thin cortices of the bones and the small amount of surrounding soft tissue that contains
and protects the vasculature.3
History and Preliminary Physical Examination
The physical examination (PE) on these “flighty” animals should commence prior
to handling. Hopefully, the owner has brought the animal in a wire cage or other
container that allows visualization without restraint. If not, a pet chinchilla may be placed
on the floor of the closed exam room and observed while you are discussing procedures
and collecting the history from the owner. A healthy chinchilla will be mobile and
curious about its surroundings. The eyes should be wide and bright, and the nose
“twitching”, much like a rabbit's. Normal breathing when excited is rapid, but should not
be labored, open mouthed, nor abdominal. The tail should be held erect, and the fur
(assuming the animal is not presenting for a dermatologic problem) should be thick and
smooth. A rough hair coat indicates husbandry or medical problems (i.e. lack of a proper
dust bath, disease, or both).
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Common Presentations: History and Clinical Findings
Anorexia, weight loss
Clients may present their chinchilla for decreased appetite and weight loss. Less
observant owners may present the chinchilla for lethargy or depression only, and often
this is at a later stage in the progression of the disease. The owner should be questioned
as to whether the chinchilla shows no interest in food, or if it seems initially enthusiastic,
then has difficulty or is reluctant to actually eat. A young chinchilla that is hesitant to eat,
loosing weight, with scant stools, may have a primary incisor malocclusion that has
allowed overgrowth of the incisors to where eating is uncomfortable or impossible. The
history may include observation of moisture around the lower lip, chin and chest. This
may be perceived as the animal being a “messy drinker”, or having some weakness or
problems with swallowing. Other causes of anorexia in chinchillas include: improper
diet, molar malocclusion, excessive heat (chinchillas should not be housed outdoors in
warm climates), respiratory infection/pneumonia (from either poor ventilation, or
infectious conditions), foreign body ingestion, lack of sufficient exercise resulting in
subsequent gastrointestinal stasis, systemic infection, or trauma. In many cases a
thorough history may point in a specific direction, but the owner’s lack of awareness of
any individual clinical sign or occurrence does not rule out that possibility. Chinchillas
are usually kept caged and unless the owner interacts regularly and handles the animal
they may be unaware of wounds, lameness, hypersalivation, fecal impaction, urine scald,
etc.
Dermatologic Conditions
If a chinchilla presents with a “skin problem” the history may be helpful in
diagnosis. Husbandry problems, such as too high an environmental temperature or
insufficient access to a dust bath may contribute to a “scruffy’ appearing hair coat.
Chinchillas kept with other chinchillas may have compatibility problems and barbering of
a cage mate is a common occurrence. Self-barbering can also occur, whether as a
response to boredom, malnutrition, or both. Access to the outdoors, or to potentially
contaminated hay or other bedding material, may make dermatophytosis (usually
Trichophyton mentagrophytes) more likely. Dermatophytosis usually presents on the less-
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furred areas, such as the face, ears and feet. The appearance is much like that in other
species: scaly, generally circular areas of alopecia. Also, as in other species this
appearance itself is not diagnostic, and a fungal culture should be performed. The
presence of fleas or flea dirt is an obvious problem from the history and/or physical
examination.
Ocular lesions
The owner may be able to recount an encounter with a cat, a “fright flight” into a
woven basket or a plant, or some other traumatic event causing corneal or conjunctival
irritation or ulceration. The eyes of a chinchilla protrude much like that of a rabbit.
Luckily, they seem more readily responsive to treatment. On occasion, overuse of the
dust bath, or lack of hygiene in the dust bath will be the inciting cause. Both
conjunctivitis and corneal ulceration are common, and blepharospasm may occur with
either or both conditions. Corneal ulceration is readily detected with fluoroscein stain. As
with other animals, if the conjunctivitis or corneal ulceration does not rapidly resolve
with routine topical treatment, further ophthalmic examinations should be performed.
