Sexually Transmitted Tumors in Dogs

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Transmissible Venereal Tumor in Dogs

A transmissible venereal tumor, or TVT, is a naturally occurring tumor that is sexually transmitted from one dog to another. A high number of cases tend to be seen in large cities and temperate areas. TVT is usually seen in young, intact (non-neutered) dogs.

Symptoms and Types

You may observe a red, tumorous mass bulging out of the surface membrane of the vagina, or on the penis. The tissue mass may break off upon manipulation. Blood drops may also be observed dripping from the vagina or penile foreskin. The dog will usually lick the affected area with frequency.


This condition is the result of direct contact with tumor cells from a diseased animal. It is transmitted through the act of sex, and can also be transmitted by oral contact. Intact, free roaming dogs are at greater risk of acquiring and spreading this disease.


Your attending veterinarian will need a complete health history, with as much information as possible regarding when the symptoms began, how much freedom your dog has to roam freely or whether there are other dogs that roam the area, if you have been attempting to breed your dog, etc.

The physical examination will focus especially on your dog's genital organs. A tissue sample of the mass will need to be taken for biopsy, and fluid samples will be taken for the standard laboratory tests, including the complete blood count, biochemistry profile and urinalysis. The results of these tests are usually within normal ranges, but in some cases blood cells or abnormal cancer cells may be found in the urine sample.

This type of tumor rarely spreads to other locations, but your doctor will need to visually confirm that it is not a malignant form of cancer. Visual diagnostics will include chest and abdominal X-rays to determine if there has been metastasis, and what stage it is in, if cancer is present. Your veterinarian will also palpate the lymph nodes of the affected area to determine how much the lymph nodes are reacting to the abnormality, an important distinguishing factor when cancerous cells are present.

A sample of lymph fluid will be sent to laboratory for further evaluation, to determine if cancerous cells are in the sample. The presence of cancerous cells in the lymph nodes is often a strong indication that the tumor is not benign. Treatment will be based on the results of these tests.

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