Equine sarcoids are probably one of the most common and frustrating skin issues to deal with. The word ‘sarcoid’ stems from the word ‘sarcoma’ – a tumour originating from the connective tissue. The suffix ‘-oid’ refers to ‘like’, indicating that a sarcoid is a tumour ‘like a sarcoma’. The difference is that sarcomas are generally malignant, and sarcoids are usually not. Sarcoids are estimated to occur in one out of every 100 horses. They can appear on their own or on several locations of the horse, anywhere on the skin, and on horses of any age, breed or colour, although they tend to show up in horses who are middle-aged or older. Most common areas affected include the face (especially the mouth, eyelids and ears), legs, base of the tail, underside of the barrel, and potentially any area with scar tissue or a previous wound site.
The average equine sarcoid is found on the skin surface and resembles a wart. Some are small and flat, with a crusty surface or a normal skin covering. This type grows very slowly and might remain the same size for long periods of time, or might even spontaneously disappear. Verrucous sarcoids are often greyish in colour, and the skin can crack easily with flakes of scale being rubbed off from the surface. Interference with verrucous sarcoids (as with any sarcoids) can lead to rapid transformation into more serious and aggressive forms of sarcoids.
Nodular sarcoids are firm, round nodules that can appear anywhere on the horse’s body, but are often seen in the armpit, on the inside edge of the thigh and groin, as well as under the skin of the eyelids. They can be singular or multiple and vary in size. Interference with nodular sarcoids, accidentally or intentionally, can agitate them and result in rapid growth and possible change into more dramatic forms of sarcoids, such as the fibroblastic type.
Fibroblastic sarcoids are a more aggressive and invasive type of sarcoid. They are fleshy masses that grow quickly, bleed easily and often have ulcerated surfaces. They can often resemble ‘proud flesh’, and in fact can develop at the site of a wound. They can be found anywhere on the horse’s body, and can develop rapidly from other types of sarcoids such as verrucous and nodular forms.
The malevolent sarcoid is rare but the most aggressive of all the sarcoid types. Multiple growths can rapidly spread over a wide area of a horse’s body and grow in size just as quickly. The most common occurrence of the malevolent sarcoid is ulcerative nodular-like lesions grouped in large bundles. This condition can be so aggressive in nature that often there aren’t any treatment options.
How do I treat this?
Consult your veterinarian about your treatment options
The short answer is that unfortunately there isn’t a magical cure-all treatment for sarcoids. It is estimated there are over 40 different sarcoid treatments, between veterinary treatments and home remedies. It is clearly safe to say that there is no one single method that will be effective in each and every case. Horses with sarcoids should be assessed as early as possible for potential treatment. Sarcoids are unpredictable by nature, and no matter how similar two sarcoids look, a treatment that works for one might not work for another.
Although slow-growing sarcoids often cause minimal trouble to a horse, if they appear in an area where tack or equipment might rub against them (where the bridle or saddle may sit, or on the girth line), they can crack and bleed frequently and can cause significant discomfort, and may even attract flies when bleeding, leading to infection. As horse owners, we need to be considerate of our horses’ comfort if the sarcoids may interfere with riding – the horse’s welfare should always be a main priority.
Options for treatment, all of which have a moderate success rate, include the following:
Surgical removal of sarcoids is a possible treatment, but should be carefully considered and executed with caution, as failure to completely remove the sarcoid will predispose its recurrence, which can often be more aggressive. Surgical removal can be effective for small sarcoids in safe areas, but the failure rate is relatively high. The decision to remove a sarcoid surgically depends on many factors, including the type of sarcoid, its location, vital structures nearby, and how the sarcoid might affect the horse’s life. Nodular sarcoids often respond more positively to surgical removal.
Cryosurgery (freezing with liquid nitrogen)
Cryosurgery involves rapidly freezing and then slowly thawing tissues with liquid nitrogen in order to kill the rapidly dividing tumour cells while sparing the normal cells. It can be time-consuming and is only effective on small superficial lesions. It can also be used on sarcoid tissue remaining after a de-bulking surgery of very large sarcoids. There is a high recurrence rate with cryosurgery, so this is rarely a preferred treatment of choice.
Cisplatin is a chemotherapy drug that has shown good results when injected directly into sarcoids. The drug is mixed with sesame oil to give it slow-release properties, and is typically injected three to four times at two-week intervals. As cisplatin is a toxic drug, a vet should administer it, and care must be taken when injecting into the sarcoid. Cisplatin is dangerous to horses if used in any other method than injecting into the sarcoid, as cisplatin has been known to have side effects of vomiting, and horses cannot vomit. Local swelling and inflammation often occurs with sarcoids treated with cisplatin, often looking worse before they improve.
There are a vast amount of home remedies that have been used – far too many to explore here – but some include the use of mouthwash containing fluoride in the form of a spray, Epsom salts, turmeric, fenugreek and garlic. Home remedies such as these should be approached with extreme caution. They have no proven results of success or safety. It is absolutely paramount that the horse’s health and safety is kept the number one priority.
Frequently, veterinarians will opt to use a combination of treatments, depending on the size and location of the sarcoid and whether it is benign or rapidly growing. Sarcoid tumours tend to develop finger-like extensions into the normal tissue, so it can be nearly impossible to ensure that all the tumour cells have been removed, hence the attempt to use a combination of treatments to ensure a higher success rate.
Text: Hayley Kruger
Photography: Holistic Veterinary Medicine Centre, Pool House Vets, Shutterstock