Diseases and conditions image
Diseases and conditions image EquiMed

Also Known As

Skin eruptions, Skin lesions


Commonly found on the legs, abdomen, head, and around the eyes of a horse, sarcoids vary in size from less than an inch to several inches in diameter. While no definitive cause has been identified, DNA studies have linked equine sarcoids to Bovine Papilloma Virus, Types 1 and 2.

Six different types of sarcoids that affect horses are recognized in the medical community. They include:

  1. Occult: circular patches of hair loss with a gray, scaly surface that looks like ringworm
  2. Verrucose: gray, scaly, irregular in shape, and deeper than occult sarcoid
  3. Nodular: mainly under thin and shiny skin, varying in size; they commonly occur around the groin and eyelids
  4. Fibroblastic: aggressive, fleshy masses that resemble skin cancer and often originate as a complication of a skin wound; they grow rapidly and are extremely invasive
  5. Mixed: a combination of two or more types of sarcoid forming a colony
  6. Malevolent: the most aggressive type, commonly found in the elbow and face areas and spreads through the skin and along lymph vessels


  • Patches of hair loss with gray, scaly skin
  • Ringworm-like appearance
  • Wart-like appearance
  • Raised nodules
  • Fleshy masses similar to human skin cancer
  • Ulcerated areas
  • Multiple lesions


Although researchers have been trying to determine the cause of sarcoids for years, no definitive causes have been found. In some cases, a genetic basis for the sarcoids is possible.

The distribution of the lesions leads researchers to believe that flies and viruses are involved, but no definite link has been established. DNA studies suggest that equine sarcoids are sometimes caused by the cattle wart virus Bovine Papilloma Virus, Types 1 and 2.

Although sarcoids do not extend into internal organs, they do need to be treated. When they  are successfully treated, both the behavior and performance of horses noticeably improve, suggesting that chemical products from the sarcoids may cause internal consequences for the horse.


To date, no method of preventing the development of sarcoids has been proven effective. Good horse management, including fly control measures, may help. Some evidence suggests that thinner-skinned breeds, such as Arabian horses, have a greater tendency to develop the condition. Mares diagnosed with sarcoids should not be used for breeding purposes.


Many veterinarians are reluctant to deal with sarcoids, but treatment should begin as soon as a diagnosis is made because serious complications can develop.

Treatment must eliminate every abnormal cell or the sarcoid will return. Surgical removal is an option if the entire tumor along with a portion of surrounding tissue can be removed without serious consequences.

Freezing of the tumor has proven effective in some cases.

Shockwave therapy has also been successful, with radiation therapy seen as the treatment of choice for recurring sarcoids

Dig Deeper

This section contains articles specially selected by EquiMed staff for visitors wanting more information about this disease or condition. These articles are copyrighted by their respective owners and are available to you courtesy of EquiMed

About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.