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.

A lot of scientific research has been devoted to investigating the sarcoid. This is because it is a disease that affects many horses and can impact on their welfare and performance.

Sarcoid above horse's eye

How Do Sarcoids Affect Horses?


  • Sarcoids may become ulcerated and infected
  • This can become a serious welfare issue and result in your horse becoming severely debilitated and metabolically exhausted
  • Some horses can develop systemic effects from sarcoids
  • This can include low blood proteins, and anaemia (low red cell counts). The effects may be so severe that the horse may have to be destroyed on humane grounds
  • Sarcoids can cause severe functional problems at certain body sites such as the eyelids, over the joints and at the coronary bands.
  • Treatment options for sarcoids at these sites are very limited and more likely to cause problems
  • Eyelid sarcoids can be very aggressive with extensive roots penetrating the muscles that control eyelid movement making treatment very challenging
  • Sarcoids can cause cosmetic problems
  • Sarcoids at certain locations can make it difficult or impossible to wear tack or rugs
  • Flies are attracted to sarcoids particularly in the summer months. This can be highly distressing for the horse
  • Sarcoids can affect the horse’s performance
  • Horses with sarcoids may perform better when the sarcoids are successfully treated and controlled
  • Sarcoids may limit the working life of horses
  • Sarcoids will lower the value of the horse and therefore the price you can achieve at sale
  • Sarcoids may render a horse unsellable
  • Even in high performance horses, sarcoid is a common cause of loss of commercial value
Flies above horse's eye

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 legSarcoid 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).

Flies above horse's eye

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

STOP AND THINK before you apply anything to a sarcoid.

Sarcoid is a form of cancer and should be treated with respect.

You wouldn’t treat your own skin cancer without seeking expert advice!

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Equine Medical Solutions Ltd
Office 1, STEP Building
Kildean Business & Enterprise Hub
146 Drip Road

Equien medical solutions sarcoid treatment

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