Sarcoids are a benign form a skin cancer found only on horses and donkeys. They may grow on any part of the body but are most often found in the groin area, and in the axilla. Occasionally they may be found to be present around the eyes and other parts of the face. It is thought that sarcoids are spread to susceptible animals by flies, from other horses with sarcoids.
There are five different types of sarcoid:-
Occult Sarcoid
This type often looks like a simple area of hair loss, with a patch of grey skin. They are usually about 1 - 2 cm. in diameter and require no treatment.
Verrucous Sarcoid
This type are wart like as in the illustration below.
This sarcoid has probably been treated in the past, note the white hairs. Verrucous means wart like, these growths are fairly benign, and opinions vary as to the need to remove them. Individual sarcoids or small number can be treated in most locations by cryosurgery. when they are found around the eye intralesional injections of B.C.G. are very effective. Unfortunately it is impossible to obtain B.C.G. in Britain at present.
Nodular Sarcoids
These sarcoids are round and smooth, and can often be squeezed out from the skin. They are fairly benign.
Fibroblastic sarcoids
These sarcoids often have ulcerated surfaces and attract flies. They can be removed by cryosurgery, but if numerous or large in size they can be treated with cytotoxic cream (W4 LUDE). This cream is made at Liverpool University and is generally applied only after special authorisation for its use has been obtained.
Fibroblastic sarcoids may grow relatively rapidly and may attain the size of a cricket ball. They may physically interfere with tack especially when they develop around the girth.
Malignant sarcomas
These are extremely rare, indeed they are hardly ever diagnosed. They are very aggressive tumours and send out cords of cells into the surrounding tissue.
Some sarcoids are a mixture of the five basic types and are simply referred to as 'mixed' sarcoids. As a rule sarcoids may spread on the skin surface, but do not invade into the rest of the body.
Many methods of treatment are available; the specific treatment used will depend on the location, size and number of the sarcoids. As with all cancer therapy no course of treatment is guarantined to be successful, and in most cases regular repeated treatments will be required until the problem resolves.
The most widely used form of therapy is cryosurgery. This involves freezing the sarcoid with a jet of liquid nitrogen. Smaller sarcoids will often respond to one round of freezing. Larger growths may require several treatments over a period of months. Cryosurgery has a number of advantages, it can often be performed under sedation rather than general anaethesia. It also avoids the need for conventional surgery that is often unsuccessful and can lead to problems of wound breakdown and delayed healing. As mentioned above some sarcoids can be treated by repeated applications of a special ointment, as with other treatments this is by no means universally successful.
If your horse is affected by sarcoids you should ask your vet to examine them, but remember that in some cases treatment is NOT necessary and can even be harmful. Monitor the sarcoids about once a month, watch out for sudden growth, or change from a benign type to a more severe form. Sarcoids are VERY common, and most affected horses suffer no ill effects at all.
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