Eosinophilic dermatitis with edema in nine dogs, compared with eosinophilic cellulitis in humans.

A unique eosinophilic dermatitis with edema in dogs is characterized by extremely erythematous coalescing macules and plaques with associated edema, and is similar to eosinophilic cellulitis (Wells' syndrome) in humans. Histopathologic features include a profound eosinophilic dermal infiltrate, focal areas of collagen fiber degeneration surrounded by eosinophils (flame figures), dilated vessels, and dermal edema. Etiopathogenesis is unknown, but a hypersensitivity reaction to medications, arthropod bites, or other foreign antigens is suspected.