Canine Transmissible Venereal Tumor: Prevalence & Distribution

Canine transmissible venereal tumor (CTVT) is a type of cancer transmitted from dog to dog during coitus. The tumors are most often associated with the external genitalia in male and female dogs. Evidence suggests CTVT originated several thousand years ago but global spread has occurred more recently.

The authors analyzed CTVT literature and used a questionnaire from 645 veterinarians and animal health workers in 109 countries to assess the global distribution and prevalence of CTVT. CTVT was found to be endemic in at least 90 countries, with worldwide distribution. CTVT has a prevalence rate of at least 1% in many countries in South and Central America, Africa, and Asia. It is only endemic in remote indigenous communities in the United States and Australia. The United Kingdom eradicated CTVT inadvertently when it imposed stricter dog control laws. These laws reduced the population of free-roaming dogs, thought to be a reservoir for CTVT. Spaying and neutering were also found to be associated with decreased CTVT rates. No association was found with gender or with other infectious diseases. Treatment using vincristine alone or in conjunction with surgery, doxorubicin, or radiotherapy was most common. The authors conclude that this study can be used to develop more effective control measures to reduce CTVT rates around the world.

While CTVT is more common in some countries and more frequent in intact dogs, it is important to note that there is no definitive pattern of occurrence. CTVT should be on the list of differentials for intact and neutered dogs, anywhere in the world when clinical signs are compatible. It remains a highly treatable disease with an excellent prognosis. This paper suffers from a lack of objective response criteria for the survey, lack of definitive diagnosis, and low numbers of responders (veterinary and non!) in multiple countries. Other factors to consider that may have influenced results are the prevalence of diseased stray dogs (ie, not evaluated by veterinarians), and availability of veterinary care in different countries or areas.—Cecilia Robat, DVM, DACVIM (Oncology)