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Dogs are known for getting all types of lumps or bumps, with the most dreaded being a tumor. Tumors come in many shapes and sizes; some are benign, and others are malignant or cancerous. When you think of tumors, you believe they can't be transferable between dogs. However, Transmissible Venereal Tumor (TVT) tumors are spread from dog to dog.
Finding a tumor on your dog can be frightening, but knowing that there's a tumor that can spread from dog to dog can make you fearful for your dog's health. TVT can spread from dog to dog, typically through mating, but there are other ways dogs can contract this painful tumor.1 We’ll discuss this as well as the symptoms and treatments associated with TVT in dogs.
- What Is TVT?
- How Is TVT Spread?
- Signs & Symptoms Of TVT In Dogs
- What Causes TVT In Dogs?
- TVT Treatment Options
- Final Thoughts
What Is TVT?
Also known as Canine Transmissible Venereal Tumor (CTVT), or sticker tumor,1 Canine Transmissible Venereal Tumors (TVTs) don't look like other tumors you may find on a dog; they're shaped like cauliflower and are most often found around the genitalia. These tumors can be small or large, with the surface often becoming ulcerated and inflamed.2
TVT is most commonly found in temperate climates like the southern United States, Central and South America, parts of Africa, the Far East, the Middle East, and southeastern Europe. TVT is also a common tumor in areas where breeding is poorly controlled and free-roaming dogs are found in high concentrations.3 However, any dog can contract TVT, regardless of breed or geographic location.
How Is TVT Spread?
TVT is spread from dog to dog by direct contact with the tumor. Therefore, dogs can contract TVT through sexual activity, licking, sniffing, and biting the affected areas.4 Ultimately, the disease is spread by the transfer of the TVT cancer cells between dogs and causes tumors that are commonly located on the genitalia of males and females.1 However, these tumors can be found anywhere on the dog's body that came into contact with TVT, including the nose, lips, and mouth. For example, puppies can also contract TVT from infected mothers and develop a tumor in the mouth or lips.
Signs & Symptoms Of TVT In Dogs
The most common symptom of TVT in dogs is a red mass bulging from their genitals and bleeding or discharge around the area.5 Dogs with TVT will often lick around the area, spreading the tumor from the genitals to the mouth. Of course, since dogs can have TVT in other parts of their body, such as the nose and mouth, they may develop a cauliflower-like tumor that grows in size and oozes.
Even though the most common symptom is the visible tumor on a dog, TVT is painful, which could lead to other symptoms, such as lack of appetite, difficulty urinating if the tumor has caused a urethral obstruction, changes in behavior, depression, and increased vocalization.
What Causes TVT In Dogs?
TVT is caused by direct contact with the tumor. Skin-to-skin contact between dogs transplants cancer cells from one dog to another. For example, if one dog walks up to another and licks their TVT tumor, they can contract TVT in their mouth, while TVT affects the genitals through mating.
Science has dated TVT to being over 6,000 years old, and all TVT tumors carry the DNA from the first dog that contracted it – the founder dog. TVT is currently the oldest cancer known in nature.1
TVT Treatment Options
TVT is easily diagnosable and treatable. Diagnosis of TVT in dogs is fairly easy through an examination, especially of the dog's genitals. Your vet will take a sample of the tumor for biopsy like they would for any other possible cancer and fluid samples.5 Genital tumors in female dogs can be difficult to see, so vets may perform a digital vaginal examination or vaginoscopy.
TVT rarely spreads to other locations in the body. Still, your vet will confirm whether or not it's a malignant TVT cancer through visual diagnostics, which can help determine if it has metastasized and cancer is present. They may also perform lymph node biopsies to determine if cancer cells are present, and treatment can begin once a vet has made their diagnosis.
Spontaneous regression is not impossible, but TVTs are typically progressive and must be treated as soon as possible.4 Treatment methods include:
- Surgical excision: Surgical excision is not as common as other treatments since it's difficult to see the tumor on the base of the penis, in the vagina, or in the nasal cavity. However, surgery may be beneficial in instances where the tumor can be easily removed, depending on its location.
- Radiation therapy: Radiation therapy is used when chemotherapy isn't effective or can't be used on a dog with TVT. With this treatment, the tumor is targeted with high levels of radiation to kill or slow the growth of the cancer cells. Radiation can cure dogs with TVT, but it's not the best option for all dogs because it requires general anesthesia.
- Chemotherapy: Chemotherapy is typically done with a drug called vincristine in which a dog will receive weekly injections on an outpatient basis. Chemotherapy is the most popular choice of treatment because it's the most effective, with total regression expected by the sixth treatment.4 Unfortunately, while vincristine is highly effective, it does not always cure TVT in dogs, so a vet may prescribe a different drug in some cases.
