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Equine Sarcoids

Sarcoids (or angleberries) are the most common tumours of horses and a viral cause is suspected. They are locally invasive tumours of the skin, which can remain small and dormant for many years before undergoing change and rapid growth. Most horses (>84%) will have many lesions as opposed to solitary sarcoid. Sarcoids do not metastasise. Sarcoids can occur in horses, donkeys and mule, and most commonly seen in animals between 1 and 4 years of age.

Some parts of the body are more susceptible than others. These include the eyelids, limb and the underside of the body and in male animals inside the sheath and on the penis. Site and position of sarcoids is very important for performance and as such lesions in the eyelid and girth region can be very irritating and cause problems with tack.

Sarcoids can develop along blood lines although there are no noted breed, age, sex or coat colour predispositions. Arabs have been showed to be more predisposed to sarcoids than other breeds.

There are 6 types of sarcoids:

  • Occult Sarcoids:
    Area of slightly thickened skin with a roughened surface, often hairless and very slow growing. Interference with these sarcoids can lead to a period of rapid growth.
  • Verrucous (warty) Sarcoids:
    Dry, horny and cauliflower-like, these arehairless and can have either a broad base or a stalk.
  • Fibroblastic Sarcoids:
    This type can look like proud flesh. It can be firm and nodular and its surface may be ulcerated.
  • Mixed Sarcoids:
    This is a mix between Fibroblastic and Warty sarcoids.
  • Nodular Sarcoids:
    This type is entirely under the skin and is found in areas where the skin is thin, such as the eyelids
  • Malignant Sarcoids
    These are extremely aggresive & abrasive 

There are 4 main ways of treating sarcoids. However it should be remembered that they can be troublesome to treat and can increase in size and number after any interference. Therefore during treatment care must be taken to look for new sarcoids developing. The choice of treatment depends on site and type of sarcoid.

  1. Surgery:
    Good selection of cases is required as success is low. Ligating pedunculated sarcoids with rubber bands is effective but they tend to recur. Laser excision is a better option however restricted by cost and practicality.
  2. Cryosurgery:
    Again case selection important as results can be poor.
  3. Immune-Mediated Therapy:
    Good results have been noted by a course of injections of BCG vaccine into lesions, particularly around the eye.
    Topical treatment using chemotherapeutic cream can be very effective though care must be taken to prevent local tissue reactions. This cream and other treatments can be injected into the sarcoid to improve results, if necessary. Immune boosting treatments including interferon are being used experimentally.
  4. Radiation
    Radioactive sources can be inserted into small tumours and high success rates are achieved, however cost and practically are limiting factors. This is currently only available at one site in the UK and there is a large waiting list for it.
  5. Do Nothing 
    Solitary or a small number of sarcoids that do not cause interference can be  left and they may resolve themselves.

Sarcoids can be small innocuous lesions however they should never be underestimated and treatment not undertaken lightly.


The material contained in this website is presented for information purposes only . The material is in no way intended to replace professional veterinary care or attention from a professional veterinary surgeon. 

The advice given in any of our web pages cannot be used as the basis for a diagnosis or choice of treatment.

Clyde Vet Group advises that you should always consult a veterinary surgeon about any queries with animals under your care.