Diarrhea
A common presenting complaint in chinchillas is diarrhea. Once again husbandry,
specifically incorrect diet, is often the cause. Lack of sufficient fiber is very common in
chinchillas when the owners elect to feed primarily pellets and treats.
Infectious causes of diarrhea do occur, but these are mostly opportunistic
pathogens that affect young chinchillas or adult animals with concurrent debilitating
conditions (such as malocclusion which can lead to inanition, gut stasis, and subsequent
bacterial overgrowth).
The duration of the diarrhea should be determined from the history. Any
associated decrease in appetite or activity should be noted. Observation of the
chinchilla’s behavior in the exam room and the subsequent hands-on physical
examination will aid in determining the general health of the animal. If the clinical
findings show an alert, well-fleshed and hydrated chinchilla, and the history is consistent
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with a good appetite and normal activity, but inappropriate diet, a simple dietary change
may be sufficient.
If the chinchilla is clinically ill, it will need a more complete diagnostic work-up.
This may include a fecal gram stain, (which can identify Clostridial sp. that will not be
detected if the stool is cultured aerobically), CBC and serum chemistries, and radiographs
to demonstrate fecal impaction, gut stasis, or other abnormality. Supportive care with
parenteral fluids for dehydration and syringe feeding for inanition may need to be
initiated immediately. The state of hydration can be determined during the actual physical
examination (see later section). Clinically recognizable dehydration warrants immediate
attention and a guarded prognosis.
Parasitic causes of diarrhea are not common in chinchillas. Be cautious with the
diagnosis of giardiasis as a primary pathogen, and of treatment with metronidazole
(Flagyl). Low numbers of giardia are commonly found in healthy chinchillas. A high
number of Giardia in the presence of diarrhea would warrant treatment. There have been
reports of potential hepatic toxicity with metronidazole use in chinchillas. Albendazole
has been used safely and effectively in cases where the giardia overgrowth seems
involved with the diarrhea.
Constipation
Interestingly, the same husbandry problems that lead to diarrhea can cause
constipation and straining in chinchillas. Insufficient dietary fiber may cause
constipation. Lack of exercise and obesity may also cause straining to defecate, and
small, dry, scant pellets, sometimes with fresh blood on the outside, and containing
copious amounts of fur. Chinchillas that have restricted exercise are often the ones that
occupy their time by chewing fur – either their own, or a cage mate’s.
Straining to urinate
Unlike rabbits and guinea pigs, primary cystitis does not seem to be prevalent in
chinchillas. The report by an owner that a male chinchilla is straining to urinate, licking
himself excessively in the genital or anal area, or reluctance to move, should precipitate a
complete examination of the prepuce and penis. In some chinchillas, this may be best
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performed under isoflurane mask anesthesia. Often male chinchillas will acquire hair that
wraps around the extruded penis (“fur ring”) causing dysuria, paraphimosis, and a bad
attitude. Generally, once the fur ring is removed and the penis gently cleansed, no further
treatment is necessary. However, in a breeding situation, “stud” chinchillas may
repeatedly get fur rings. Whether they get these directly from the fur of the female, or
from having the penis extruded from the prepuce so often (through either excitement, or
exhaustion and the lack of strength to retract it) is not known. This may vary with the
individual. In any case, chinchilla breeders should be aware of the potential, and check
their males on a regular basis.
Restraint and Handling
Proper restraint of a chinchilla can be a challenge. Being a prey species, excessive
restraint and struggling can cause epinephrine release, further debilitating a sick
chinchilla. In addition, chinchillas can undergo “fur slip” where excessive restraint leads
to the loss of fur over the area being grasped. This is an effective mechanism in the wild
for escaping predators but is not conducive to instilling client confidence in the
examination room.
More dominant or aggressive chinchillas, especially intact males, may jump onto
the side of the cage and spray urine outward at an approaching human. Keeping your
mouth closed helps minimize the effect of this behavior.
