For dogs, the realm of reality is stranger than fiction. Enter the transmissible venereal tumor (TVT), a peculiar growth that has been known since 1876. It's not an imaginary concept—it thrives where stray dogs intermingle and make contact. Remarkably, this tumor can be transmitted through physical touch. It doesn't discriminate by gender, affecting both male and female dogs. The mode of transmission is straightforward: it spreads when an existing tumor on one dog comes into contact with abrasions on a mucous membrane (genital, oral, nasal, etc.) of another dog. Mating is the most common avenue for transmission, but even routine interactions like sniffing can lead to its spread. While TVTs are usually found on the genitals, they can also affect other areas, such as noses, mouths, and anal regions.
Understanding the Transmissible Venereal Tumor
Often referred to as TVT, the transmissible venereal tumor can appear as a fleshy growth or manifest as genital bleeding. Initially, the tumor growth is localized, but over time, it may erode on the surface. The tumor is more prevalent in regions with a high population of roaming dogs or in shelters. While most TVTs are benign, they can cause discomfort and bleeding, lasting over nine months. Approximately 10% of cases see the tumor spread malignantly, especially in dogs with compromised immune systems due to age, poor health, or concurrent illnesses. Given its slow resolution and potential for spread, treatment is usually recommended over-relying on natural regression.
Curiously, the tumor cells aren't the host's own cells that turned cancerous. It's not a case of a virus transforming normal cells into cancer cells. Instead, the TVT is a tumor that grafts itself from one dog's body to another. These cells have a distinct chromosome count from the host's cells and don't originate from the host at all. Think of it as a few mosquito cells attempting to grow a new mosquito on your body after a mosquito bite.
Diagnosing and Treating TVT
Diagnosis involves either biopsy or cytology. Biopsy is more accurate, whereas cytology might only indicate the tumor as a "Round Cell Tumor" without further specificity.
Treatment Approaches
- Surgery: Surgery isn't as effective as anticipated. Recurrence occurred in 22% of cases within five months after tumor removal. Surgery is typically followed by other treatment methods.
- Vincristine: Vincristine, a chemotherapy agent, is delivered intravenously. Proper IV placement is crucial, as spillage can cause tissue damage. This method is usually successful after a few treatments, although a course of 3 to 6 weekly sessions is recommended for a cure. The addition of a canine non-steroidal anti-inflammatory medication (NSAID) may shorten the treatment course.
- Doxorubicin: Another chemotherapy agent, doxorubicin (Adriamycin), is also administered intravenously. It's more potent than vincristine and can be used if vincristine yields partial results.
- Radiation: External beam radiation is effective but costly and not widely available. For those with access to a suitable facility, radiation could be a viable option.
The transmissible venereal tumor might seem like a bizarre medical phenomenon, but it's a reality in the canine world. Despite its unusual transmission and characteristics, the tumor can be successfully managed with appropriate treatment. Veterinary professionals and pet owners working together can help ensure a positive outcome and relief from this curious infection.
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