Pathological and immunohistochemical studies on rare cases of primary extra-genital transmissible venereal tumours in the mammary gland

Transmissible venereal tumours (TVT) are normally seen on the genitalia of both male and female dogs, and at times may be observed on extra-genital sites such as lips, oral mucosa, and peritoneum, or in organs such as the tonsils, eye, liver, spleen, kidney, lung, and musculature. The present communication deals with two rare cases of primary extragenital TVT involving the mammary glands of dogs and their pathology and immunohistochemistry. The study indicated that apart from routinely used markers such as vimentin, p53, PCNA, Ki-67 and c-myc, the oncogenes Rb and cyclin D1 proved to be novel markers of TVT in dogs. To the authors’ knowledge, this is the first report of extra-genital mammary TVT in canines.