Common Equine Skin Tumors

By Garrett Metcalf, DVM

It is rather common for horses to face having skin issues but what is causing this issue can be sometimes neoplastic growths or tumors that can be rather serious.  Skin is the most common region of a horse to experience neoplasia. There are many types of equine skin neoplastic diseases or tumors that occur with some being more concerning then others and they behave differently similar to neoplasia in other animals. This article will address the most common skin cancers, how to recognize them and touch on some treatments for each type.


Sarcoid growths are the most common skin tumor that occurs in horses. Sarcoids are limited only to the skin and do not spread to other tissues in the body like other cancers do. These masses are classified into different categories based on the behavior and appearance.  Lists of these are below.

  •  Occult sarcoids – These are flat, hairless mostly circular areas of dark patches that are often subtle.
  • Verrucose sarcoids – These are raised, wart like, dark areas that often spread into poorly defined margins. They can also be ulcerated on occasions.
  • Nodular sarcoids – These are firm and nodular skin lumps which may have normal skin over them but can be ulcerative.
  • Fibroblastic sarcoids – These are often ulcerated, weeping, raised sore lesions that may become pedunculated and cauliflower-like.
  • Mixed sarcoids – Sarcoids are commonly a mixture of two or more of the forms described above.
  • Malevolent sarcoids – These are rare, invasive sarcoids that spread over large areas of the body and grow rapidly.

There are many treatment options for sarcoids such as surgical excision, laser excision, injection of chemotherapeutic and immunostimulating drugs, electrochemotherapy, radiation, and topical therapies. For further information about sarcoids see a previous article in OKFR magazine exclusively on equine sarcoids.