Sarcoids and melanomas are the two most common skin tumours we see in horses. They can occur from a young age and, frustratingly, if a horse develops one lesion, there are often others present or waiting to appear. While many of these tumours are classed as benign, they can still grow large, spread locally and cause significant problems depending on their size and location.

Early identification and appropriate treatment are key…..

Sarcoids

Sarcoids are extremely common and can affect horses and ponies of any breed or age. They are thought to be linked to a type of bovine (cow) papillomavirus. Not every horse exposed to this virus will develop sarcoids, but some individuals appear to be genetically more susceptible.

Types of Equine Sarcoids:

There are four main types of sarcoid, and it’s not uncommon for a horse to have more than one type at the same time:

• Occult – These are often subtle and may appear as small areas of hair loss or coat change. The skin can feel thickened or slightly grainy.
• Verrucose – Typically grey, scaly or warty in appearance. These are usually slow-growing and can easily be mistaken for ringworm or old scar tissue.
• Nodular – Firm, well-defined lumps under the skin that are usually hairless.
• Fibroblastic – Fleshy, ulcerated and often aggressive in appearance. These sarcoids can bleed easily and, because of their open nature, commonly attract flies.

Some sarcoids are a combination of more than one type, and multiple sarcoids can merge together to form a larger plaque.

Thankfully, malignant sarcoids are rare. These spread along lymphatic vessels, forming chains or networks of tumours, and require specialist management.

Because sarcoids can behave very differently from one horse to another, treatment needs to be carefully tailored. The earlier a sarcoid is identified, the more treatment options are available and the better the outcome is likely to be.

At Little Rock Equine Vets, once sarcoids are identified and photographed, we typically seek specialist input from Professor Derek Knottenbelt, an Equine Medicine Specialist with extensive experience in sarcoid management. He advises on and prescribes an appropriate treatment plan for each individual case.

Common areas where sarcoids appear:

• Around the eyes
• Between the front legs
• Midline of the abdomen
• Sheath region
• Inner thigh’s

These are usually areas where the hair is missing, often seen as the winter coat sheds in the spring.

Sarcoid Treatment in Horses:

Common sarcoid treatment options include:
✅ Topical chemotherapy
✅ Cryotherapy (freezing the tumor)
✅ Surgical or laser removal
✅ Immunotherapy to stimulate the horse’s immune system

Melanomas in Horses:

Melanomas are most commonly seen in grey horses and usually appear as black, hairless lumps. Common sites include under the tail, around the sheath or udder, and near the eyes, although they can develop elsewhere on the body.

Large swellings around the throatlatch area are often melanomas growing within the salivary glands or lymph nodes.

Melanomas can also develop internally and, in older grey horses, may occasionally be a cause of obstructive colic.

Unfortunately, melanomas are almost inevitable in grey horses. Many remain stable for years without causing any issues, but they do have the potential to grow, become malignant, or interfere with a horse’s comfort and welfare. When melanomas are at high risk of causing problems, early examination and a proactive treatment plan can make a significant difference.

Although melanomas can occur in non-grey horses, this is much less common. When they do occur, they tend to be more aggressive and should always be investigated promptly.

Melanoma Treatment for Horses

Over 80% of grey horses will develop melanomas during their lifetime. Early detection and removal, while tumors are still small, can prevent complications. Treatment may involve:
✔ Surgical removal
✔ Laser therapy
✔ Melanoma vaccines

Though melanomas can also occur in non-grey horses, they are much rarer but tend to be more aggressive.

When to Contact Us

If you notice any new lump, bump, skin change or wound that isn’t healing, it’s always best to have it checked sooner rather than later.

Our experienced team at Little Rock Equine Vets is always happy to advise.
📞 Call us on 01782 898102 to speak to one of our vets or arrange an examination.

Early assessment leads to better outcomes — and peace of mind for you and your horse.