Transmissible Venereal Tumor (TVT) is a transmissible cancer in dogs that is usually spread through direct contact with the tumor during mating. Affected dogs have painful masses protruding from the vagina or penis. Sometimes, if a dog sniffs or licks another dog’s tumor, this tumor may be seen on the nose, mouth, eyes, or skin. If your dog is in pain or cannot stop licking the tumor, it may need immediate palliative care.
Symptoms of TVT in Dogs
Tumors on the genital organs may have the following symptoms:
- Gray or pinkish-gray color
- Easily bleeds when touched
- Cauliflower-like appearance
- Firm yet fragile texture (may bleed or tear easily)
- Bleeding from the genital organs
- Licking of the genital organs
- Swelling of the genital organs
When tumors are on the mouth or nose, in addition to nodular masses, you may also observe the following symptoms:
- Nosebleed (epistaxis)
- Sneezing
- Bad breath
- Excessive drooling
- Tooth loss
- Ulcers on the gums or palate
On the skin, these nodules often create open sores and their adjacent lymph nodes may enlarge.
Causes of TVT in Dogs
The transmissible venereal tumor in dogs is usually transmitted during mating. While it is common to see masses on the external genitalia, it can also affect the internal genital organs. The cancer spreads more readily between animals if there are abrasions on the mucosal surface of the genital organs. Note: TVT can also occur in other parts of the body through social behaviors such as licking or sniffing another dog’s tumor. Currently, it is unclear what type of cell TVT originates from. TVT cancer cells have fewer chromosomes (about 59) compared to the dog’s normal cells which have 78 chromosomes. It is believed that this disease first appeared thousands of years ago in wolves or wild dogs. No breed is immune to this disease. Young, sexually active stray dogs are more susceptible to TVT; both genders are affected, but it is more prevalent in female dogs. 
Diagnosis of TVT in Dogs
The veterinarian obtains a diagnostic sample by pressing a slide against the tumor or inserting a needle into the tumor to aspirate some cells and then examining the cells under a microscope. Diagnosis continues by sending a small sample of the tumor to a reference laboratory for microscopic examination. Taking a biopsy sample requires sedation and is typically a minor surgical procedure. In the laboratory, a staining method known as immunohistochemistry may be performed on the tumor samples to determine the aggressiveness of the tumor. In TVT, metastasis (spread to other parts of the body) usually does not occur. In suspicious cases, the veterinarian may biopsy the lymph nodes, perform X-ray of the chest and recommend abdominal ultrasound. Note: TVT can be found worldwide but is more common in urban tropical and subtropical environments.
Treatment of TVT in Dogs
If the tumor is small (less than 2 centimeters in diameter) and in an accessible location, surgical removal of the tumor may be an option. Surgery is generally not feasible for tumors that are large and affect the internal genital organs and/or other areas like inside the nose. For solitary tumors, injection of the chemotherapy drug vincristine into the tumor for one to four sessions, along with interleukin-2 (a compound that mediates interactions between white blood cells), is usually quite effective. Often, a single treatment cycle is sufficient. If the dog shows evidence of metastatic TVT (where the tumor has spread to other parts of the body) or has multiple tumors, the preferred treatment is intravenous vincristine chemotherapy given once a week for up to six weeks. Your dog should be monitored to ensure that it tolerates the chemotherapy (this method may affect its immune system by reducing white blood cell count).
Prognosis and Management of TVT in Dogs
Regardless of where the tumor is located or whether it has metastasized, the prognosis for TVT in healthy dogs is good. Highly aggressive tumors can be fatal, especially if left untreated. Pet guardians should be aware that their dog may develop TVT again after initial treatment. To reduce the likelihood of tumor spread, dog guardians should prevent contact between their pets and stray dogs. Spaying female dogs also decreases the risk of cancer spread. If your dog has TVT, do not allow it to come into contact with other dogs until it has been treated.
Without surgery or medical intervention, most dogs remain ill, and these tumors may become treatment-resistant and spread to more dogs. These tumors are uncomfortable for your dog. The masses often ulcerate and bleed, and the animal may want to lick them. Some pets may need anti-inflammatory medications, such as carprofen, to help reduce pain and inflammation. It may also be necessary to fit them with an Elizabethan collar to keep them from licking the area. The tumor may also cause infections and urinary tract issues in dogs. If you observe concerning symptoms and suspect that your dog may be suffering from TVT, please contact the numbers listed on the website for assistance from our staff at the Central Veterinary Hospital.
Frequently Asked Questions about TVT in Dogs
Is TVT treatable in dogs? Yes, TVT is treatable. Surgery is an option for small, accessible tumors that have not spread. Other TVTs are often treated solely with chemotherapy or radiation therapy, although several treatment sessions may be necessary.
Can dogs transmit TVT to humans? No, TVT does not spread to humans. However, you should wear gloves when touching the tumor.
How long can a dog live with TVT? Most dogs diagnosed with TVT that are treated in the early stages of the disease will have a normal lifespan. Dogs that have the tumor for more than a year may become more resistant to treatment, and their quality of life may be limited.
Source: petmd.com