Nervous chinchillas prefer to be held close to the body with their heads tucked
into the holder’s axilla. The scooping technique works well. Lift the chinchilla with one
hand supporting its caudal ventrum and tail, and the other over its head while directing it
towards your axilla. It can hide its face while you auscultate and palpate. It is best to sit
on the floor both for stability and for insurance in case the chinchilla manages to jump
from your grasp. Juggling a chinchilla in mid-air, attempting to prevent a fractured tibia
while trying not to grab it too tightly and cause premature baldness (fur slip), is not a
situation into which one wishes to be placed. (Author’s note: Although the
aforementioned recommendation of sitting on the floor with these fractious patients is
still my preference, it admittedly becomes more difficult to return to a standing position
as age and girth increase incrementally ((the author’s, not the chinchilla’s)). Luckily,
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client sympathy usually prevails, and they will either leave the exam room while you
have some dignity remaining, and/or call for a forklift).
With extremely fractious chinchillas, or in those in which venipuncture,
radiographs or other procedures that require patient compliance are planned, the use of
isoflurane may be less stressful for all parties than manual restraint. Induction may be via
the use of a large dog cone face mask as chamber, or alternatively (consuming more
isoflurane, but generally being less stressful), a small chamber induction unit can be
utilized, giving new meaning to the phrase “Tupperware Party”.
If only a mild degree of sedation is needed, or if the chinchilla appears to be
stressed due to pain, buprenorphine and butorphanol both work well at dosages
equivalent to those used for postoperative analgesia.
Hands on Physical Examination
The extremely thick fur of the chinchilla can disguise weight loss (much as do the
feathers on a bird). Palpation of the thorax and ribs will reveal emaciation when present.
Most adult chinchillas weigh between 400 – 700 grams, although healthy, sexually active
males may normally weigh less than 400grams. The male chinchilla is normally smaller
than the female.
Chinchillas often object to having their temperature taken (normal rectal
temperature is about 99 – 102 F, 37-30 degrees C). The smaller, digital thermometers are
more readily accepted for obvious dimensional reasons. It may seem basic, but make
certain you are placing the thermometer into the correct orifice. Female chinchillas have a
very small anogenital distance and will object violently (and rightfully so) if one attempts
to take a vaginal temperature. Female chinchillas have a membrane that restricts the
opening of the vagina except during breeding. Attempts to place a thermometer into this
locale may result in prodding of the urethral opening, which is not a healthy or
comfortable proposition. Young male chinchillas may not have discernable testes,
whereas adult males’ testicles are usually visible. The penis lies a considerable distance
craniad from the rectum. Check to confirm the reported sex of a chinchilla during the PE.
These are often incorrectly identified when sold (hence the high number of female
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chinchillas named “Brutus”). While you are examining the anogenital area also check for
fecal impaction in or around the rectum.
The pads of the feet should be examined for irritation or urine scald. Fortunately,
unlike guinea pigs and hedgehogs, chinchilla toenails are not as likely to grow into the
footpads. Chinchillas are more active, less heavy-bodied, and possess greater ground
clearance than these species, thereby reducing the incidence of contact related problems
such as bumblefoot, scrotal dermatitis, urine scald, etc.
Hydration should be assessed, utilizing several of the same criteria as in other
small animals. Elasticity of the skin is easiest to measure. Dehydrated chinchillas will
usually also have dull, dry, sunken appearing eyes. During the oral examination,
evaluation of the mucous membrane will also help detect any dehydration. As was stated
earlier, the occurrence of clinically observable dehydration in a chinchilla is a serious
condition, necessitating immediate attention.
One of the more difficult and most necessary parts of the PE on a chinchilla is
visualization of the teeth - both the incisors and the molars. In young chinchillas an oral
examination will often reveal primary incisor malocclusion that is either congenital or
traumatic in origin. If the anorexia and malnutrition have not persisted for a prolonged
period, incisor trimming will often allow the chinchilla to return rapidly to eating. Older
chinchillas that present with signs of malocclusion, including incisor overgrowth, often
have a primary molar malocclusion that has developed over time due to inappropriate
diet, insufficient opportunity to chew, or ill health.2,3,4,5 Trimming the incisors may
slightly and temporarily improve the chinchilla’s ability to prehense and chew, but it is
necessary to examine and correct any existing molar malocclusion, and evaluate
secondary soft tissue trauma that may have occurred due to the sharp points of the
deviated molars. Many adult chinchillas present for incisor overgrowth and have the
incisors trimmed without the molars being examined.
