04/16/2025
Los Angeles Public Health Warning
4.16.25
Animal Health Advisory: Transmissible Venereal Tumor (TVT) in imported dogs in Los Angeles County
Key Points:
Transmissible venereal tumor (TVT) was recently reported in eight dogs in Los Angeles (LA) County. The cases were diagnosed between 2021 and 2025. TVT is not usually found in dogs in LA County.
All cases were likely infected in areas outside of the LA County. Six dogs were originally from Mexico, one was from an unstated location in South America, and one was a stray dog from San Diego County.
Transmissible Venereal Tumor (TVT) is a contagious cancer that can spread between dogs. It is spread between dogs by sexual contact (mating), and through direct contact with the tumor and abraded skin or mucosal tissue. It is highly treatable, and cures are often obtained.
Veterinarians should obtain a detailed travel history for all dogs and consider TVT when examining dogs imported or rescued from places where TVT is commonly found, including Mexico, Central and South America, East Asia, the Middle East, and parts of Africa. Note TVT may be also circulating among stray dogs in southern areas of Southern California.
Veterinarians in LA County should report cases of TVT to LA County Veterinary Public Health.
Dear Veterinary Colleagues:
The Veterinary Public Health (VPH) Program recently received reports of Transmissible Venereal Tumor (TVT) in eight dogs in Los Angeles County. Two of the cases reside in Long Beach and were therefore reported to the Long Beach Department of Health and Human Services.
The eight TVT cases occurred between 2021 and 2025. All the cases likely became infected before moving to LA County. Specifically, six dogs originated from Mexico, one was from an unstated location in South America, and one was a stray dog from San Diego County. So far TVT does not appear to be spreading in LA County dogs.
The breeds of dogs were highly variable, including a Golden Retriever, Pug, German Shepherd, Shiba Inu, and four mixed-breed dogs of varying sizes. Seven of the cases had urogenital tumors (5 male, 2 female). One dog had a facial tumor that invaded the bone (initially thought to be an abscess). Five dogs were treated and cured, and one is still undergoing treatment. Treatment and outcome information was not available for 2 dogs.
What is Transmissible Venereal Tumor (TVT)?
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 and is very rare in most of North America. 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), and through direct contact with the tumor and abraded skin or mucosal tissue.
Clinical Signs of TVT
TVT tumors in urogenital areas of dogs may not be noticed initially. They are usually red and fleshy and are found around the base of the p***s in male dogs, or in the va**na of female dogs. For male dogs, the prepuce may conceal the tumor.
TVT tumors can be found elsewhere on the body such as in the skin, on the head 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. Dogs may have a single TVT tumor or multiple tumors.
Affected dogs may have blood in the urine, blood dripping from the pe**le sheath or va**na, or show discomfort in urination. Dogs with TVT may excessively lick areas affected by the tumors.
Diagnosis
Diagnosis is made via cytology or biopsy of the tumors, combined with consideration of the travel history of the animal and the anatomic location of the tumor(s). TVT cells look similar to certain other kinds of cancer cells, so a laboratory may recommend performing certain stains to help rule out other kinds of cancer. Most cases of TVT respond very well to treatment and are curable, further supporting the diagnosis.
Treatment
TVT is treated with chemotherapy. It is often possible to completely cure TVT, even when the tumors appear large. The most common treatment consists of weekly intravenous injections of a single 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. Veterinarians are encouraged to either consult with, or refer to, an oncologist for further information about treating dogs with TVT. A repeat biopsy of the area may be needed after treatment is completed, to confirm that it is resolved.
Preventing spread of TVT
Learning how to recognize TVT is one of the first steps in preventing local spread of the disease. Always take a thorough travel / origin history for any new patient. Encourage dog owners to ask the rescue group or dog breeder from whom they obtained the dog to clarify which country (and which part of that country) the new dog came from, and if they have ever seen TVT in their dogs. Perform a thorough physical exam. If a dog has TVT, it is crucial to keep them away from other dogs until they have been treated and cured. Affected dogs should always be spayed or neutered.
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