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, Transmissible Venereal Tumor, Sticker Tumor, Infectious Sarcoma
Causes 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.
Symptoms 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
Diagnosis Biopsy is necessary for diagnosis.
Treatment Treatment of the TVT
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.