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Sarcoids are the most common skin tumour in equids. They are locally aggressive, with a high propensity for recurrence. Since they are a form of cancer, they need to be treated with due respect.

Luckily they are non-metastatic (i.e, they don’t spread to internal organs), however they can have deep roots and be much bigger than the surface lesion leads to believe.

Sarcoids are thought to be caused by Bovine Papillomavirus, the same virus that causes warts in cattle. In some horses these warts just go away with time, but in others become sarcoids.

There is no breed, age or sex predisposition for sarcoids, however some individual horses are prone to developing multiple lesions.

The areas that are most prone to sarcoids are those with thin skin like legs, head and trunk, but sarcoids can also develop over wounds.

Fly control is paramount to help with sarcoid control and avoid spread between horses.

Sarcoids are an issue at pre-purchase exams,but they can also become a welfare concern as they grow.

Sarcoids can stay small and quiet, but some grow and become trouble.

The location of the sarcoid dictates prognosis and treatment: they might interfere with bridle, girth or saddle. If they are located close to the eyes they are generally bad news.

Large sarcoids can ulcerate, especially if there is any rubbing on them. This is painful, causes blood loss, protein loss and infection. Large sarcoid masses can affect horse’s performance too.

Diagnosis and treatment can be formulated often based on clinical exam however skin biopsies are often paramount in establishing the correct treatment.

The horses’ skin can be affected by different types of cancer: squamous cell carcinoma (mainly around eyes), basal cell carcinomas, lymphoma, melanoma (in grey horses), mast cell tumour, to name a few.

There are 6 types of Sarcoids:

  • Occult - Hair loss, skin thickening, scaling.

  • Verrucose - Warty looking, can be quite big.

  • Nodular - Can be freely moveable or have a deep root.

  • Fibroblastic - Fleshy apperance, can have a broad base, or be pedunculated (on a stalk)

  • Malignant - Extends widely into skin and underlying tissues, locally invasive, and very hard to resolve.

  • Mixed - These can have unusual appearances, and may require biopsy to categorise.

The importance of appropriate treatment choice:

Appropriate treatment avoids reoccurrence. Our advise is please do not ignore them as it gets a lot more expensive to treat larger sarcoids.

Different treatments include:

Laser resection: this is rapid and effective but not all sarcoids can be removed surgically.

Topical Creams: these work exceptionally well in tracking the sarcoid deep into the tissue and killing it off. They are cancer drugs therefore need to be handled with care. These are supplied by Prof. Knottenbelt.

Ligation - by far the cheapest option, can be effective but only if no deep root is palpable.

"Smart" sugery - "one cut, one blade" to avoid spreading of cancer cells.

Credit for some of the pics above: Prof D Knottenbelt,

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