Download canine superficial pyoderma care pathway

CANINE SUPERFICIAL
PYODERMA CARE PATHWAY
PREMISE
Canine superficial pyoderma is one of the most common skin disorders treated by veterinarians. Superficial pyoderma is
defined as a superficial bacterial infection of the epidermis and hair follicle, and is usually secondary to allergic, parasitic,
endocrine, immune-mediated, conformational or keratinization (seborrheic) disorders.
The following factors have been proposed as reasons why dogs are especially prone to the development of pyoderma,
compared to their human owners: their hair follicles lack a lipid plug; they possess a thin stratum corneum; they have a high
skin pH; they have decreased cutaneous defensins in cases of pyoderma secondary to atopic dermatitis; and they are often
colonized with potentially pathogenic staphylococci. Impetigo, superficial folliculitis and exfoliative superficial pyoderma
(formerly superficial spreading pyoderma) are examples of this type of infection. Staphylococcus pseudintermedius is the
most common causative organism, with S. schleiferi and S. aureus less commonly isolated.
Staphylococcal methicillin or multidrug resistance can occur, especially in patients with recurrent infections and after multiple
courses of antibiotics. The best treatment outcomes are associated with early recognition and management of the underlying
cause of the pyoderma, along with aggressive systemic and topical therapy using products that result in assured compliance.
This approach gives us the best chance of avoiding long-term complications such as resistant infections and chronic inflammatory changes in the skin, which make successful long-term control difficult. When managing patients with recurrent pyoderma,
a proactive preventive approach is preferred to avoid frequent relapses and exposure to multiple courses of antibiotics.
PREVENTION
The best way to prevent the clinical signs of superficial pyoderma is to diagnose and treat the underlying disease. Primary
cases of pyoderma are rare, and with control of the underlying disease, secondary infections are unlikely to recur. Maintaining
excellent year-round parasite control from a young age for all pets in the household is important. Keeping the pet’s skin
clean and healthy (especially in skin folds) and its hair coat un-matted through regular grooming and bathing is helpful
in decreasing the likelihood of bacterial overgrowth and infection. Frequent use of antibacterial shampoos, sprays, wipes and
mousses is useful in preventing recurrence of infection. Management of acute pruritus that can lead to self-trauma, disruption
of the skin barrier and bacterial overcolonization is important. Since allergies are one of the most common underlying causes
of recurrent superficial pyoderma, one preventive measure might be to select pets that are not genetically predisposed to the
development of allergies.
Pet owners should be appropriately counseled to recognize signs of the disorder such as redness, bumps, “pimples,” sores,
hair loss and odor, especially in commonly affected areas such as skin folds, ventral neck, axillae, groin, ventral abdomen,
interdigital spaces and perineal area. The full extent and severity of skin lesions may be difficult for owners to appreciate
in a longhaired pet, until the hair is clipped.
The consequences of infection in the dog should be discussed, including the uncommon possibility of zoonotic disease
transmission in immunosuppressed, very young or elderly people in the household, and the importance of good hand
hygiene and infection control when handling the affected dog (www.wormsandgermsblog.com).
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CANINE SUPERFICIAL
PYODERMA CARE PATHWAY
DETECTION
The diagnosis of pyoderma involves evaluation of history and physical examination findings, and cytologic examination
of skin surface or lesion exudates. In some situations, such as with previous antibiotic therapy or lack of response to rational
therapy, additional diagnostic steps such as culture and sensitivity or skin biopsy may be needed.
Superficial pyoderma can occur in any breed of dog but is more commonly diagnosed in breeds prone to atopic dermatitis
(AD). Dogs with AD have decreased epidermal barrier function and increased staphylococcal colonization and adherence of
lesional and non-lesional skin compared to normal dogs (McEwan, 2006). Staphylococci also can trigger IgE production and
worsen pruritus in these dogs.
Clinical signs include erythema, follicular pustules, papules, crusts, scaling, epidermal collarettes and alopecia. Short-coated
breeds often have “moth-eaten” patchy alopecia on the trunk with disheveled tufts of raised hairs, subtle circular to
semicircular scales and collarettes. Long-coated breeds may present with large areas of alopecia with rapidly expanding
collarettes that may or may not be inflamed. Most commonly affected areas in dogs are skin folds, axillae, groin, ventral
neck, ventral abdomen and interdigital spaces. The full extent of skin lesions may be difficult to appreciate until the hair is
clipped. Pruritus ranges from absent to severe. Chronically infected dogs may manifest lichenification, hyperpigmentation
and excoriations in affected areas.
