Clinical Exposures: Canine transmissible venereal tumor: The cytologic clues
Jun 01, 2008
A 3-year-old castrated male Labrador retriever with a history of blood dripping from its penis was referred to the Foster Hospital for Small Animals at the Cummings School of Veterinary Medicine at Tufts University. The dog had been adopted from a breed rescue group about six weeks before presentation. Before being acquired by the rescue group, the dog had lived in Texas and Tennessee. Bloody penile discharge had been noted since the adoption, although the new owners reported that it had initially seemed to resolve without any intervention.
Canine transmissible venereal tumor, also called Sticker's sarcoma, is a naturally occurring, horizontally transmitted round cell tumor found in domestic dogs and potentially other canids such as gray wolves and coyotes.1,2 Although there have been reports of this tumor in most parts of the world, a high incidence seems to exist in temperate climates. The tumor is seen most commonly in young, sexually active, intact dogs allowed to roam freely (including stray dogs).1-3 These tumors are usually spread during coitus or other social behaviors such as sniffing and licking.1,2 Thus, the typical locations of these tumors are the external genitalia and the nasal and oral cavities.1-3 Other less common locations include the anal mucosa and the skin and subcutaneous areas.3,4 A recent report of a multicentric, extragenital, cutaneous canine transmissible venereal tumor in a sexually immature 11-month-old virgin female mixed-breed dog suggests that transmissible venereal tumor cells can be inoculated into puppy skin lesions by the mother during social interactions such as grooming and other mothering behavior.4 Transmissible venereal tumor metastasis has been seen involving the lymph nodes, skin, eyes, liver, musculature, abdominal viscera, lungs, and brain.3-5