Cat scratch‐induced P asteurella multocida necrotizing cellulitis in a dog

Background In humans, rapidly developing P asteurella multocida cellulitis after a cat scratch or bite is a well‐known entity that sometimes progresses to necrotizing fasciitis and can be fatal. Case report A 3‐year‐old female spayed whippet dog developed ecchymosis, swelling and pain within 24 h of being scratched by a cat on the ventral thorax. Over the following days, while being treated only with pain medications, the lesions rapidly progressed into haemorrhagic bullae with expanding skin necrosis. A heavy growth of P . multocida was seen on bacterial cultures, and histological examination showed marked, suppurative panniculitis with necrosis of the epidermis, dermis and panniculus. Special histological stains highlighted a moderate amount of Gram‐negative coccobacilli admixed with inflammatory cells. Complete resolution was achieved with surgical debridement, skin grafting and intravenous antibiotic treatment. Positive bacterial culture for P . multocida , in conjunction with the history, clinical findings, histology results and the rapid response to therapy, strongly supports a diagnosis of P . multocida necrotizing cellulitis. Conclusions and clinical importance Complications of cat bite‐associated P . multocida infections in humans are well known. To the authors' knowledge, this is the first documentation of P . multocida necrotizing cellulitis in a dog following a cat scratch wound. This case highlights the rapidity and severity of P . multocida cellulitis, if not recognized and treated early. Veterinarians should include P . multocida in the differential diagnosis of any local wound infection following a cat scratch.