Skin scrapings to rule out demodicosis and fungal culture to rule out dermatophytosis should be considered, since both
Demodex mites and dermatophyte fungi target the hair follicles. It is particularly important to perform a fungal culture
if there are multiple animals involved, cytologies are negative for bacteria, or there is a failure to respond to antibiotic
therapy. Cytologic examination of impression smears of exudate from papules, pustules, crusts or collarettes supports the
diagnosis and typically shows large collections of cocci, usually in pairs, tetrads or clumps. In a true infection, one should see
intracellular bacterial cocci and degenerative neutrophils; surface overcolonization (bacterial overgrowth syndrome, or BOGS)
shows increased numbers of cocci with few to no neutrophils.
A methicillin-resistant staphylococcal (MRS) infection should be suspected, and cultures should be performed prior to
antibiotic therapy, when the following risk factors are present: cocci on cytology and poor response to cephalosporins,
potentiated penicillins, and fluoroquinolones; recent antibiotic use in the last 6–12 months; multiple veterinary visits in the
last six months, non-healing postsurgical infections; owner works in a healthcare field; MRS infection in household (person or
pet); recent human or pet hospitalization; or pet is a therapy dog (Weese, 2010, 2012; vanDuijkeren, 2011). Pets with known
or suspected MRS infections should be isolated from other pets in the hospital, taken directly to an exam room that can be
decontaminated and provided with their own individual pack of diagnostic equipment, which will then be suitably disinfected
or discarded. Good hand hygiene and environmental cleaning (regular disinfection of otoscope cones, flea combs, clipper
blades, thermometers, stethoscopes, microscope knobs, scales, doorknobs, phones, computer keyboards and accessories,
waiting-room chairs) should be mandatory in the veterinary hospital to prevent spread of MRS infection to pets, people or
fomites (www.wormsandgermsblog.com; www.bsava.com/Resources/MRSA.aspx).
In nonresponsive cases, skin biopsy for histopathologic assessment may be performed to rule out other causes; findings
in cases of superficial pyoderma may include subcorneal or follicular pustules, folliculitis, and perifolliculitis; bacteria may be
seen in crusts or follicular keratin.
Differential diagnoses include demodicosis, dermatophytosis, yeast dermatitis, pemphigus foliaceus, drug eruption and
sebaceous adenitis.
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CANINE SUPERFICIAL
PYODERMA CARE PATHWAY
TREATMENT
Most superficial pyodermas are treated with a combination of antibiotic and topical therapy. Since most of these pyodermas
are associated with underlying problems (e.g., allergies), it is important to set owner expectations that if those underlying
problems are not adequately addressed, then recurrence of the pyoderma should be anticipated at some point. A separate
issue is that antibiotic resistance is becoming more commonplace, and that if an empirically chosen, appropriate antibiotic
fails to resolve the pyoderma initially, it is important not to escalate therapy, but to further clarify the situation with bacterial
culture and susceptibility testing.
The initial antibiotic treatment should be a 14-day course, with reexamination at two weeks to assess response and decide
whether an additional course of treatment is indicated. Concurrent glucocorticoid therapy should be avoided during this
initial period if possible, since it might be suppressing the innate immune response and can confound assessment. If there
has been little or no response to a sensibly selected antibiotic during this initial period, then the reasons need to be investigated,
rather than attempting therapy with a perceived “stronger” antibiotic. In fact, an MRS infection is also unlikely to be
responsive to fluoroquinolones, so guessing is not appropriate at this stage.
When choosing a systemic antibiotic for empirical use in the treatment of pyoderma, several important factors need to be
considered. Therapy should be initiated with an antibiotic with known efficacy against greater than 90% of the isolates of
S. pseudintermedius, which, by far, is the most common microbe associated with canine pyoderma. In addition, first-line
therapy for superficial pyoderma should typically involve a beta-lactam antibiotic (potentiated penicillin or cephalosporin).
If the pyoderma does not respond to the empirical selection of an appropriate beta-lactam, then culture and susceptibility
testing is indicated rather than reaching for a “stronger” antibiotic class.
The safety of the drug chosen should also be considered, based on published reports of side effects and on clinical
experience, such as knowing which antibiotics are most likely to cause adverse events.
Since owner compliance is a major concern, ease of use is important in the antibiotic selection process. An injectable
antibiotic provides convenience and guarantees adherence to the treatment protocol, relieving the owner of at least one
at-home responsibility. The next most convenient options are appropriate antibiotics that can be administered once daily,
followed by those that are to be given every 12 hours.
Owners are often asked to medicate their pets at home. Owner lifestyle, daily schedule and expertise/experience in administrating medications (pilling, applying topicals and shampooing ) need to be explored using open-ended questions in order
to come up with a realistic treatment plan that has the best chance of success.
