TVTs: First Year Veterinary Students Share Marley’s Case

By Laura Miller and Anna Merrihew

May 7, 2012

As first-year veterinary students and new HSVMA-RAVS volunteers, we did not know what to expect on our trip to San Carlos, Arizona in March 2012. We were both excited at the thought of seeing new and different things, and, of course, helping the people and animals of the San Carlos Apache Tribe.

Even before the clinics began, we could see the amazing teamwork, efficiency, and leadership qualities of our group members. We were given an overview of diseases and conditions that we were likely to encounter, but the reality of how widespread these largely-preventable conditions are didn’t hit us until we began performing physical exams on client animals and saw the prevalence of these diseases in person. Our physical exams were slow at first since there are limited hands-on opportunities in the first year of veterinary school, but it did not take long for us to build up some confidence with the support of several RAVS veterinarians to rely on for guidance.

Anna, Marley and Laura
Anna Merrihew (left), Marley and Laura Miller (right).
Laura Miller

On our second clinic day, we were handed the file for a very happy, neutered male Chow mix named “Marley.” As we prepared to begin Marley’s wellness exam, the clients informed us that Marley had had blood around his penis for the last few days. After performing a thorough physical exam with no other abnormal findings, we examined his penis, which was actively dripping blood and was painful on palpation. On examination, we felt a somewhat firm, asymmetrical mass, about 1 inch in diameter, within the preputial sheath. The tumor bled significantly more when we were palpating it. We were suspicious that this might be a transmissible venereal tumor (TVT), one of the diseases reviewed in our orientation.

A TVT is a benign reticuloendothelial tumor of the canine family, usually seen in young, sexually mature intact animals of both sexes with access to uncontrolled sexual behavior, like free-roaming owned, stray or wild dogs. The tumor is passed from dog to dog when the friable TVT cells exfoliate from the tumor on one dog and transplant onto the mouth, nose or genitals of another dog during activities like mating or licking of the affected areas. The ability of the affected dog’s immune system plays a role in the course of the disease. Healthy dogs tend to experience a period of tumor growth and then spontaneous tumor regression. Immuno-compromised dogs experience tumor growth, multi-lobulation, ulceration, and contamination, and in less than five percent to 17 percent of cases, metastisis occurs. Once a dog has cleared a tumor, whether spontaneously or with the help of treatment, the dog’s immune system is able to protect them from future TVT transmission.

We called over the clinic’s lead veterinarian, Dr. Kate Kuzminski, so she could help us with our diagnosis. She attempted to pull back the prepuce, but was unable to do so due to the size of Marley’s tumor. With deeper palpation, Dr. Kuzminski was able to loosen and detach a piece of the friable tumor. The tissue was red, hemorrhagic and cauliflower-like in shape, as is typical of a TVT.

Since a definitive diagnosis of TVT can be made based on clinical exam findings and cytology, we performed an impression smear cytological examination of the mass. Under the microscope, we saw round to oval shaped cells with multiple, clear cytoplasmic vacoules, thus confirming our initial diagnosis of a TVT.

The next day, we were able to help with Marley’s treatment using an intravenous chemotherapy drug, vincristine sulfate. If Marley had not already been neutered at a previous RAVS clinic, we would have castrated him as well in order to eliminate his sexual activities. After the treatment, we monitored Marley over the course of the day.

Complete remission is seen in greater than 90 percent of cases when treated with vincristine once weekly for two to eight weeks. Unfortunately, this treatment regimen was simply not available for Marley on the San Carlos Reservation. The closest veterinary clinic to San Carlos is an hour away and Marley’s owners, like many of our clients, lacked the resources to pay for any veterinary services. With Dr. Kuzminksi’s help, we were able to make a plan for Marley to get treated again, once a month for the next two months, when RAVS would be returning to San Carlos for future clinics.

We saw hope for a positive change for many local animals [and our] involvement in Marley’s case reminded us why we chose to pursue veterinary medicine.

That evening, we presented our case to the rest of the team at our nightly rounds. We were so excited to be part of a real-life case diagnosis and have the ability to make a difference in Marley’s life. Being a part of the RAVS team helping the San Carlos Apache Tribe was an amazing learning experience. We saw hope for a positive change for many local animals. Our involvement in Marley’s case reminded us why we chose to pursue veterinary medicine in the first place. RAVS and our friend Marley have made a lasting impression on us.

For more information on Transmissible Venereal Tumors, read this review published in The Internet Journal of Veterinary Medicine.

Laura Miller and Anna Merrihew are students at the Michigan State University College of Veterinary Medicine, class of 2015.