Venereal Tumor - Symptoms and Treatment

95% of cases of venereal tumors in dogs are cured thanks to chemotherapy.
Venereal Tumor - Symptoms and Treatment

Last update: 05 September, 2019

Pets often get sick and some of those illnesses are serious. It’s for this reason that you should about some of them, and know what to do if your pet suffers from one. One of these conditions is known as a venereal tumor and today we’d like to tell you all about it.

What’s a venereal tumor?

This is a tumor that mainly affects dogs and, unlike other known tissue masses, this one is transmitted via physical contact. The disease was discovered over a hundred years ago, when it was discussed in the scientific documents of the time.

However, it didn’t appear in the old world until the twentieth century. It wasn’t until the end of this century that it began to appear as an epidemic that increasingly affects more and more dogs.

Generally, this disease occurs in places where the weather is mild to warm and in dogs who are sexually active. It particularly affects those who are homeless or who live in shelters etc. This is perhaps because the disease is venereal. It’s easier to catch it in such places, mainly because they’re with other dogs that could be infected there.

Nobody knows the exact cause of a venereal tumor. Some scientists say that it’s due to a retroviral cause. Others claim that it’s because of the amplification of a proto-oncogene. What we do know for sure is that this disease always spreads venereally, and that in many cases it occurs through a tumor cell transplant.

For example, once a tumor passes from one host to another, it takes from two to six months to incubate. A small mass will appear during this period, revealing the existence of a tumor.

Symptoms of a venereal tumor

A dog with a venereal tumor.
The dogs who contract a venereal tumor are usually sexually active and spend a lot of time on the street. The symptoms begin with a small swelling in the genital area, which in males gives rise to continuous small hemorrhages coming from their penis.

In females, however, a fleshiness usually appears on the vulva and it also causes vaginal bleeding. Keep in mind that these are not the only visible forms of this tumor.

For example, they can also occur intranasally, or in the oral cavity, the eyes, or the skin. A doctor may perform cytopathology to try to identify if a tumor is venereal.

In this procedure, a lab technician collects a sample of the tumor and then analyzes it. Even though this is not usually the type of tumor that metastasizes, he will also examine the lymph nodes. This is to confirm whether or not they’re affected by it as well.

Treatment for a venereal tumor

A sedated dog.

Stay calm if you think that your dog might have one of these tumors or if your vet already confirmed the diagnosis. Chemotherapy is very effective in 95% of cases and the chances of recovery are very high.

Vincristine is the most commonly used medication and a vet will administer it intravenously once a week for four to six weeks. However, there are reports of side effects after the use of this medication and they could cause some discomfort for your pet. Some of them are vomiting, neuritis, leukopenia, and bone marrow depression.

How to prevent transmission

If you plan to breed your dog, then make sure that the other animal isn’t a carrier of the disease. Evaluate their genital area, above all. Keep in mind also that it’s possible for a dog to have had a venereal tumor, and then if they show no symptoms of recurrence for at least a year there’ll be no reason to worry about it.

As you can see, a venereal tumor is not as dangerous as it sounds. There is, in fact, a high probability of a good recovery. So, relax, and trust your veterinarian and the treatment they prescribe.


All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.


  • Sota D, Amico D. Tumor venéreo transmisible en el perro. Cienc Vet. 2004;
  • Vergaray NZM. Frecuencia del tumor venéreo transmisible en caninos. Laboratorio de Histología, Embriología y Patología Veterinaria-Facultad de Medicina Veterinaria-Universidad Nacional Mayor de San Marcos. 2006.
  • De La Cruz SM, Quijano-Hernández IA, Del Ángel-Caraza J, Castañeda JSM, Victoria-Mora JM, Barbosa-Mireles MA. Respuesta del Tumor Venéreo Transmisible Canino a Presentaciones de Vincristina de Patente y Genérica. Rev Investig Vet del Peru. 2015;

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.