Venereal Tumors (Sexually Transmissible Tumors) in Dogs
- Occurrence: very rare
- Location of illness: Abdomen/pelvis
Venereal tumors in dogs, also known as Canine Transmissible Venereal Tumor (CTVT), are a rare type of cancer that is primarily transmitted through sexual contact between dogs.
The most important facts at a glance
Canine Transmissible Venereal Tumor (CTVT) is a unique, transmissible tumor in dogs that is mainly transmitted during mating, but also through sniffing or Licking tumor tissue from one dog to another. These tumors do not originate from the cells of the affected dog, but are transferred as “foreign” tissue from an infected dog to another. Scientific studies have shown that the CTVT cells are genetically descended from a dog that lived several thousand years ago. Symptoms include red masses on the penis or vagina, increased Licking in the genital region, and blood droplets. Diagnosis is made by clinical examination and cytological analysis. Treatment options are mainly chemotherapy with vincristine, sometimes combined with surgical removal or radiation therapy. The prognosis is generally good, especially with early diagnosis and treatment. For prevention, sexual contact between dogs should be controlled, for example by castration or sterilization, and dogs should be kept away from potentially infected animals. Regular veterinary examinations and awareness of the disease also contribute to reducing its spread.
Causes
Canine Transmissible Venereal Tumor (CTVT) is one of the few cancers considered transmissible. These tumors are unique because they do not originate from the cells of the affected dog, but rather through the direct transfer of tumor cells from an infected dog to another. This occurs mainly during mating, but can also occur through sniffing or Licking of tumor tissue.
CTVT belongs to a very small group of transmissible cancers that occur in animals, including the Tasmanian Devil, which suffers from a similar facial tumor. In dogs, these tumors represent a form of allotransplantation, where the tumor cells themselves act as “foreign” tissue that can bypass the immune system of the new host.
Scientific studies show that CTVT cells are genetically descended from a single original dog that lived several thousand years ago. This makes CTVT one of the oldest known continuous cell lines in the world. The ability of the tumor cells to bypass the immune system is enabled by genetic and molecular mechanisms that are still the subject of intensive research.
Symptoms
The symptoms of CTVT are often limited to the external reproductive organs but can also occur on other parts of the body if transmission occurs through contact with other mucous membranes. In male dogs, masses often appear on the prepuce, while in female dogs, the vulva may be affected. These tumors appear as cauliflower-like masses that often bleed or ulcerate.
In addition to the visible tumor masses, affected dogs may also show signs of discomfort, such as lethargy, loss of appetite, and, in severe cases, Weight loss. If the tumors metastasize to the oral cavity or nasal area, breathing problems or difficulty swallowing may occur.
Diagnosis
The diagnosis of CTVT is usually made through a combination of clinical examination and cytological analysis. The veterinarian will perform a biopsy or fine needle aspiration of the suspicious mass to collect cells for microscopic examination.
The cytological examination typically shows large, round tumor cells with a characteristic appearance. These cells have a high nucleus-to-cytoplasm ratio, multiple nucleoli, and a moderate amount of bluish cytoplasm. A definitive diagnosis is supported by these microscopic features.
Therapy
The treatment of CTVT is usually very effective, with chemotherapy being the preferred method. Vincristine is the most common chemotherapeutic agent, administered weekly over several weeks. This treatment leads to complete remission in most cases.
In some cases, surgical removal of the tumors may also be considered, especially if the tumors are small and easily accessible. However, surgical removal alone has a higher risk of recurrence, which is why it is often combined with chemotherapy.
Radiation therapy is another treatment option that can be used in cases where chemotherapy is contraindicated or tumors cannot be surgically removed. However, this method is less common and is usually offered in specialized veterinary oncology centers.
Prognosis and follow-up care
The prognosis for dogs with CTVT is generally very good, especially if the disease is detected and treated early. The majority of dogs respond well to chemotherapy and achieve complete remission. The recurrence rate is low if the therapy is performed correctly.
In cases where the tumors are not treated in time or if they metastasize, the prognosis may be worse. However, metastases are relatively rare in CTVT and usually occur in the regional lymph nodes or in the skin.
Prevention
The most effective method for preventing CTVT is to control the reproductive behavior of dogs. This can be achieved through castration or sterilization to minimize sexual contact, which is the main mode of transmission of the tumor cells.
In addition, dog owners should be careful to keep their animals away from unknown or stray dogs that may be infected. Regular veterinary examinations and awareness of the symptoms of CTVT can also help prevent the spread of the disease.
Another important aspect of prevention is educating dog owners about the risks and transmission routes of CTVT. An informed community can help reduce the spread of these tumors in the dog population.