Transmissible Venereal Tumor – TVT
A Transmissible Venereal Tumor affects the external genitalia of dogs. This contagious disease spreads through mating, sniffing and licking. Usually not malignant, the viable tumor cells attach to mucus membranes or implant in bite wounds. TVT contains fewer chromosomes than normal cells. This disease occurs more commonly in sub-tropical to tropical urban areas, and affects young dogs and more females. A dog that is immune-suppressed, whether because of its young age or a disease, may have a tumor that spreads as cancer to the lymph nodes.
Symptoms and Diagnosis
Symptoms of TVT include a mass on the penis or vagina. Lesions can vary in size and appear as single to multiple cauliflower-shaped. The TVT grows rapidly initially and may appear as a small nodule only 5 mm to a large mass greater than 10 cm. Masses can appear in the adjacent skin, legs, mouth or nose or conjunctival mucosae spread by direct contact. The firm neoplasm, or abnormal mass of tissue, may be fragile in the genital area. The rich blood supply accounts for the pink to red hue. The surface appears ulcerated. As the tumor becomes eroded, blood may drip from the penis or vagina. Other signs include abnormal odor, genital discharge and frequent licking of genitalia.
Diagnosis of TVT includes a history and physical exam. The veterinarian needs to take into account the animal’s sexual history. They physical exam may reveal a reddened tumor covered by a sheath of the penis or vulva. The use of a fine needle aspiration can help determine action. The aspiration of cells from the mass can undergo microscopic examination to determine the tumor type. The aspirates are highly cellular and often bloody. If the aspirate is not conclusive, a biopsy may offer more definitive diagnosis. A complete blood count should appear normal. Though cytology, a smear of the tumor’s cells can be classified as a “Round Cell Tumor.”
Some TVT will disappear without treatment. Treatment of TVT can include chemotherapy with the drug vincristine delivered intravenously. The aim is to slow or stop the growth of cancer cells. Several treatments may follow with the majority of cases cured by the sixth treatment. Removing the small tumors by surgery is possible. However, tumors can recur after surgery. Another option is radiation therapy involving external beam radiation as an effective measure.
Owners need to provide home care and exercise prevention. Monitoring the pet for response to therapy is important. If the pet suffers from loss of appetite, depression, bleeding or abnormal discharge from genitals and a general change in health, the veterinarian should be notified. An Elizabethan collar can save the pet from self-inflicted injuries. Spaying and neutering are other options. Owners should take care that their pet walks with a leash and does not come in contact with unknown dogs. Daily checking of urine is recommended. The prognosis for pets suffering from Transmissible Venereal Tumor is very good.