Transmissible Venereal Tumor in Dogs

Key takeaways

Transmissible venereal tumors (TVT) are an unusual form of tumor which can be transmitted through skin-to-skin contact between dogs.

  • The exact source of this cell line is unknown, but is thought be thousands of years old
  • The majority of tumors are found on or around the genitals but can also be found in the mouth, nose, anus, and other areas
  • These tumors do not often metastasize (spread within the body) and they tend to bleed, bruise, ulcerate, and have abnormal thickening of the surrounding tissues
  • Diagnostics include biopsy and cytology to determine the presence of TVT
  • Treatment is primarily chemotherapy with radiation and surgical removal if required
  • With chemotherapy and radiation, prognosis for full remission is good
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A closer look: Transmissible Venereal Tumor in Dogs

Transmissible venereal tumors are a highly unusual form of cancer in dogs. Cancer is a general term for uncontrolled cell growth which leads to the development of abnormal masses of tissue called tumors. Most forms of cancer arise spontaneously from within the body. Transmissible venereal tumors are contagious and spread between dogs through skin to skin contact, which is remarkably different from other forms of tumor development.

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Risk factors

Transmissible venereal tumors are seen more often in mixed-breed dogs, dogs that are still sexually intact, and stray or free-roaming dogs. TVT is more prevalent in tropical and subtropical climates, but is documented worldwide. It is often treatable and is not often metastatic leading to an overall positive prognosis.

If the tumors are not around the genitals, they may appear as cauliflower-like masses around the affected area, often the mouth, which may bleed or ulcerate.

Possible causes

The main cause of transmissible venereal tumors is through skin-to-skin contact. This is most often sexual contact but can involve sniffing, licking, or contact during birth.

Main symptoms

Masses are localized generally around the genitals. This can be one or more growths and is often accompanied by bleeding, bruising, or abnormal thickening of the surrounding skin. This may be accompanied by frequent licking of the affected area and general signs of physical discomfort.

Testing and diagnosis

After a physical examination and medical history, diagnosis of transmissible venereal tumors is confirmed through a biopsy or cytology.

Steps to Recovery

The primary method of treatment for this tumor is chemotherapy as surgery alone can lead to recurrence. Complete surgical excision and radiation therapy can also be used depending on the location and specific characteristics of the tumor. In very rare cases, the tumor can undergo spontaneous regression.

With treatment, prognosis is generally good with no incidence of recurrence. In cases where chemotherapy and radiation are not used, recurrence is more likely.

In cases of metastasis, prognosis is mixed and depends on the location of the secondary cancers and the spread within the body.


Transmissible venereal tumors are contagious to other dogs. They are transmitted through skin-to-skin contact activity and can be prevented by preventing physical contact with an infected dog. Spaying and neutering intact dogs reduces this risk by reducing mating activity.

Is Transmissible Venereal Tumor in Dogs common?

Transmissible venereal tumors are uncommon in dogs in North America, but are fairly common in other parts of the world.

Typical Treatment

  • Chemotherapy
  • Radiation
  • Surgery

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