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January 2006

Cat Skin: Cowpox Dermatitis

Animal: Cat, 12 yr old, neutered male, Domestic Short Hair.

Organ: Skin

Submission history: Three week history of ‘cellulitis’ under chin which was non responsive to broad-spectrum antibiosis. Further ulcerative lesions developed, after one week of initial onset of clinical signs, to the left hind leg and the dorsum. Ulcerative lesions also present on oral cavity, primarily on the tongue. Biopsy was performed on dorsal lesions and submitted for histological examination.

Cowpox virus is member of the orthopoxvirus group in the family Poxviridae. Reservoir hosts in Europe include voles, wood mice, ground squirrels and gerbils. Cutaneous clinical signs include an initial erythematous ulcerated plaque or macule (often head, neck and forelimbs). Secondary lesions can develop within 10 days following viraemia. Ulcers within the oral cavity can occur. Development of a systemic infection is rare but can include a necrotising bronchointerstitial pneumonia. Classical lesions include highly acidophilic, variably sized, predominantly single and globular intracytoplasmic inclusion bodies. Cutaneous lesions usually are centrally ulcerative and display peripheral epidermal hyperplasia and ballooning of keratinocytes.

Diagnosis: Cowpox dermatitis.

Photo by: Trevor Whitbread & Richard Fox