THE Royal Veterinary College (RVC) Equine Referral Hospital has become the first clinic in the UK to offer a new melanoma treatment for horses, specially targeted at lesions that are not able to be surgically removed. This will improve the way in which we are able to treat horses with melanoma, resulting in a better quality of life for those affected by the disease.

Melanoma is a very common nodular skin disease that affects older grey horses of any breed or gender. It is estimated that more than 80 per cent of grey horses will have at least one melanoma during their lifetime.

This new treatment specifically focuses on melanomas affecting the parotid region (salivary glands behind the jaw bones) and other anatomically sensitive areas that are less amenable to surgery. Until now, there has been no effective treatment option for lesions in these areas.

The treatment involves thermofield hyperthermia and intratumoral chemotherapy. Thermofield hyperthermia transfers a large volume of electromagnetic energy deep into biological tissue. The absorbed energy then causes molecular friction, gently heating the targeted area to therapeutic temperatures that selectively kills cancerous cells without harming the surrounding healthy tissue. In addition, the heat increases drug penetration into tumours and inhibits DNA repair in cancer cells. The equipment is safe, effective, and easy to use.

Horses receive three treatments, one week apart. This involves injection of the chemotherapeutic drug into the melanoma, under sedation, followed by hyperthermia using the thermofield unit. The entire procedure takes approximately one hour to complete and is relatively painless for the horse. A second hyperthermia treatment is then performed the following day, before the horse is discharged. The whole process is repeated for a total of three treatment rounds.

Dr Michael Heweston, Senior Lecturer in Equine Medicine at the RVC said: “Although thermofield hyperthermia combined with intratumoral chemotherapy is a relatively new treatment, I have been impressed with the response in the horses that we have treated thus far, and I am optimistic for the future. We will be collecting data over the coming months to report on its effectiveness.”