Various devices for examination of the molars in awake and anesthetized
chinchillas have been advocated. An otoscope may be used but the light source is often
weak and the security of the fit between the cone and the scope is not dependable. Also,
as the chinchilla bites down on the plastic cone, it becomes mangled and develops sharp
edges. It soon becomes unusable for placement into the mouth of another chinchilla or
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rabbit or even for use in the ear canals of dogs. Several companies now manufacture
devises based on pediatric nasal speculums that serve well in the oral examination. We
have found that a pediatric laryngoscope is an excellent tool for molar visualization while
awake, and for molar trimming under anesthesia. A device that allows excellent
visualization but can be a bit difficult to assemble and insert, is available though.
The oral examination is often the last part of the PE, since the animal may object
strenuously, making a calm physical examination impossible. If pathology is found in the
molars there is little reason to continue the oral examination awake. Often the oral
mucosa is ulcerated and painful. Visualization and correction of the molar malocclusion
and other oral lesions can be completed later when the chinchilla is under anesthesia.
Auscultation of the lungs and heart in a chinchilla can be difficult due to the rapid
respiration (normal 40-80/min.) and the small area occupied by the thoracic cavity. The
heart rate can vary tremendously with the state of excitation, generally ranging between
180-350 beats/minute. Cardiac problems are not as prevalent in chinchillas as in other
exotic species discussed in this article. Although reportedly susceptible to Pasteurella sp.,
as in rabbits, and Bordetella sp., (more commonly noted for causing disease in guinea
pigs), these pathogens are not frequently the cause of respiratory disease in chinchillas.
Treatment of pneumonia is beyond the scope of this article. Be aware that although
nebulization with antibiotics can be a life saving part of the treatment protocol, one must
be sure that the nebulizer unit does not get excessively warm and exacerbate respiratory
distress.
As with many of our exotics, husbandry is often the most significant factor in
medical problems of chinchillas. An accurate, complete history and a through physical
examination are vital to the development of a diagnostic and therapeutic protocol.
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Prairie Dogs (Cyonomys ludovicianus)
This is one of the more frustrating species presented to the exotic practitioner.
Very little concrete data is present on the proper husbandry of prairie dogs. Diet is similar
to that of the chinchilla, with a higher percentage of greens tolerated and enjoyed by this
species. In nature, prairie dogs forage for various grasses surrounding their burrows.
Respiratory disease
With or without severe obesity, respiratory problems are not only common, but
are the rule in prairie dogs kept in captivity. Whether humidity has a causative role in the
multiple respiratory syndromes is not documented. In nature, prairie dogs are diurnal
desert dwellers, so they are exposed to a dry environment on a daily basis. However, their
extensive burrows contain a higher moisture content. This has led to disagreement
between practitioners as to whether low or high humidity is a potentially exacerbating
factor. In recent years, the role of the tooth root hyperplasia has been demonstrated to
cause occlusion of the nasal passages. It is proposed that this occurs in response to the
concussive force that occurs when P.D. chew repeatedly on wire or hard plastic cages.
Several surgical procedures can be utilized to attempt to alleviate the respiratory distress.
Excision of the incisors can be accomplished in some cases in the same manor as it is
performed in rabbits. The size, density and irregularity of the roots, however, make this a
more difficult procedure. A temporary improvement may be obtained by placing a stent
on the dorsal aspect of the nose, permitting intake of air proximal to the occlusion caused
by the roots of the incisors. In this author’s experience, these stents eventually adhere to
the underlying tissue and patency is lost.
