Sarcoids

 

Sarcoid is a common disease in all types of horses with 2-8% of horses being affected. Sarcoid is a form of skin cancer. Sarcoids can occur anywhere on the skin, although some parts of the body are more likely to develop sarcoids than others.

If a horse has had a sarcoid before they are likely to get more in the future. The more sarcoids a horse has at any one time the more it will develop so prompt treatment of each new lesion is recommended.

Some sarcoids can remain stable for long periods but also can suddenly enlarge without warning. Damage or trauma to a sarcoid can trigger more aggressive behaviour in the sarcoid and must be avoided. There are a small number of sarcoids that go away spontaeously (spontaneous resolution). This is very rare but has meant that many people think it is OK to leave a sarcoid which is never recommended given the risks that it could allow the lesion to get much worse and therefore much harder to treat.

All members of the equid family are affected worldwide; this includes horses and ponies, mules, donkeys, zebra, Przewalski horses and exotic asses. Donkeys are particularly prone to sarcoids.

Areas Commonly Affected by Sarcoids

 

Sarcoids can occur anywhere on the body, but there are some areas where the disease is more common:

• Where skin is thin.
• Where there is little or no hair.
• Where there is more sweating.
• Where flies attack and can feed without difficulty.
• At wound sites where the skin has been broken (the wound may not have been recent). This is an important factor in the development of sarcoids at abnormal locations such as the neck, upper body, and lower parts of the legs.

Sarcoid formation is a common cause for a wound failing to heal. If your horse has a wound that isn’t healing it should be tested for the presence of sarcoid.

Sarcoids never develop in internal organs and do not spread to these organs even if the skin lesions are extremely aggressive or extensive.

Sarcoids are rare on the upper trunk, back, and neck – unless there has been skin damage (injection sites, rubbing or injury).

Sarcoid is a form of Cancer

 

• Sarcoids have several features that mean they are a genuine cancerous (neoplastic) disease
• Sarcoids behave in a way that is just like a malignant or cancerous skin tumour
• Sarcoids are difficult to treat
• Sarcoids tend to recur. There are very few cases which spontaneously resolve
• Sarcoids spread across the body from site-to-site
• However some sarcoid lesions are small and have a benign clinical behaviour. They may remain stable for many months or even years
• Sarcoids are made of abnormally dividing fibroblasts. Fibroblasts normally provide support and structure to tissues
• The skin and the tissues directly below the skin seems to be the only place where this tumour can exist. It does not spread to the internal organs
• Sarcoids can infiltrate between muscles and can sometimes be very extensive and aggressive locally
• Sarcoids can be easily confirmed with a biopsy even with a very small sample. However biopsies are only required where there is not a typical appearance or where there has been poor wound healing