First of all, what is pyoderma?
- Pyoderma refers to a pus-producing bacterial infection of the skin and is commonly classified based on the depth of infection.
- Surface Pyoderma – surface inflammation without invasion. Usually is mild and only affects the top layer of skin where there is no hair;
- Superficial Pyoderma – involving the epidermis and intact hair follicles. Superficial bacterial folliculitis can also affect areas of skin with hair and the folds of the skin;
- Deep Pyoderma – able to get into the deeper layers of tissue through a break in the skin that may be caused by scratching.
- Pyotraumatic Dermatitis (usually secondary to allergic dermatitis, especially flea allergy dermatitis);
- Intertrigo knows as Skin-Fold Pyoderma (lip-fold, tail-fold, facial-fold, vulvar-fold, obesity-fold, friction, poor drainage, maceration);
- Mucocutaneous Pyoderma (predominantly seen with lips, perioral skin, nasal planum, eyelids/medial canthi, perivulvar skin, clawbeds and prepuce. Most common with German Shepherds and their crosses).
- Impetigo ( nonfollicular, intraepidermal pustules involving the superficial layers of the dermis);
- Superficial Folliculitis (affects the pstial portion of the hair follicle);
- Superficial Spreading Pyoderma (centrifugally expanding inflammation with characteristic peripheral peeling epidermal collarettes; most commonly observed in Collies, Shelties, and their Crosses.
- Deep Bacterial Folliculitis and Furunculosis leads to a severe granulomatous foreign body response.
- Muzzle Folliculitis and Furunculosis most commonly seen with Bulldogs, Mastiffs, Dobermans.
- Pedal Folliculitis and Furunculosis most common in short-coated breeds. German Shepherd Dog Pyoderma is unique.
- Callus Pyoderma refers to any pressure-point pyoderma.
- Acral Lick Granuloma (ALG).
What are the Causes of Canine Pyoderma?
A visit to the vet is essential, to differentiate from diseases with similar aspects, such as:
- Demodicosis (also called demodectic mange or red mange, is caused by a sensitivity to and overpopulation of Demodex spp. as the host’s immune system is unable to keep the mites under control);
- Superficial folliculitis (affects the upper part of the hair follicle and the skin directly next to the follicle);
- Dermatophytosis (is an infection of the hair, skin, or nails caused by a dermatophyte, which is most commonly of the Trichophyton genus and less commonly of the Microsporum or Epidermophyton);
- Allergy to mosquito bites, fleas and ticks;
- Parasitis Skin Disease: Juvenile/Adult-Onset Demodicosis, Cheyletiella, Otodectes.
- Early scabies;
- Secondary Manifestation of Autoimmune Disease – Pemphigus foliaceus (more likely as a differential diagnosis of bullous impetigo in old dogs), Discoid Lupus Erythematous, Erythema Multiforme, Dermatomyositis.
- Endocrinopathies: Spontaneous/ Iatrogenic Hyperadrenocorticism, Hypothyroidism, Plush-Coated Alopecia.
- Zinc-Response Dermatitis;
- Superficial Necrolytic Dermatitis;
- Food allergy;
- Urine scalding;
- Weakened endocrine system;
- Compromised immune system.
Underlying factors may also include a viral infection such as Canine Distemper inadequate diet and lack of local hygiene (a dirty environment, for example, in poorly managed pet shops with overcrowding, puppies originating from puppy farms and those bred in poor conditions and imported from outside the UK).
- History: absence of prior parasitic treatment, evidence of inadequate diet or a history of living in a known poor environment.
- Physical examination: your vet will do a complete and thorough examination of your dog from head to tail, which will include a detailed check of the skin and coat. We have to look for interfollicular lesions that do not involve the follicles. Folliculitis will involve pustules from which a hair may be seen protruding.
- Cytological examination: Pustule cytology is essential for a correct diagnosis. In microbial culture, the expected result is Staphylococcus, generally, and other microorganisms may occur concurrently. Pricking a pustule and smearing the contents, or by tape stripping of superficial lesions. Diff-Quik staining will demonstrate degenerate neutrophils and intracytoplasmic and extracellular cocci.
A bacterial and fungal culture, chemical panel, complete blood count, urinalysis, and blood glucose level can rule out infection or conditions such as mite infestation. If your vet suspects an underlying illness, x-rays may be needed for verification!
Treatment and prognosis
Shampooing with antibacterial shampoos containing Chlorhexidine (with or without miconazole) or Ethyl lactate should be undertaken three times a week.
Topical Antibiotic Ointment. Some of the topical creams or ointments that your vet may prescribe are mupirocin, neomycin, and polymyxin.
Antibiotics. Cephalosporins should be the first choice for the management of uncomplicated first-occurrence surface, superficial, and deep staphylococcal pyoderma.
- Penicillin, Ampicillin, Amoxicillin, and Tetracycline are poor choices.
- Cephalosporins should be the first choice for the management of uncomplicated first occurrence surface, superficial, and deep staphylococcal pyoderma.
- Safe effective, low levels or resistance, easy-to-administer options via multiple routes.
- Duration of therapy: Superficial Pyoderma 21-30 days, Deep Pyoderma 6-8 weeks.
- For Staph. pyoderma, variable resistance is reported to clindamycin, lincomycin, erythromycin, doxycycline, and potentiated sulfa drugs.
- These antibiotics should not be utilized as first choice options.
- Reserve these antimicrobials with specific culture and susceptibility profiles.
- Amoxicillin-clavulanate – broad spectrum, in vivo effect may not be as good for pyodermas as predicted by culture, excellent choice for bacterial pododermatitis, enterococcus and E. coli infections.
- Floroquinolones should be reserved for gram-negative pathogens, occasional cases of canine MRS pyoderma, excellent for refractory/ recurrent deep pyoderma, excellent tissue penetration.
- Rifampin is effective for Canine MRS pyoderma; should always be used in conjunction with a second antibiotic as resistance develops to Rifampicin very quickly; monitor hepatic enzimes.
- Chloramphenicol is very effective for canine MRS pyoderma; owners must wear gloves – aplastic anemia; most common side effects are loss of appetite, weakness in the rear end.
- Amikacin is also very effective for canine MRS pyoderma, side effects include renal toxicity and ototoxicity.
Fusidic acid (Fucidin) – effective against Staph., Strept., Corynebacterium, and MRSA.
Immunomodulatory therapy for chronic recurrent pyoderma
Immunomodulation should always be utilized as an adjunct to systemic antibacterial and topical therapys. Goal is to reduce the frequency and severity of recurrent infections.
Immunomodulatory therapeutic options:
- Immunoregulin (Propionibacterium acnes) – administered IV every 3-4 days until resolution, maintenance therapy at once monthly.
- Cimetidine (H2-receptor antagonist) therapy (6-10mg/kg PO every 8 hours) may reduce immunosuppression by downregulating supressor T lymphocytes (via inhibition of histamine-influenced immunosuppresion), thus modifying cytokine production.