Equine Sarcoids: Managing Chronic Skin Tumours in Horses

Sarcoids are the most common skin tumour in horses, caused by bovine papillomavirus, and can cause significant welfare harm through ulceration, irritation, and interference with tack and normal movement.

Key Facts

Equine sarcoids affect approximately 2-12% of horses and are the most frequently diagnosed equine tumour
They are caused by bovine papillomavirus types 1 and 2 (BPV-1 and BPV-2) and are not malignant but locally invasive
Six clinical forms exist: flat, verrucous, nodular, fibroblastic, mixed, and occult
Sarcoids rarely regress spontaneously and often enlarge progressively if untreated
Treatment options include topical chemotherapy (Liverpool cream), cryotherapy, laser surgery, and immunotherapy
Sarcoids in high-friction areas — girth region, eyelids, coronary band — cause particular welfare concern
Biopsy provocation can trigger aggressive growth — diagnosis should be clinical rather than histological where possible

Welfare Considerations

Sarcoid welfare impact depends heavily on location and type. Small occult sarcoids in non-contact areas may cause minimal welfare harm for years. Fibroblastic sarcoids in the girth region, around the eyes, or at the coronary band are a different matter — ulcerated, expanding masses in these locations cause constant pain through pressure, movement-induced irritation, or secondary infection. Periocular sarcoids can progress to occlude vision or prevent eyelid closure, causing corneal damage. Treatment decisions involve weighing the risks of provoking aggressive growth against the welfare cost of leaving untreated tumours in problematic locations. Early intervention with appropriate modalities by experienced practitioners gives the best welfare and cosmetic outcomes.

What You Can Do

Seek veterinary assessment for any new skin lesion on a horse — early identification improves treatment outcomes
Avoid biopsy of suspected sarcoids — clinical diagnosis is preferred to prevent provocation of aggressive growth
Treat periocular and girth-region sarcoids promptly given their welfare impact in these locations
Follow complete treatment courses — incomplete treatment risks aggressive recurrence
Consult equine oncology specialists for large, aggressive, or previously treated recurrent sarcoids