This article explains how TVT transmits: https://www.marvistavet.com/transmissible-venereal-tumor.pml
We cannot ascertain, though, if the parts (in red), about TVT not being malignant and can spontaneously regress on its own, are true. Some vets do not agree with these parts. We asked our vets and have learnt that this article is probably referring to the TVT in the USA, which could be slightly different from the one we have over here.
And we also found this to counter the above:
TVTs develop from skin histiocytes. TVTs are malignant (cancerous) tumors. Different from other cancers, TVTs can spread between dogs. It is sexually transmitted through direct skin-to-skin contact with the tumor that results in cancer cells being transplanted from dog to dog.
Although this cancer may disappear on its own (spontaneous regression) due to an immune system response, this is extremely rare. TVTs usually continue to grow and can become increasingly bothersome without treatment.
Hence, it is best to get it treated.
The article is below. It just goes to show that we should not believe everything we read, even though the source appears to be a credible one and is written by veterinarians. The best is to check with your own veterinarian whom you trust. Also, a disease that manifests in our region may have a different “version” in another region.
| Imagine a tumor that can be transmitted by touch. For dogs, this is not a matter of imagination; the Transmissible Venereal Tumor has been described since 1876 and is not unusual where stray dogs roam free and have contact with one another. The tumor is found in both male and female dogs. Transmission is by simple physical contact between an existing tumor on one dog and abraded mucous membrane (oral, genital, nasal etc.) on another. It is most commonly spread during mating but can also be spread during routine sniffing or other contact. In most cases, tumor growth is found on the genitals but it can also just as easily emerge on noses, mouths, anal areas, and other anatomical sites.
The Transmissible Venereal Tumor, also more succinctly called the “TVT”, may be visible as an external fleshy growth or may simply present as genital bleeding (eventually the tumor will become eroded on the surface and bleed). As mentioned, the tumor is common where there are large numbers of roaming dogs or in shelter situations. In most cases the tumor is not malignant and simply grows and bleeds at a local site eventually being rejected by the patient’s immune system; however, resolution of the tumor can take over 9 months which is a long time for a patient to bear a bloody infected growth. In approximately 10% of patients, the tumor actually does spread malignantly in a cancerous fashion though this is more likely in dogs that have an immunological compromise (young age, poor general health, concurrent other disease). Because of the long time to resolve and the potential for spread, treatment is generally recommended over simply allowing the tumor to regress. Strangely, the tumor cells are not the patient’s own cells transformed into cancer cells. This is not a matter of a virus being transmitted which causes normal cells to become cancerous. The TVT is actually a tumor that grafts itself from one dog’s body onto another dog’s body. Unlike the host’s normal cells, TVT cells have a completely different number of chromosomes and do not originate from the host at all. Developing a TVT might analogous to getting bitten by a mosquito and the few mosquito cells left behind actually trying to grow a new mosquito on one’s body.
Diagnosis is made either by biopsy (taking a small piece of tumor tissue for analysis) or by cytology (obtaining a smear of the tumor’s cells and looking at it under a microscope as shown above). The TVT is one of several tumors classified as a “Round Cell Tumor.” Biopsy samples are more accurate whereas a smear exam might only indicate that the growth in question is a Round Cell Tumor without being more specific. TREATMENT Treatment of the Transmissible Venereal Tumor is straightforward and generally very rewarding:
Page last updated: 8/5/2023 |
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Here’s what we understand based on this article and consultation with vets.
- The TVT is transmitted by direct mucosal contact (touch). This means it is normally transmitted through intercourse and other mucosal contact – vaginal/penile/ lips/muzzle region with the tumour.
- The contact may be with the tumour itself or even with the blood from the tumour.
- If an open wound is in contact with the tumour or blood from the tumour, transmission may happen as well.
- Transmission through contact with the urine of an infected dog is not likely. We were asked this question so we are clarifying it.
- TVT is often assumed to be malignant and treated with chemo drugs. The chances of recovery is good if treatment starts early and is completed.
- Untreated TVT will continue to grow as the chances of regression is extremely rare. If it grows too big and blocks the urinary tract, this leads to severe urinary problems and even death.
- We have also encountered the odd cases where two spayed female dogs present with TVT a year of after being spayed. This incidence may be due to the TVT lying dormant in the dog and only manifesting when the immunity is compromised, or it could also be the rare chance of new mucosal contact by the dogs (even mating due to hormonal changes or hierarchical challenges) after being spayed.
Therefore if a TVT dog is spotted free roaming on the streets, it is vital that the dog be caught immediately and sent for treatment. Otherwise, the infection could spread easily to other healthy dogs if they mate with the infected dog or even if they were to sniff at or lick the blood that is secreted from the tumour. This is why some dogs are infected on the nose. One of the clear symptoms of TVT is bleeding at the vaginal area, but is not limited to this. TVT has been found on other anatomical sites such as the paws and legs.
Neutering will significantly reduce the chances of a dog contracting TVT. However, sometimes the cells are already dormant in the dog and may take months or years before it manifests externally.