The cause is not fully understood but a viral cause is suspected. We do know that once a horse has developed one sarcoid that horse is predisposed to developing more sarcoids.

Contagious means that they can spread from one animal to another. This does not seem to be the case.

They typically occur in areas from the tail beneath the back legs, along the midline of the belly , between the front legs and around the head. These areas may be most affected because they are the most hairless. They occur as several different forms described below.

Occult Sarcoids. These are flat, hairless, lichen-like, slightly dry and crusting, dark patches. They often have a smooth, dark hairless area around them. They are most common on the inside of the upper hind legs, the neck and around the eyes.

Verrucose Sarcoids. These are raised, knobbly, 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.

Fibroblastic Sarcoids. These are often ulcerated, weeping, raised sore lesions that may develop a stalk and become 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 invade deeper tissues beneath the skin.

A small sarcoid in an area which has plenty of loose skin and does not rub on tack is easier to treat and less problematic than a sarcoid in more sensitive areas. Particular problems are sarcoids around the eyes, on the ears, at the corners of the lips where a bit rubs and on the girth line. These need aggressive treatment whilst still small. It is especially important to treat sarcoids around eyes before they enlarge.

A definitive diagnosis can only be made by looking at a biopsy, or tissue sample, under the microscope. This needs to be sent off to a laboratory. However taking a biopsy without removing the entire sarcoid can make it more aggressive so in most cases we start treatment based on the location and character of the lesions.

No one treatment is suitable for all sarcoids and it is essential that individual cases are assessed by a vet to ensure that the best treatment is selected. Sarcoids can be difficult to treat and unfortunately this has encouraged many bogus treatments to be marketed. If you would like us to discuss your horse's sarcoids while we are visiting for another reason please feel free to ask.

Treatments may include;

Banding with rubber rings. Banding is a very satisfactory treatment where the sarcoid has a distinct neck or stalk. It is cheap and has a high success rate. Unfortunately it is not suitable for sarcoids which have no "neck".

Chemotherapy drugs, applied as a cream onto the sarcoid. This is a very effective treatment for many sarcoids. We use cream supplied by the University of Liverpool and need to take photos of the sarcoids in order to apply for a supply of cream. Although it has a good success rate, it is a relatively expensive treatment and requires at least 3 visits. It is not suitable for all sarcoids, particularly those where the cream will be easily rubbed onto other sensitive tissues.

Chemotherapy drugs, injected into the sarcoid. This is a treatment which we occasionally use for the most stubborn sarcoids.

Surgical excision is a treatment which has had some bad press in the past. This is beacuse it may have been used inappropriately on large, poorly defined sarcoids. In such cases it is difficult to excise the entire sarcoid and regrowth often occurs more aggressively. Excision of smaller, well localised lesions is a useful treatment. With all surgical excision it is important to take a wide margin around the sarcoid. Sometimes we take the majority of a sarcoid off surgically but treat the remnant with cream or freezing. This is known as debulking.

Freezing (cryosurgery). We use liquid nitrogen on some sarcoids. It has a good success rate for treating flat sarcoids.

Injection with BCG vaccine in order to trigger the horse’s immune system to reject the sarcoid.

Implantation of radioactive wires. This has to be done at a university hospital with expertise in the procedure.

It is occasionally possible to successfully remove all of a horse's sarcoids but in many cases the treatment results in control rather than resolution of the lesions.

We particularly recommend a website written by Derek Knottenbelt from the University of Liverpool. This can be found by clicking here.

 

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