Sarcoids

Sarcoids have been the blight of horses, their owners and vets for generations. On an individual basis they can be a cause of considerable pain and suffering to horses, heartache to their owners and frustration (and embarrassment) to their vets!

What is a Sarcoid?

Known formerly as the equine “wart”, the sarcoid is a skin “lesion” occurring singly or in multiple numbers, usually on the head, groin or the axilla (armpits) of horses. The term “lesion” is used generally here, although the term “skin cancer” is perhaps helpful to emphasise the severity of the disease. They can appear over a variable period of time and in six distinct forms, such that in some cases they can be difficult to diagnose. There are many different types of skin disease in horses and as a general measure, the majority should be checked by your vet, since they can be confusing to identify.

What causes sarcoids?

Despite years of research and investigation, no one is absolutely sure what exactly causes Sarcoids. Some evidence suggests that biting flies may be involved in transmission of the disease. This may explain why patterns of the disease vary in different countries and why in some countries (but not here) the disease is regarded as contagious.

What do they look like?

As mentioned above, there are six distinct forms of the sarcoid, so distinct in appearance that it is often hard to justify the inclusion in the same “disease”.

The Occult Sarcoid: nothing to do with the “Exorcist”, this is a circular patch of hair loss with a grey, scaly surface. this is fairly serious and looks very similar to ringworm or tack rubs or lice infestation.

The Verrucous Sarcoid: looks a little like the above, grey and scaly, but extends deeper into the skin and is more irregular in outline. It can be mistaken for a variety of viral skin diseases and a tumour called squamous cell carcinoma, which is a real nasty!

The Nodular Sarcoid: these are mainly found under the skin, forming round nodules with apparently intact (but often thin and shiny) skin overlying. They are usually found around the eyelids and in the groin and look like a variety of skin tumours, including typical melanomas in greys.

The Fibroblastic Sarcoid: these are nasty and aggressive and look like true ulcerated skin tumours. They can often start after injuries to the skin, especially on the legs or after surgical removal of other forms of sarcoid elsewhere. They look horrific and can be very invasive into the surrounding skin and deeper tissues.

The Mixed Sarcoid: like the pudding trolley of a dubious restaurant, a platter of suspicious-looking but vaguely-familiar nasties (as described above), of different ages, all jostling unattractively for position. May be occult, nodular and fibroblastic sarcoids all in there together.

The Malevolent Sarcoid: a sarcoid behaving like an aggressive tumour by spreading along lymph vessels. These often develop following surgery on fibroblastic sarcoids.

As with most nasty skin troubles, your vet is likely best placed to decide on appropriate treatments. Sarcoids are never good news, and neither are many of the diseases they can get confused with. If your horse has skin disease, and you don’t know what it is (especially if you have tried treatment, eg. for lice, and it has failed) then get it checked by a vet. If you check vigilantly and react quickly, even if it's just a slight suspicion, you can usually find yourself in good stead to locate an appropriate treatment.