Canine transmissible venereal tumor

[3] Although the genome of a CTVT is derived from an individual canid (specifically from a population of Native American dogs with coyote contribution),[4][5] it is now essentially living as a unicellular, asexually reproducing (but sexually transmitted) pathogen.

[6] Sequence analysis of the genome suggests it diverged from canids over 6,000 years ago; possibly much earlier.

Signs of genital TVT include a discharge from the prepuce and in some cases urinary retention caused by blockage of the urethra.

Metastasis occurs to regional lymph nodes,[citation needed] but can also be seen in the skin, brain, eye, liver, spleen, testicle, rectum and muscle.

Although direct contact is generally not a highly efficient mode of transfer, CTVTs take advantage of the popular sire effect of domestic dogs.

A single male can produce dozens of litters over his lifetime, allowing the tumor to affect many more females than it could if a monogamous species were the host.

Understanding the epidemiology of CTVTs could provide insights for populations that may experience CTVT exposure and information about disease prevalence.

[11] All tumor cells of this type of cancer share extremely similar genetic code, often if not always unrelated to the DNA of their host.

[20] The tumor, when treated with the chemotherapy drug vincristine, regresses as the host immune system is activated.