Canine Health Menu

Infectious Sarcoma

Issue Description
A histiocytic tumor of the dog and other canids that mainly affects the external genitalia, and is transmitted from animal to animal during copulation.
Other Names
Canine Transmissible Venereal Tumor, CTVT, TVT, Sticker Tumor, Transmissible Venereal Tumor

TVT is most commonly seen in sexually active dogs in tropical and subtropical climates. The disease is spread when dogs mate, and it can even be transmitted to other canine species, such as foxes and coyotes. Spontaneous regression of the tumor can occur, probably due to a response from the immune system. TVT undergoes a predictable cycle: the initial growth phase of four to six months (P phase), a stable phase, and a regression phase (R phase), although not all TVTs will regress. The tumor does not often metastasize (occurring in about 5 percent of cases), except in puppies and immunocompromised dogs. Metastasis is most commonly to regional lymph nodes, but can also be seen in the skin, brain, eye, liver, spleen, testicle, and muscle.

In male dogs, the tumor affects the penis or prepuce. In females, it affects the vagina or labia. 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, from blockage of the urethra. Signs of nasal TVT include oronasal fistulae, nosebleeds and other nasal discharge, facial swelling, and enlargement of the submandibular lymph nodes.

Biopsy is necessary for diagnosis.

Treatment of the Infectious Sarcoma is straightforward:

Surgery is not as effective as one would expect. In one study of 70 dogs, 22% had recurrence within 5 months. If a tumor is surgically removed and found to be a Transmissible Veneral Tumor, one of the other treatment methods should ensue.

Vincristine is a chemotherapy agent which must be delivered intravenously. Special IV catheters or butterfly units are placed to deliver the drug as any spillage of the drug into the tissue surrounding the vein results in a painful tissue slough (i.e. a chemical burn occurs). This, however, is the only serious risk in this treatment and as long as proper IV materials are used this complication is rare. The TVT responds after only one treatment or two but generally 3-6 weekly treatments are administered to ensure a cure.

External beam radiation is very effective in curing the TVT but is very expensive and not readily available. If one is near a facility, however, this may be a good option.