Veterinary Public Health Program
313 N Figueroa St. Rm 1127
Los
Angeles, CA 90012
Tel (213) 288-7060
Fax (213) 481-2375
vet@ph.lacounty.gov
Key Points:
- Transmissible Venereal Tumor (TVT) is a contagious cancer that can spread between dogs. It is most commonly spread between dogs by sexual contact (mating), but can spread by the bite from an infected dog if some of the tumor cells were in the dog's mouth.
- As of April 10, 2025, eight cases of TVT have been reported in dogs in LA County, occurring between 2021 and 2025. Six dogs originated from Mexico, one originated from an unstated location in South America, and one was originally a stray dog from San Diego County.
- Veterinarians should obtain a detailed travel history for all dogs and be aware that TVT may now be circulating in Southern California.
- Veterinarians and dog owners should consider TVT as a possibility in dogs imported from places where TVT is commonly found, including: Mexico, Central and South America, East Asia, the Middle East, parts of Africa, and perhaps the southernmost areas of California.
- Veterinarians in LA County should report cases of TVT to LA County Veterinary Public Health.
What is Transmissible Venereal Tumor in Dogs (TVT)?
Transmissible Venereal Tumor (TVT) is a contagious cancer that can spread between dogs. It is most common in parts of the world with high numbers of free-roaming unspayed / unneutered dogs. TVT does not spread between any other type of animals and does not infect people.
TVT is most commonly spread between dogs by sexual contact (mating), although it can sometimes be spread by the bite from an infected dog if some of the tumor cells were in the dog's mouth. TVT tumors are usually red and fleshy, and are found around the base of the penis in male dogs, or in the vagina of female dogs. TVT tumors can be found elsewhere on the body of a dog, such as in the skin, on the head or around the eyes.
TVT does not appear to be spreading in Los Angeles County dogs, however cases have been diagnosed in dogs imported from other countries, and in one dog that had been a stray in San Diego County.
TVT Symptoms in Dogs
Symptoms of TVT vary depending on where on the dog's body the tumors are located, and may include:
- Blood in the urine, or bleeding from the vagina.
- Excessive licking of the genital areas. Potential discomfort in urination.
- Red, fleshy tumor or tumors on the base of the penis in male dogs (often hidden inside the sheath), or inside the vagina in female dogs.
- Tumors in the skin, in the mouth, or around the eyes. TVT tumors in the skin may be covered with hair or open, ulcerated and red. Sometimes they can have a cauliflower-like appearance. They may also become infected with bacteria.
TVT reported in dogs in Los Angeles County (as of April 10, 2025)
Total Cases: 8 dogs (6 male, 2 female) diagnosed between 2021 and 2025. (Note that two of the cases were located in Long Beach and were also reported to the Long Beach Department of Health and Human Services). Two cases were diagnosed in 2024, and one so far in 2025.
Clinical signs: 7 dogs with tumors on genital areas (5 male, 2 female), 1 dog with tumor on the face (initially thought to be an abscess)
Outcome: 5 dogs were treated and cured. 1 is undergoing treatment. Treatment and outcome information was not available for 2 dogs.
Travel: Most dogs were obtained from dog rescue groups. Six dogs were from Mexico, one was from South America, and one was a stray dog from San Diego County.
Reporting TVT
Veterinarians practicing in Los Angeles County should report cases of TVT.
Send a completed Animal Disease or Death Reporting Form along with the medical records and laboratory results to vet@ph.lacounty.gov or fax to 213-481-2375.
Diagnosis, Treatment & Prevention
Diagnosis
TVT is diagnosed by a veterinarian via taking samples (biopsy or cytology) of the tumor or tumors and submitting them to a laboratory for analysis.
Treatment
TVT is treated with chemotherapy. It is often possible to completely cure TVT, even when the tumors appear large. A common treatment consists of weekly intravenous injections of a chemotherapy agent called vincristine, always given by a veterinarian. Typically 3-8 injections of vincristine are needed to obtain a cure, although more may be needed. Other chemotherapy drugs may sometimes be used instead. A veterinarian may need to repeat a biopsy of the area afterward to be sure TVT is gone.
Prevention
Knowing how to recognize and prevent the spread of TVT is most important when adopting or buying a dog from another country where TVT is common. Ask the rescue group or dog breeder to clarify which country (and which part of that country) your new dog came from, and if they have ever seen TVT in their dogs. Share this information with your veterinarian so they can examine your dog for diseases that are not usually found locally, including TVT. If your dog has TVT, make sure it is spayed or neutered, and keep it away from other dogs until it has been treated and cured.
Frequently Asked Questions
No. TVT only spreads between dogs. It does not spread to people or to other animals.
Unfortunately, yes. They can spread it by mating with other dogs, or possibly by licking their own tumors and then biting or possibly licking other dogs. Spay or neuter any TVT-infected dog, and keep it away from other dogs until it is cured. If you are taking your dog to a new veterinarian, make sure they know that your dog has TVT so they can take steps to prevent spread.
Yes! Most cases of TVT can be cured by a veterinarian. See the Treatment section.
Resources & News
Resources
Merck Veterinary Manual
Case Reports for Veterinarians
Journal of the American Veterinary Medical Association
