Transmissible venereal tumor of the uterine stump following successful chemotherapy in a 5-year-old mixed-breed dog.

A 5-year-old spayed female mixed-breed dog was referred to the Atlantic Veterinary College (Charlottetown, Prince Edward Island) because of a 7-month history of intermittent pink, mucoid, vulvar discharge. The dog was imported from the Bahamas at 3.5 y of age and had a history of transmissible venereal tumor (TVT) of the vulva that was successfully treated with a course of vincristine chemotherapy. Complete remission was achieved with a disease-free interval of 6 mo before clinical signs recurred. Abdominal ultrasound and CT scan identified a large caudal abdominal mass thought to arise from the uterine stump. An exploratory laparotomy was performed and the mass grossly excised. Histopathology was consistent with a poorly differentiated round cell tumor, and immunohistochemical analysis confirmed TVT as the most likely diagnosis. No further treatment was carried out. Repeat abdominal ultrasound at 4 mo after surgery showed no evidence of mass recurrence. At 8 mo after surgery, the dog was reported to be doing well clinically. Key clinical message: Transmissible venereal tumor should be considered as a differential diagnosis for masses arising from the deep genital tissues of dogs in cases where there is a history of previous TVT. Transmissible venereal tumor should be considered even in dogs that have had complete resolution of a primary mass after chemotherapy.