Topical therapy is also an important component of managing superficial pyoderma. Because of microbial population
dynamics, bathing is initially needed two to three times a week with products (e.g., chlorhexidine, benzoyl peroxide) that
should have a 10-minute contact time with the skin before being rinsed off. In between baths, antiseptic sprays, wipes and
mousses can be applied one to three times daily directly to affected areas. Very localized areas of infection can be treated
with antibacterial creams, ointments, lotions or gels (e.g., mupirocin, silver sulfadiazine, sodium fusidate). In some cases,
especially with resistant infections, sodium hypochlorite (household bleach) can be applied as sprays or soaks, after having
been diluted to one ounce of household bleach per gallon of water (roughly 7.5 mL per liter). Higher concentrations are not
necessary and may cause skin irritation and drying.
With chronic recurrence of superficial pyoderma, immunomodulation with a staphylococcal bacterin can be used as an
adjunctive treatment to stimulate the dog’s immune system against staphylococcal antigens, and
may result in fewer episodes of recurrence (DeBoer, 1990).
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CANINE SUPERFICIAL
PYODERMA CARE PATHWAY
TREATMENT (cont.)
TIPS FOR SUCCESS IN TREATING SUPERFICIAL PYODERMA
• If the infection recurs within days of discontinuing antibiotics, the treatment course was not long enough. If the
infection recurs weeks or months later, the underlying cause was not controlled.
• Identify and develop an action plan to manage the underlying cause(s) of pyoderma, such as atopic dermatitis,
food allergy and flea allergy.
• Incorporate aggressive topical therapy into initial and long-term treatment plans.
• P
erform bacterial culture and susceptibility testing in patients that do not respond to empirical therapy or with a
history of previous antibiotic use.
• A
void concurrent glucocorticoid therapy, if possible.
• S
et owner expectations appropriately by emphasizing the importance of compliance with medications and the
need for a stepwise diagnostic workup in recurrent or nonresponsive cases.
• F
ocus on treatment plans that are realistic for the pet owner and likely to succeed.
• E
ducate your staff and pet owners on the importance of good hand and environmental hygiene when treating
dogs with pyoderma in the hospital and at home.
• C
onsider referral to a dermatologist for resistant or recurrent cases.
COMMENTS — Canine superficial pyoderma is one of the most frequent skin diseases encountered in veterinary practice.
While most cases can be satisfactorily managed with the treatments mentioned here, it is often worthwhile to involve a
veterinary dermatologist in the case, especially if the pet is not responding to treatment as anticipated, a resistant infection
is cultured or suspected, or uncontrolled allergies or other underlying diseases are complicating management.
RECOMMENDED READING — Bacterial skin diseases. In: Miller WH, Griffin CE, Campbell KL, eds. Small Animal
Dermatology. 7th ed. St. Louis: Saunders; 2013:184-195.
Weese JS et al. Methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in veterinary medicine.
Vet Microbiol. 2010;140:418-429.
Weese JS et al. Factors associated with methicillin-resistant versus methicillin-susceptible Staphylococcus pseudintermedius
infection in dogs. JAVMA. 2012;240(12):1450-1455.
vanDuijkeren E et al. Review on methicillin-resistant Staphylococcus pseudintermedius. J Antimicrob Chemother. 2011;
66:2705-2714.
McEwan NA et al. Adherence by Staphylococcus intermedius to canine corneocytes: a preliminary study comparing
noninflamed and inflamed atopic canine skin. Vet Dermatol. 2006;17:151-154.
DeBoer DJ et al. Evaluation of a commercial staphylococcal bacterin for management of idiopathic recurrent superficial
pyoderma in dogs. Am J Vet Res. 1990;51(4):636-639.
CONTRIBUTORS — Michele Rosenbaum, VMD, DACVD; Lowell Ackerman, DVM, DACVD, MBA, MPA;
Valerie Fadok, DVM, PhD, DACVD
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CANINE SUPERFICIAL
PYODERMA IN-HOSPITAL
ACTION PLAN
STEPS:
1. Perform:
• S
kin scrapings and cytology to support diagnosis and rule out demodicosis and yeast dermatitis. Cocci are
anticipated and may be phagocytosed within neutrophils.
• Bacterial culture and susceptibility testing in patients with a history of multiple antibiotic courses or with
nonresponsive or recurrent infections.
• Dermatophyte culture with nonresponsive infections or if multiple animals in the same household are affected.
2. A) If lesions are extensive, administer 14-day course of this systemic antibiotic:
.
B) I f awaiting culture results, use topical therapy until culture results are available. Dog should be bathed two to three
times weekly with this antiseptic shampoo:
Antibacterial mousses, sprays, creams or wipes can be used one to three times daily at home between baths.
.
C) I f lesions are very localized, consider starting this daily topical therapy:
.
Schedule telephone follow-up at one week, and:
If patient is responding as anticipated:
Perform clinical reevaluation at two weeks.
If patient is not responding as anticipated and
compliance has been assured:
If compliance with an oral antibiotic is in question:
Submit appropriate sample for bacterial culture
and susceptibility.
Switch to an appropriate long-acting
injectable antibiotic.