Prevention of this syndrome is difficult, but if prairie dogs are to be kept in
captivity, they should be supplied with sufficient material to chew, including wood,
cardboard, and vast amounts of hay. The ethics of keeping these animals in captivity is
compounded by the impending endangered status of the black-tail prairie dogs. Due to
poisoning by farmers and ranchers, and vacuuming of the young from burrows in the
wild, the population has been decimated. The species has been recognized as endangered
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in 2000, but apparently due to a lack of funding for enactment and enforcement of this
status, they have not to date been added to the protected list.
Cardiomyopathy is also noted in a percentage of captive prairie dogs after two to
three years of age (Crispen Spencer, DVM, ACVR, personal communication), and the
possibility of a nutritional origin for this condition has been postulated, but not identified.
Cardiomyopathy will present with clinical signs similar to primary respiratory disease.
If the diet of a prairie dog is not limited and exercise not encouraged, obesity is
inevitable. This may either cause or add to respiratory impairment.
Prairie dogs need environmental enrichment. Provide material in which to
burrow, in an effort to substitute for their dens in the wild. Avoid any shavings or
materials that produce dust, as this may add to the potential for respiratory disease.
Clinical techniques
Physical examination
Some prairie dogs remain tame with frequent handling, and can be thoroughly
examined awake. However, they are able to inflict a painful bite, so choose your
candidates for handling carefully. Stroking of the gums and cheeks is enjoyed by tame
prairie dogs, but once again, it would not be advisable if the temperament of the animal is
questionable. A thorough oral examination should be performed, especially if respiratory
signs are present, since oral, pharyngeal, and hard palate neoplasia are common.
Venipuncture
Even tame prairie dogs are reticent to allow venipuncture while awake. They
tolerate isoflurane masking or chamber induction well, and jugular sticks are usually best,
though the excessive fat on the neck can make this procedure more difficult than in other
species. While the prairie dog is under sedation, be sure to check the toenails, which can
overgrow quite severely. Hepatic problems are common, including hepatic lipidosis and
hepatic adenocarcinoma. Serum chemistries and CBCs can be utilized to aid in
determining any underlying disease. Hepatic biopsies are often indicated following either
radiographic evidence of hepatomegaly, or hepatic enzyme elevation. As in chinchillas
and guinea pigs, the thoracic cavity is relatively small compared to the abdominal cavity.
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Be cautious with obese patients, and elevate the head and thorax to aid in respiration
while under anesthesia. Malocclusion can occur in this species, but does not seem to be
as common as in rabbits and chinchillas.
Anal Sac Triad
Prairie dogs possess a pronounced trio of scent gland papilla that often appear
distended when the animal is restrained. To date, this author has experienced no clinical
problems with these anal structures.
Note: This article relates to captive prairie dogs. Wild caught prairie dogs are potential
reservoirs of Yersinia pseudotuberculosis, and Yersinia pestis. With the zoonotic
potential of wild prairie dogs, clients should be discouraged from keeping these as pets.
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Rats – Quick Facts
Mammary tumors
1. Common, usually benign but often recurrent
2. Most are fibroadenomas
3. Decreased incidence and recurrence has been observed clinically in
ovariohysterctomized female rats.
4. Male rats may also get these mammary related growths.
5.
Although often large in size, resection (often w/ concurrent OVH) is
accomplished successfully by many practitioners.
6. In lieu of OVH, Depo-Lupron has been shown to be efficacious in the
prevention of mammary fibroadenomas in female rats. (Breast Cancer
Res Treat 1999 Nov;58(2):131-6 Prevention of rat mammary
carcinoma utilizing leuprolide as an equivalent to oophorectomy, )
7. Perioperative care, with an emphasis on prevention of hypothermia,
and hemostasis, is critical.
Respiratory Disease
1. Chronic and recurrent respiratory disease is common in rats.
2. Etiologic agents include: Mycoplasma and probably multiple viruses.
3. Due to anatomic damage, “cures” are the exception rather than the
rule.
4. Mycoplasma may be difficult to isolate via culture, but a trial of
antibiotics for this organism is often rewarding.
