The equine sarcoid is a locally aggressive, fibrous skin cancer which can potentially result in death or the need to be euthanized. It is the most common dermatological neoplasm of the horse, found on an estimated 1 in 100 individuals.
Sarcoids can be located on any part of the body, but are generally found on the underside of the body, near the groin, and on or around the legs (especially the inside). Geldings have a higher predisposition to sarcoids than stallions or mares, and some breeds, such as the Quarter horse are also found to be more susceptible.
Sarcoids are unpredictable, both in appearance and behaviour. They may remain small and insignificant for the duration of the horses life, but may become aggressive and spread at a rapid rate. On the other hand, they may also disappear on a spontaneous basis.
Occult – These are flat, hairless, slightly crusty patches. They are often dark, and may be surrounded by dark hairless patches.
Verrucous (warty) – Raised, knobbly, quite spread, and sometimes ulcerated.
Nodular – Firm nodules that may have normal skin over them
Fibroblastic – Ulcerated, weeping, raised, sore lesions that may be cauliflower like.
Mixed – Exactly that! These can be a mixture of two or three different types above.
Malevolent – These are rare, malevolent types of sarcoids, that spread to lower tissues in the body.
A cow virus – the Bovine Papilloma virus – causes sarcoids. It is transmitted by flies.
A vet or experienced horse person may recognise a sarcoid just by looking at it, but a vet may take a biopsy to make a closer examination or confirm the diagnosis.
Traditional methods involve rubber rings to kill off the tissue, surgical excision to remove it, cryosurgery (freezing), injection with an immunomodulator (an active agent of immunotherapy), radiation therapy and injection of chemotherapy agents.
Sarcoid creams and ointments can also be found, these work to varying degrees. Contact your vet for more options.
If you suspect your horse has a sarcoid, get your vet to have a look at it!