LUMPS AND BUMPS

Two kinds of skin lesion that commonly afflict horses and concern owners are melanomas and sarcoids.

Unlike melanomas in humans, the overwhelming majority of melanomas in horses are not malignant and probably reflect a storage anomaly rather that a cancer in grey horses. Many older, grey horses develop melanomas when their hair turns white and the melanin that normally pigments the hair is instead deposited in ‘lumps’ in the skin and other tissues. Melanomas may be found singularly or as multiples and are usually covered in normal skin although, occasionally they may ulcerate.

Melanomas are most commonly seen in the perineal region, under the tail, around the poll/throat and on the prepuce. The majority are slow growing without metastases. They are usually best left alone but may be surgically removed for cosmetic reasons or if they interfere with fitting of tack etc.

Sarcoids are locally aggressive fibroblastic tumours which are unique to the horse. Many horses have multiple lesions but they are not malignant and do not metastasise. Sarcoids may occur at the site of an injury that does not heal and are most frequently found on the head, legs and underside of the horse. The exact cause is unknown but there is some support for both viral involvement and genetic predisposition.
Sarcoids appear in three different forms: “warty”, “flat, black and hairless” or “proud flesh like” (the most troublesome).

Sarcoids may be difficult to treat and tend to re occur. Normally, combinations of two or more types of treatment are used. This may include surgery, cryosurgery (freezing), application of toxic ointment, formation of a “vaccine” (using frozen segments of sarcoid), stimulation of the immune system, “chemotherapy” (injection of medications into the lesion) and radioactive implants (expensive and hard to obtain).

If you are concerned about any lumps or bumps your horse may have, feel free to contact us at Riverdene to discuss this with the vets.