5. Antimicrobials often recommended for this include doxycycline,
enrofloxacin, chloramphenicol , and tylosin (via nebulization). Care
must be used with macrolide antibiotics to avoid dysbiosis.
6. Cultures will often reveal opportunistic organisms such as E. Coli,
Pseudomonas, Enterobacter sp.. These may also require antimicrobial
therapy.
7. Reports of the response to nebulization therapy and the addition of
bronchodilators are mixed
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8. Improved husbandry, with emphasis on increased ventilation, adequate
humidity, and decreased particulate matter (dust) may improve or limit
the respiratory compromise.
9. Obesity may cause or exacerbate both mammary tumors and
respiratory disease, and is a very common problem in pet rats.
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Hamsters – Quick facts
1. Skin disease, including demodectic mange, is very common in hamsters, and
seems to be particularly common in the Russian (Syrian) hamsters. Demodectic
mange may present as mild alopecia to severe alopecia with pronounced
seborrhea.
2. Other differentials for alopecia in hamsters commonly include Cushing’s Disease
and neoplasia (often cutaneous lymphoma). Skin biopsy is a good diagnostic tool.
3. Sebaceous glands on the lateral flank of hamsters are normal but look like
melanomas. Check the contralateral side prior to declaring these a mass and
recommending resection.
4. Hamsters are prone to obesity.
5. Redundant skin over the nape requires “double scruffing” to prevent the hamster
from turning and biting the handler. Obviously, if the hamster is tame this type of
hold should not and need not be used.
6. Hamsters can escape, be dropped and injured, or reflectively “flung” by the
handler when they bite. It is best to handle them at a low height in a small, secure
area.
7. Cheek pouch abscesses are common, and may be associated with swelling in the
equivalent facial area, and sometimes overgrown incisors. Flushing, debridement,
and parenteral AB will be effective in some cases.
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Notes
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References
1) Hillyer EV, Quesenberry KE: Ferrets, Rabbits, and Rodents. Philadelphia, PA, W.B.
Sanders Co. 1997.
2) Harkness JE, Wagner JE: The Biology and Medicine of Rabbits and Rodents 3rd Ed.
Philadelphia, PA, Lea & Febiger.
3) Harcourt-Brown F, Textbook of Rabbit Medicine, Elsevier, Oxford, UK, 2002.
4) Johnson-Delaney CA: Exotic Companion Medicine Handbook for Veterinarians.
Lake Worth, FL, Wingers Publishing Inc.
5) Brown SA, Clinical Techniques in Rabbits, in Seminars in Avian and Exotic Pet
Medicine Vol. 6, No. 2 April 1997: p 86- 95.
6) Lightfoot TL, Bartlett LW, Harrison G, Exotic Companion Animal Surgeries, (CDROM) Winger’s Publishing Co., Lake Worth, Florida, 1999.
8) Harrenstien L: Gastrointestinal Diseases of Pet Rabbits, in Seminars in Avian and
Exotic Pet Medicine Vol 8, No2, April 1999, p 83-89.
9) Bennett A, PMMA Beads, in Exotic Veterinary Magazine, 1:4, 1999, p 1.
(Portions reprinted with permission of Exotic Veterinary Seminars, copyright 1998)
Recommended Reading
1) Vet Clinics of North American – Exotic Animal Practice, 1999-2003
2) Ferret Medicine and Disease (Fox) 2nd ed.
3) AEMV (Association of Exotic Mammal Veterinarians) Client handouts and
Clinician information Compendium for Members.
4) BSVMS Exotic Animal Manual 2002.
5) Seminars in Avian and Exotic Pet Medicine, 1998-2003.
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Additional references available upon request
Please feel free to e-mail or call me regarding any questions you may have
following this Seminar. To assure that your e-mail is not deleted, please place “First
Step” in the subject area of any e-mail message. [email protected]
Thank you for attending and for your participation. I know I will have learned
from you, ( I always do…) and I hope this material is helpful to you in your practice.
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