Affects: Dogs
A canine transmissible venereal tumor (CTVT), also known as a transmissible venereal tumor (TVT), canine transmissible venereal sarcoma (CTVS), sticker tumor or infectious sarcoma, is a histiocytic tumor of the external genitalia of domestic dogs and other canines, and is transmitted from animal to animal during mating. It is one of only three known transmissible cancers in mammals; the others are devil facial tumor disease, a cancer which occurs in Tasmanian devils, and contagious reticulum cell sarcoma of the Syrian hamster.
The tumor cells are themselves the infectious agents, and the tumors that form are not genetically related to the host dog. Although the genome of a CTVT is derived from an individual canid (specifically from a population of Native American dogs with coyote contribution), it is now essentially living as a unicellular, asexually reproducing (but sexually transmitted) pathogen. Sequence analysis of the genome suggests it diverged over 6,000 years ago; possibly much earlier. Estimates from 2015 date its time of origin to about 11,000 years ago. However, the most recent common ancestor of extant tumors is more recent: it probably originated 200 to 2,500 years ago.
Canine TVTs were initially described by Russian veterinarian M.A. Novinsky (1841–1914) in 1876, when he demonstrated that the tumor could be transplanted from one dog to another by infecting them with tumor cells.
Signs And Symptoms: In male dogs, the tumor affects the penis and sheath. In female dogs, it affects the vulva. Rarely, the mouth or nose are affected. The tumor often has a cauliflower-like appearance. Signs of genital TVT include a discharge from the prepuce and in some cases urinary retention caused by blockage of the urethra. Signs of a nasal TVT include nasal fistulae, nosebleeds and other nasal discharge, facial swelling, and enlargement of the submandibular lymph nodes.
Treatment Method: The tumor, when treated with the chemotherapy drug vincristine, regresses as the host immune system is activated. CCL5 may play an important role in the immune response.
Treatment: Surgery may be difficult due to the location of these tumors. Surgery alone often leads to recurrence. Chemotherapy is very effective for TVTs. The prognosis for complete remission with chemotherapy is excellent. The most common chemotherapy agents used are vincristine, vinblastine, and doxorubicin. Use of autohaemotherapy in treatment of TVTs also showed promising results in many cases. Radiotherapy may be required if chemotherapy does not work.