They don’t need mood lighting or smooth jazz because . . . well . . . they’re dogs. And as dogs do when given the right opportunity, and access to other canines, they mate. Which is why you may have heard recently of outbreaks of canine transmissible venereal tumors (CTVT)–particularly if you adopt from shelters.
But this isn’t a recent problem. CTVT, according to Elizabeth Murchison of the University of Cambridge and her team who have completed the largest study of the disease to date, has been around for over 6,000 years. It has been traced to Asia and unlike most cancerous tumors, it didn’t die with its owner. It found a way to live on through sexual transmission. It was eventually passed on to the Americas by dogs brought here by colonists, and the American version of the disease has become the dominant strain. CTVT is more prominent in tropical or subtropical climates, and in the U.S. is seen more in southern regions.
You may be aware of cancers that are connected to sexual behavior. Cervical cancer in humans, for example, can be spread by sexual contact. The cancer itself, however, is not the culprit in cervical cancer; it is rather the human papilloma virus that is transmitted and can cause a higher likelihood of cervical cancer. In the case of CTVT, the cancer itself is transmitted from dog to dog through direct contact with the cauliflower-like tumors that characterize the disease. Infection is not limited to the genitals of infected animals. CTVT can be communicated to the skin, nasal tissue, the mouth, and, in rare cases, the eyes.
Dogs who have contracted CTVT may excessively lick the infected area, and you may notice bleeding or bruising in the affected area. Where visible, you might see nodules that continue to grow and that may ulcerate or bleed. Keep in mind, however, that the disease can proliferate in hard to see areas.
A Wagging Tale
This is a story with a happy ending. If you are someone considering adopting a pet from a shelter or fostering from rescue programs, don’t let fears of CTVT stop you because the disease is imminently treatable. If you suspect an animal may be infected, ask your vet to take cell samples, which should indicate whether they carry CTVT or not.
Traditional treatments have included surgical excision of tumors, chemotherapy, and radiation therapy. Because the disease is spread through contact with the CTVT lesion, effective treatment can eliminate spread from animal to animal and decrease the probability of recurrence. Here are a few things to consider about each type of treatment”
- Surgical excision: is no longer the treatment of choice because of the high recurrence rate of between 18% and 60%.
- Chemotherapy: the standard treatment today is a six-week course of one dose of vincristine sulfate per week administered by IV. This therapy has shown a high probability of 100% regression, which means no recurrence and no transmission to other dogs. Factors that complicate the likelihood of success are age, immunosuppression, age, and recent pregnancy.
- Radiation therapy: because chemotherapy has proven so effective, radiation is only used in the most resistant cases or when the disease has metastasized. It has shown to be efficacious in these rare cases.
The good news, ultimately, is that, unlike other cancers, CTVT doesn’t seem to build resistance to drug therapy. Therefore, it is more easily treated. Indeed, in the study conducted by Murchison, almost all of the 546 dogs sampled recovered with treatment, including those whose infections had metastasized.
Don’t Roll Over
There’s no need to fear the outcome of adopting a dog with CTVT. The prognosis is excellent with chemotherapy and the likelihood of metastasizing is only around 5%. Even if you have other dogs in your household, as long as they are kept separate until the disease is in remission, they should be safe. And once treatment is complete, there is low probability of reinfection (unless they come into contact with another dog who has CTVT) and a high likelihood of living out a normal life.
You may, of course, hear chemotherapy and think cost prohibitive, but vincristine is a very cost effective drug with prices ranging on average from a 3-week course for around $300 to a 5-week course of around $350. The main factors of concern around chemotherapy are probably dealing with side effects more than cost. Veterinarians indicate that the most common side effects of treatment are diarrhea, vomiting, and loss of appetite. They usually occur within 24 to 72 hours of treatment.
So if you’ve seen that dog you love, don’t let the possibility of CTVT stop you from taking them home. A little time, a small investment, and some tender loving care should soon have them in top shape, ready to be that best friend you’ve been looking for.