While chemotherapy is the most effective treatment method, you'll want to discuss it with your vet because it comes with several side effects, like fever, nausea, and vomiting in dogs. In addition, dogs going through chemotherapy may experience a lack of appetite, so you'll need to know what to expect for each type of treatment.
If the tumor is benign, you can likely expect a complete cure.5 However, every dog is different, and treatment success will depend on their overall health. Left untreated, TVTs continue to grow, bleed and become more uncomfortable. Since TVTs are a form of cancer, they should be treated as soon as possible to improve a dog's outcome and the treatment's chances of success.
Many dogs are cured of TVT through treatment with an overall good prognosis unless the TVT tumor has metastasized and spread to other organs. Even though metastasis is uncommon, it can still occur without a genital tumor, so some dogs may have to undergo different forms of treatment.
TVT is a preventable type of cancer since it's only spread through direct contact with other dogs. Therefore, keeping your dog away from strays or dogs you don't know can help prevent painful TVT tumors. In addition, all dogs should be kept in fenced yards to prevent them from escaping to mate, especially intact males and females going through their heat cycles. Since spayed and neutered dogs are less likely to seek a mate, they're less likely to contract TVT. However, spaying and neutering don't directly prevent them from contracting the tumor.
Can dogs survive TVT?
TVT in dogs is highly treatable and curable through a few different forms of treatment. Chemotherapy is considered the most effective, so the prognosis for total remission is good. In addition, metastasis is unlikely, with only 5% of cases having cancer that spread to another organ.2
If not treated, TVT can be very painful for dogs and lead to death. TVT is cancer, and although it's most commonly found in tropical and subtropical climates with high populations of intact dogs, it can happen to any sexually active dog. Therefore, treatment is crucial to ensuring your dog's health after they contract TVT.
Of course, the best treatment is prevention. Since dogs contract TVT by coming in direct contact with the tumor on another dog, you should aim to keep your pet away from stray dogs or dogs you don't know. In addition, since the method of transmission is typically mating, you can prevent it by keeping your dog away from dogs most likely to try to mate with them.
For example, intact dogs are at an increased risk because they want to mate. While any dog, whether neutered or spayed, can get TVT, fixed animals have less interest in mating and are less likely to be in situations where a dog with TVT might try to mate with them.
Can TVT come back?
TVT can come back, and it likely will unless treated by radiation or chemotherapy. However, dogs that receive surgical excision are more likely to have recurring tumors because complete excision is difficult to achieve based on the location of the tumor in dogs.
Can TVT in dogs spread to humans?
TVT is not contagious to humans, so there's no transfer risk if you touch or come into contact with your dog's tumor. However, the tumor is transmissible between dogs, so if your dog is diagnosed with TVT, you must keep them away from other dogs until they're cured.
TVT is a highly transmissible tumor that is spread from dog to dog primarily through sexual contact. By limiting your dog's interaction with unknown or stray dogs, you can prevent TVT. Even though TVT is less common in spayed or neutered pets that are kept close to home, any dog can contract TVT from coming into contact with a dog that has it. Contact a vet immediately if you believe your dog has TVT or you notice a strange growth near or on their genitals.
Any time you notice a strange growth or tumor on your dog, no matter where it's located, they should be examined by a vet. While not all tumors are cancerous, some can be, and the earlier they receive treatment, the better the chances of success.
Worried about a growth you found on your dog? Talk to a Dutch vet to get help from home, today.
“Canine Transmissible Venereal Tumour (CTVT).” Transmissible Cancer Group, 27 Feb. 2015, https://www.tcg.vet.cam.ac.uk/about/ctvt.
Kutzler, Michelle. “Canine Transmissible Venereal Tumor - Reproductive System.” Merck Veterinary Manual, 18 Oct. 2022, https://www.merckvetmanual.com/reproductive-system/canine-transmissible-venereal-tumor/canine-transmissible-venereal-tumor.
“Canine Transmissible Venereal Tumor.” Canine Transmissible Venereal Tumor - an Overview | ScienceDirect Topics, https://www.sciencedirect.com/topics/veterinary-science-and-veterinary-medicine/canine-transmissible-venereal-tumor.
Kutzler, Michelle. “Canine Transmissible Venereal Tumor - Reproductive System.” MSD Veterinary Manual, 18 Oct. 2022, https://www.msdvetmanual.com/reproductive-system/canine-transmissible-venereal-tumor/canine-transmissible-venereal-tumor.
“Sexually Transmitted Tumors in Dogs.” PetMD, https://www.petmd.com/dog/conditions/cancer/c_dg_transmissible_venereal_tumor.