Radiotherapy for the treatment of periocular tumours in the horse

Periocular tumours are a relatively common problem in the horse, and present some unique challenges. Radiotherapy has long been considered the ‘gold standard’ for the treatment of periocular tumours in the horse, and there are various techniques of delivering this treatment. Although teletherapy and plesiotherapy are occasionally used, the most commonly used technique is interstitial brachytherapy. Low-dose rate interstitial brachytherapy has reported success rates of between 74 and 100% for the treatment of periocular sarcoids, and other tumours can also be successfully treated using this technique. There are significant disadvantages to the low-dose rate brachytherapy approach, and recently, a technique using high-dose rate brachytherapy has been described with a reported success rate of 100% for periocular sarcoid treatment. Electronic brachytherapy is a technique which may provide an alternative to high-dose rate brachytherapy, but its use for the treatment of periocular tumours has not been reported, and the requirement for general anaesthesia is a significant disadvantage.