12/02/2026
Lily, a beautiful 7-year-old mare, recently underwent laser surgical excision of multiple sarcoids at our practice.
Sarcoids are the most common skin tumours in horses. Although they do not usually spread to internal organs, they can be locally aggressive and invasive, often extending deeper into the surrounding tissues than they appear on the surface; they can enlarge, ulcerate and become painful or prone to infection. When located in sensitive areas such as around the eye, they can also compromise function and welfare, making prompt and effective management even more important.
Following Lilyโs surgery, her initial recovery was extremely encouraging. All her surgical sites appeared to be healing well, and the results in the first few weeks were very positive (Pic 1 and 2).
Unfortunately, despite this good start, the larger sarcoid on her left eye began to regrow after an initial improvement (Pic 3). This was understandably disappointing for both the owner and our team, especially considering how well the other surgical sites had healed. Laser sarcoid surgery has an approximately 90% success rate of no localised recurrence; sadly, this means approximately one in ten horses will have a recurrence of sarcoid growth as Lily had.
However, Lilyโs story did not end there. With the ownerโs vital support, we re-evaluated the case carefully and explored the different treatment options available. A treatment aimed at stimulating Lilyโs own immune system was selected; this involved injecting the tumour with a drug derived from a bacterial cell wall extract, designed to activate the bodyโs immune response and promote targeted killing of tumour cells.
This therapy can be expensive and requires multiple injections directly into the lesion, meaning careful planning, repeated visits, and close monitoring. As often happens with this type of immunotherapy, the tumour went through a phase of apparent growth before any improvement was seen(Pic 4). While this stage can be worrying, it is a recognised part of the treatment response in many cases (Pic 5). Over time, with a lot of patience and persistence, the sarcoid began to shrink and gradually disappeared! (Pics 7-8)
For more information on the treatment of sarcoids or if you have any questions please feel free to contact our teamโฆ
More information on equine surgeries can also be found via our website https://towcester-vets.co.uk/equine/services/surgery/
