[Targeting the skin - erythema multiforme in dogs and cats]

This review article will describe the complex nature of erythema multiforme in dogs and cats. The disease pattern will be illustrated in terms of etiology, pathogenesis, clinical signs, diagnostics and therapy. Erythema multiforme is a rare, immune-mediated skin disorder with an acute specific reaction pattern of skin and mucous membranes against different underlying causes. Reported triggering factors include drugs, food ingredients and neoplasias, but viral or bacterial infections and vaccine reactions were also identified. In over 20% of the cases the cause cannot be identified. The German Shepherd dog and Pembroke Welsh Corgi seem to be predisposed. Erythematous macules, slightly elevated and peripherally spreading papules as well as circular to arciform patterns were described frequently in the dog. Wheals, plaques, vesicles and bullae that develop into ulcers, are also seen. Frequently affected areas in the dog are the ventrum, mucocutaneous junctions, mouth, pinnae and foot pads. Histopathological findings include single cell necrosis in all layers of the epidermis with lymphocytic satellitosis and a cell-poor interface dermatitis. Elimination of the causative factors and concurrent symptomatic therapy are recommended. The prognosis varies from guarded to fair, depending on the underlying cause, presenting clinical signs and response to therapy.