Todayโs path rounds are on ๐ญ๐ซ๐๐ง๐ฌ๐ฆ๐ข๐ฌ๐ฌ๐ข๐๐ฅ๐ ๐ฏ๐๐ง๐๐ซ๐๐๐ฅ ๐ญ๐ฎ๐ฆ๐จ๐ฎ๐ซ๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐ซ๐๐ง๐ฌ๐ฆ๐ข๐ฌ๐ฌ๐ข๐๐ฅ๐ ๐ฏ๐๐ง๐๐ซ๐๐๐ฅ ๐ญ๐ฎ๐ฆ๐จ๐ฎ๐ซ๐ฌ (TVTs) are one of the few known types of tumour that can be spread by contact, like an infectious disease. This is an extremely rare feature for a tumour to have!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
Dogs get this tumour.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
As mentioned, this tumour is spread from dog to dog, typically during coitus.
This tumour has a particularly unique behaviour, even among infectious tumours. TVTs are actually a ๐ฑ๐๐ง๐จ๐ ๐ซ๐๐๐ญ, meaning a graft of tissue from another species. Genetic evaluation of the tumour cells revealed that these cells actually contain ๐๐ ๐๐ก๐ซ๐จ๐ฆ๐จ๐ฌ๐จ๐ฆ๐๐ฌ, rather than the typical 78 chromosomes that dogs have.
Further research showed that the genetic composition of these 59 chromosomes is most similar to wolf DNAโฆ wolves that lived about ๐๐ ๐๐๐ ๐ฒ๐๐๐ซ๐ฌ ๐๐ ๐จ, that is! This means that this tumour has essentially been โlivingโ as its own type of pathogen since it was originally spread from ancient canid populations to domestic dog species.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
This tumour typically occurs on the genitalia, where it grows rapidly and is susceptible to bleeding. This usually doesnโt bother the animalโs day to day life too much, but urination may become painful for these animals.
More problematic is when the tumour accidentally becomes implanted somewhere else on the dog. Common areas are the skin, mouth or nose. The tumour may also metastasize to internal organs, including the brain. These metastases can cause a wide range of effects depending on the tissue involved!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
TVTs can be diagnosed by a ๐๐ข๐ง๐ ๐ง๐๐๐๐ฅ๐ ๐๐ฌ๐ฉ๐ข๐ซ๐๐ญ๐, where a needle is used to sample the cells to look at them under the microscope. They can also be diagnosed on a biopsy.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
TVTs are typically treated with chemotherapy or radiation therapy. These tumours typically have a good prognosis, unless metastases are involved.
๐๐ก๐จ๐ญ๐จ๐ฌ
1-3) Examples of TVT on the penis of dogs.
4) TVT enlarging the vulva.
5) An example of TVT on the skin.
6) An example of TVT on the tissues around the eye! Poor pup 
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 3. Sixth Edition.
Kutzler M. Canine transmissible venereal tumour. Merck Veterinary Manual 2020.
Photos 1-6 ยฉ Noahโs Arkive contributor Barretto/Araujo, Kesdangsakonwut, King, Domingo licensed under CC BY-SA 4.0.
