Transmissible Venereal Tumors In Dogs

It is generally understood that cancer is not a communicable disease, so some might find it surprising that there are rare exceptions in the animal world. Transmissible venereal tumors (TVTs) are a type of cancer that can be spread between dogs, particularly (but not exclusively) through coitus. Fortunately, TVT in dogs is both uncommon and often curable when it does occur.

Both male and female dogs of any age and any breed can develop a transmissible venereal tumor, typically in the genital area, however it appears more commonly in younger dogs that roam. Still, this cancer is rare in the U.S because so many dogs are neutered. It is not the neutering per se that diminishes the chances of a dog getting these tumors but rather that fact that being neutered means they are less likely to participate in sexual activity. That said, transmissibility can occur in other ways, too:

  • A dog can have a nasal tumor that is diagnosed as a TVT, likely from sniffing an infected dog long enough to transplant a tumor.
  • Puppies that suckle from an infected mother can develop a tumor in the mouth/lips area.


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Signs Of A Canine Transmissible Venereal Tumor

Since a tumor is an abnormal growth, a TVT may present as a lump or bump in the penile or prepucial area of a male dog or the vulva region or in the vulva of a female dog. A dog will typically lick the affected area especially as the mass progresses in size. There may  be bleeding, oozing or discharge. If the tumor is big enough to cause a urethral obstruction, a dog may have difficulty urinating. For a puppy with a tumor on or near its mouth, suckling might be challenging.  If the cancer is in the nasal cavity, nasal discharge, sneezing and congestion my result.

Workup & Diagnosis

If you suspect that your dog has a cancerous tumor, your veterinarian likely will perform a series of diagnostic procedures to determine the type, the stage if the tumor is malignant, and the course of action. The workup usually begins with a physical examination, a CBC (completely blood count), a chemistry profile, a urinalysis and checking for enlarged lymph nodes. Depending on the location of the tumor and the suspected type of cancer, the veterinarian also may order chest X-rays and/or an abdominal ultrasound to check for potential spread.

In the case of a suspected transmissible venereal tumor in dogs, sometimes an aspiration cytology can help in diagnosis.  As other tumors can present in these same areas as a TVT, a biopsy may be used to rule out whether the mass is a mast cell tumor or a sarcoma so there can be a higher level of certainty about the type of tumor which would then dictate treatment.

Treatment Options & Prognosis

Transmissible venereal tumors in dogs are treatable and very rarely metastasize (spread) to the lymph nodes. Treatment options include:


The treatment of choice is typically a chemotherapy drug called vincristine. Weekly intravenous injections are administered on an outpatient basis, and usually fewer than 10 visits are needed. On occasion, vincristine does not provide a cure, however, and a different chemo drug could be prescribed in these cases.


If chemotherapy is not effective or cannot be used for another reason, radiation is a good option. There are two primary types: conventionally fractionated radiation therapy (CFRT) and Stereotactic Radiation (SRS/SRT). SRS/SRT therapy entails the tumor being targeted with high doses of radiation that are designed to kill or at least slow the growth rates of cancerous cells while eliminating or minimizing the damage to surrounding healthy tissue. CFRT uses lower dosages of radiation but requires a higher number of treatments (typically 16 to 18), while Stereotactic Radiation — the more innovative option — typically consists of just one to three treatments. Since dogs must be anesthetized for radiation, the reduction in number of treatments with Stereotactic Radiation can be extremely beneficial. Radiation can be curative for TVT. At PetCure Oncology, our team is highly qualified to provide Stereotactic Radiation therapy.


In many cases for TVTs, surgery is not the first line of therapy as wide, clean margins often cannot be obtained on the penis, in the vulvar region or in the nasal cavity.  There are occasional instances, however, that surgery may be beneficial.  This should be discussed with your veterinarian on a case-by-case basis.

No treatment

If chemotherapy and radiation are both declined and TVTs are untreated, they will continue to grow. In such instances, a dog’s quality of life and comfort levels should be monitored, and further decisions should be based on those observations.

Find A PetCure Oncology Location Near You

At PetCure Oncology, we provide innovative treatments for dogs with TVTs and many other types of cancer. We sincerely care about your dog’s well-being. Our team’s mission is to do everything possible to extend your time together while also providing your beloved pet with good quality of life. For more information about PetCure Oncology and our treatment options, find a location near you today.

Types of Cancers in Dogs

If your dog is displaying any symptoms of cancer or has been diagnosed with cancer, sort below by cancer type or tumor location to learn more about the most common types of cancer in dogs and available treatment options. Click on the links for more specific information on treatment and real patient stories.


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