Pyoderma — bacterial infection of the skin — is one of the most common dermatological conditions affecting dogs. Ranging from superficial surface infections to deep, severe tissue involvement, pyoderma causes significant discomfort and welfare compromise. Understanding its causes and management enables effective prevention and treatment.
Classification
- Surface pyoderma: Confined to skin surface (hot spots/acute moist dermatitis, skin fold pyoderma) — involves epidermis only
- Superficial pyoderma: Involves epidermis and follicle (impetigo in puppies, superficial bacterial folliculitis) — most common type in adult dogs
- Deep pyoderma: Extends below epidermis into dermis and subcutaneous tissue; most painful, most welfare-significant
Causative Organisms
Staphylococcus pseudintermedius (formerly S. intermedius) is responsible for the vast majority of canine pyoderma. In normal skin, this organism is a commensal; disease occurs when skin barrier function is compromised. Methicillin-resistant S. pseudintermedius (MRSP) is an emerging concern in dogs requiring referral antibiogram guidance.
Underlying Causes
Pyoderma in adult dogs is almost always secondary to an underlying condition that has compromised skin barrier function or immune response:
- Atopic dermatitis (environmental allergy) — the most common underlying cause
- Food allergy
- Ectoparasites — particularly Demodex (demodicosis)
- Hypothyroidism or hyperadrenocorticism
- Skin fold anatomy (Bulldogs, Shar Peis, Pugs)
- Immunosuppressive medications
Clinical Signs and Welfare Impact
Superficial pyoderma presents with papules, pustules, epidermal collarettes, and crusting — pruritic and uncomfortable. Deep pyoderma causes nodules, draining tracts, haemorrhagic crusting, and severe pain — dogs may resent handling of affected areas and show behavioural changes from chronic discomfort.
Treatment
Topical therapy: Chlorhexidine shampoos, sprays, and wipes provide antimicrobial action and are appropriate for superficial infections — reducing antibiotic use. Frequency: twice weekly shampoos for 3–4 weeks.
Systemic antibiotics: Required for deep pyoderma or extensive superficial disease. Choice should be based on culture and sensitivity where possible. Duration: minimum 3–4 weeks for superficial, 6–8+ weeks for deep pyoderma. Courses should always be completed.
Underlying cause treatment: Without addressing the underlying condition, recurrence is expected. Allergy management, parasite control, and endocrine treatment are concurrent priorities.
Welfare and Monitoring
Pain assessment is important in deep pyoderma — analgesic support (NSAIDs) should accompany antibiotic treatment in painful cases. Regular rechecks during treatment allow dose adjustment and ensure resolution before antibiotics are stopped. Untreated or under-treated pyoderma progresses, causing increasing pain and tissue damage — prompt effective treatment is an ethical obligation in veterinary care.