3. DECISION TREE AFTER TWO WEEKS OF THERAPY:
If doing well and all active pyoderma lesions are
clearly resolving or have resolved, and cocci
are no longer evident on cytology:
If improving but some active pyoderma lesions
(e.g., pustules, papules, epidermal collarettes,
crusts) remain and cocci are still seen on cytology:
Discontinue systemic antibiotics and reduce
medicated baths/topicals to once weekly;
schedule telephone follow-up for one week,
and clinical evaluation in two weeks.
Continue systemic antibiotics and twice-weekly
bathing and topicals for another two-week course;
schedule clinical telephone follow-up in one week,
and clinical reevaluation in two weeks.
If skin lesions not improved:
Repeat skin cytology.
If compliance is assured and cocci are seen on cytology:
Perform bacterial culture and susceptibility testing to rule out resistance.
Treat based on culture results, and start daily 3–4% chlorhexidine-based
shampoos, nisin wipes; consider adding sodium hypochlorite (diluted bleach)
baths or sprays while awaiting culture results.
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CANINE SUPERFICIAL
PYODERMA IN-HOSPITAL
ACTION PLAN
STEPS:
4. DECISION TREE AFTER FOUR WEEKS OF THERAPY:
If doing well on initial antibiotic and all pyoderma
lesions have now resolved, and cocci are no longer
evident on cytology:
Discontinue systemic antibiotics and reduce
medicated baths/topicals to once weekly;
schedule telephone follow-up for one week,
and clinical evaluation in two weeks.
If skin problems still persist:
If antibiotic was switched based on culture and
sensitivity, and lesions are resolving but have not
completely resolved:
Continue systemic antibiotics and twice-weekly
bathing and topicals for another two-week course;
schedule clinical telephone follow-up in one week,
and clinical reevaluation in two weeks.
Continue with topical therapy; start exploring in earnest
for underlying problems, or consider referral.
5. DECISION TREE OVER NEXT TWO TO SIX MONTHS:
If pet is doing well:
If pet did well on antibiotics but pyoderma recurs
within days of discontinuation:
Have pet owner continue to monitor for recurrence
of pyoderma; consider long-term preventive
weekly topicals.
If pet did well on antibiotics but pyoderma recurs
within weeks to months after discontinuation:
Perform diagnostic workup for underlying cause
(atopic dermatitis flea allergy, food allergy,
endocrinopathy most common).
Administer antibiotics for a longer duration,
and increase frequency of topicals.
If pyoderma still not responding or recurs frequently,
a multi-drug resistant bacterium is cultured, or
uncontrolled allergy or other underlying disease
is complicating management:
Refer to a specialist.
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CANINE SUPERFICIAL PYODERMA
AT-HOME ACTION PLAN
PET’S NAME:
CURRENT MEDICATIONS:
Most superficial bacterial skin infections are associated with underlying problems, such as allergies, skin folds, parasites
(like fleas, ticks, mites and lice), hormonal imbalances or a weakened immune system. If these problems are not detected
and treated, the infection is likely to return. Also, since antibiotic resistance is becoming more commonplace, it is important
that antibiotics be given on schedule and for the full treatment period.
GO—Your pet is doing well
Your Veterinarian’s Directions:
• Skin infection clearing as anticipated
• Pet tolerating treatments without problems
• I am able to give medications and topicals on time and
without missing any doses
• Itchiness is adequately controlled (<4 on itch scale)
CAUTION—Veterinary assistance might be needed
• Redness of skin • Patches of hair loss, a few bumps or sores, some odor
• Pet might be having a side effect from medication
• I am having some trouble administering the medicines but
have not missed any doses
• Itchiness is increasing (4–7 on itch scale)
Your Veterinarian’s Directions:
STOP—Veterinary attention needed
• Multiple sores, bumps, redness, hair loss, bad skin odor • Pet acting sick (perhaps from medications) • I am unable to give all medications as planned and am
missing doses
• Itchiness is not adequately controlled (>7 on itch scale)
Your Veterinarian’s Directions:
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CANINE SUPERFICIAL PYODERMA
AT-HOME ACTION PLAN
0
No scratching
1
Minimal or occasional scratching
2
Intermittent scratching without discomfort
3
Regular scratching throughout day,
but easily distracted; no real discomfort
4
Moderate scratching, with minimal discomfort;
sleeps through night
5
Moderate regular scratching throughout day and mild
discomfort; sleeps through night
6
Moderate regular scratching and moderate discomfort;
difficult to distract; occasionally scratches at night
7
Moderate regular scratching with considerable discomfort;
itches once or twice every night
8
Severe regular scratching with significant discomfort;
itches several times every night
9
Severe scratching with development of sores;
itches for most of night every night
10
Extreme continuous scratching all day and night
with severe skin damage/sores
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