Sarcoids are the most common skin tumours in horses. They are caused by abnormal growth of skin cells, strongly linked to the bovine papillomavirus (BPV). 

They’re not cancer, not contagious horse-to-horse, and not airborne - but they can be stubborn, recurring, and vary in severity. Six clinical types are recognised: occult, verrucose, nodular, fibroblastic, mixed, and malignant.

No - sarcoids are not cancerous, not contagious between horses, and not airborne. The current science suggests they’re linked to BPV (bovine papillomavirus), most likely spread by flies. 

A horse may carry the virus in its skin without obvious sarcoids, which explains why some seem to flare up after stress or injury while others never develop growths at all.

Because the virus often lies dormant in the skin, removing the visible growth doesn’t remove the underlying trigger. Studies have found BPV DNA even in “normal” skin on sarcoid-affected horses. Surgery or trauma to the area may even stimulate the virus, which is why recurrence is so common.

BPV-1 and BPV-2 are thought to be the main viral drivers behind sarcoids. Nearly all sarcoid tumours tested contain BPV DNA. The virus can exist silently in the skin and reawaken under the right conditions. Unlike in cattle, where papillomas often regress, in horses the virus tends to persist.

Yes, flies are a major suspect. The face-fly (Musca autumnalis) feeds on cowpats, then lands on horse eyes, mouths, or wounds, potentially carrying the virus with it. Female flies, in particular, seek extra protein from animal hosts. This is why sarcoids often appear around eyes and other delicate skin areas. 

Fly protection is an important part of management.

There is no single guaranteed remedy, but herbs can play a valuable role in supporting the immune system.

• Rosehip shells and barleygrass: featured in self-selection case studies, with reports of shrinking sarcoids over time.
• Lapacho bark: known for natural antiviral properties and often used in immune blends like BioCARE.
• Other supportive herbs: comfrey, barleygrass, phytonutrient-rich plants for resilience.

Topical remedies are widely used - from manuka honey and zinc chloride creams to toothpaste and even home recipes like flour + salt. Some owners report success, others none at all. 

Caution is needed: topical irritation can sometimes make sarcoids worse. Always monitor carefully and involve your vet before applying anything near sensitive areas like the eyes.