The Stables

Sarcoids: The Skin Nasty

Just the mention of the word Sarcoids will tip any horse owner over the edge in fear of these scaly, nodule lumps that can appear on a horse. Having personally dealt with sarcoids with my horse, it can be a real roller coaster ride in deciding what route of treatment to take in dealing with these tricky lumps and what can be invariably skin cancer.


Skin problems in horses are very common and the majority of the times are harmless lumps and bumps. However certain skin problems or lesions need to be kept an eye on and for a vet to check that it is not the start of something more sinister growing, such as a sarcoid. Sarcoids are notable for their unpredictable behaviour and although small ones make look harmless, they can grow and spread very quickly.

They only affect the skin and they are most likely to be caused by a virus that is thought to enter the skin such as a fly bite or a wound. That’s why the majority of the cases found in the horses are where flies are attracted to being the eyes, neck, under the abdomen, upper limbs, tail and genitalia area. They tend to affect horses of any age but they are very common in young horses and then the older horse. Studies have shown that it can be a genetic cause with certain breeds that are more prone to suffering from sarcoids.

The sarcoid will start by being a dark grey flat or nodule wart-like lump. Some will stay the same size for many years and then suddenly change. Others can be fast growing from the start.


As soon as you see a lump on your horse’s skin that is grey in colour, you need to get a vet to check it. There is very rarely any of the horse’s hair on a sarcoid which can then be an indication that the lump is something more sinister. There are six forms of a sarcoid:

The Occult Sarcoid: this is a circular patch of hair loss with a grey, scaly surface. It can be mistaken being ringworm or tack rubs or lice infestation as similar in appearance.

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 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 (or biopsy!) of other forms of sarcoid elsewhere. They look horrific and can be “on stalks” or very invasive into the surrounding skin and deeper tissues. They can look like “proud flesh” initially, on a healing wound, so beware.

The Mixed Sarcoid: a cluster of suspicious-looking but vaguely-familiar nasties (as described above), of different ages, all jostling unattractively for position. Maybe occult, nodular and fibroblastic sarcoids all in there together.

The Malevolent Sarcoid: a sarcoid behaving like an aggressive tumour by spreading along lymph vessels forming other masses along these vessels and in local lymph nodes. These often develop following surgery on fibroblastic sarcoids (poor horse…poor owner….poor vet!!).


Treatment options are diverse in approach, suggesting that none is entirely satisfactory – whichever type of sarcoid you are dealing with. Failure and re-occurrence are common (and disappointing and often expensive). Selection of the correct treatment is essential and sometimes if the lesions are small and few in number they are best left alone, so long as they do not interfere with locomotion. I have listed below the common choices on vets advice when treating sarcoids. Have an open mind and decide what is best for you and your horse.

Surgical removal: fraught with potential for regrowth (even 15 years later!), with 90% of the re-grown lesions being nastier. Perhaps only a 15-20% success rate overall. Sarcoids in areas such as the eyelid and lower leg may be particularly difficult to remove surgically.

Cryosurgery: freezing, with perhaps only a 20-25% success rate. It works best on small, well-defined lesions but requires most of the mass to be removed surgically first and needs a long general anaesthetic, which horses object to!

Radiation therapy: this treatment uses such radiation sources as iridium 192 has proven highly successful, particularly in the treatment of sarcoids around the eye, with success rate of 98% reported from one study at Liverpool University. The treatment generally leaves very acceptable cosmetic results although it is expensive and success is limited by the size of the sarcoid.

Topical / Intra-lesional chemotherapy: vets have been attempting to treat sarcoids by slapping on highly toxic chemicals for over a hundred years. Liverpool University, under the guidance of Dr Derek Knottenbelt, has developed a topical treatment using a cytotoxic cream. It is available to veterinary surgeons in private practice but only on an individual case basis and under strict guidelines. It is applied usually every 72 hours for 3 or 4 occasions to individual sarcoids and causes rapid cell death. The sarcoid usually “falls off” at any stage between 2 days and several weeks after treatment is complete, but can cause considerable inflammation during the process and scarring afterwards. Horses can become quite sore during the inflammation phase too. These horses have often required courses of oral painkillers (usually “Bute”) and occasionally antibiotics if the inflamed lesions have become infected.

Homeopathic: There are less evasive ways of treating sarcoids with the use of homoeopathic treatments. You have to have an open mind and be solely responsible for treating a horse using alternative methods. There are however an increasing number of homoeopathic vets that you can consult to see if a natural method of treatment for sarcoids can be sort. Thuja tablets or cream and had a good success rate in treatment with the reduction of sarcoids where they can reduce in size and fall off. Do your research and seek professional advice before treating a horse or pony using homoeopathic remedies.

Whatever way you look at it, sarcoids are never good news…. Any sarcoid should be given a guarded prognosis because they often transform into a more aggressive form, they rarely resolve by themselves, and the treatment options available cannot always completely cure. I have seen horses for sale that have sarcoids and I have very mixed feelings about this. Realistically it is probably best to keep well away from buying a horse with sarcoid. However, some horses respond well to treatment and others do not. From experience the sarcoid will in time have to be dealt with and whatever treatment you decide it is always uncomfortable for the horse.

I hope I haven’t alarmed you with all this nasty information about this topic, but I feel very strongly for all horse owners to be aware of this horrible skin disease and I hope that you never have to deal with it!

by Samantha Hobden

DisclaimerThis article is an advisory post only. Although using homoeopathic treatments if used correctly are known for their safety, there are a few factors to consider.  It is solely your own responsibility when feeding natural supplements to animals. If you are giving any other type of drug or medication to your horse, please check with your vet to make sure it is still safe to continue with any homoeopathic treatment.