Sexually transmitted venereal tumors are actually about two thousand years old, started with a wolf or coyote, and now lives as an asexual entity that can reproduce on its own, but has to be transmitted through sex. These tumors can affect both males and females of any age or breed, but most often found in stray dogs that mate often with more than one dog. It is a common and serious type of tumor that is distributed all over the world, mostly seen in the United States, Caribbean, Africa, and Asia. The tumors will multiply and then go into a type of remission in approximately four to eight months. Unfortunately, that is plenty of time to spread the disease to many other dogs. Sexually transmitted venereal tumors are not often seen in purebred dogs because these dogs are not allowed to breed with more than one dog and their mates are screened for all types of diseases.

Sexually transmitted venereal tumors, which are also called canine transmissible venereal sarcoma (CTVS), are on the outside of your dog’s genitalia and transferred to other dogs during sex. The actual cells inside the tumors are contagious and not the dog itself. In fact, the cells within the tumors found on your dog will actually be the cells from the carrier dog, which is unusual because other cancers are normally caused by the dog’s own cells. While this is a serious disease, it is rarely fatal unless your dog is not in good health to begin with.

The main symptom of sexually transmitted venereal tumors is the presence of small, hard nodules or sores in your dog’s genital area (at the base of the penis in males and the entrance of the vaginal canal in females). Other symptoms that have been reported are:

The tumors multiply and increase in size (up to 11cm) and ulcerate within the first several months. Although it is rare, there have been some cases reported that the tumors spread to the dog’s internal organs (i.e. heart, lungs, stomach) if left untreated.

The cause of sexually transmitted venereal tumors is direct contact with the cells from a tumor in a dog that is not in remission. It is contagious through sex and oral contact within the first four to eight months after transmission.

The veterinarian will need to know if your dog has been allowed to be outside for a lengthy amount of time or around other dogs, such as at a dog park or doggie day care. You will need to provide all of your dog’s medical history including any recent illnesses or injuries, vaccination records, changes in behavior, and when the symptoms first started. Your veterinarian will also need to do a comprehensive physical exam, checking the entire body for signs of tumors or swelling. The exam will also include weight, body temperature, blood pressure, and heart rate.

After the physical examination, the veterinarian will have to do some tests, such as a cytological smear test of any lesions that are bleeding, biopsy of one of the nodules, fine needle biopsy of lymph nodes, CBC (complete blood count), blood chemistry panel, urinalysis, and possibly a semen sample if your dog is a male. The cytology tests are examined under a microscope to get a quick preliminary diagnosis done to get treatment started as early as possible. Other tests that the veterinarian may need to perform are abdominal and chest radiographs (x-rays), ultrasound, CT scan, and an MRI.

In most cases, your veterinarian will want to surgically remove the tumor or tumors and have them tested at a lab to see if they are malignant or benign. If the tumor is found to be malignant, the veterinarian may want to do do chemotherapy and radiation treatments. This is not always the best choice for these cancers because they will sometimes go into remission on their own in four to eight months. In some cases, the veterinarian may try a medication called vincristine sulfate in male dogs if they are to be used for breeding purposes.

The prognosis for your dog depends on the amount of tumors, length of time taken to get treatment, and if the tumor is malignant. If your dog is healthy and the tumor is not malignant, the prognosis is good and there should not be any residual health problems. However, it the tumor is malignant, your dog’s prognosis depends on the effects of the treatment. Sometimes radiation and chemotherapy treatments are too hard on the dog’s system and it may not be suggested if the dog is already in poor health. Be sure to follow up with your veterinarian as directed.