Canine Bacterial Pyoderma

Development of pyoderma occurs in 2 stages. Firstly the pathogen colonises areas of the body surface. It may then become a surface pyoderma. The 2 most important of these surface pyodermas are skin fold pyodermas (intertrigo) and pyotraumatic dermatitis. The second phase occurs when the most superficial layer of the skin (the stratum corneum) is invaded to cause impetigo and/or invasion of the hair follicles causing folliculitis. The latter 2 are classified as superficial pyoderma. When the infected hair follicle ruptures, the infection spreads into the dermis (furunculosis) or spreads more deeply along tissue planes (cellulitis). The latter 2 are termed deep pyodermas. Resolution depends on the non-specific defenses (neutrophils and macrophages) and on the specific defenses (cell mediated immunity and antibodies). Resolution is accompanied by an inflammatory response, which is responsible for the clinical signs of pyoderma.