Treatment of equine cutaneous neoplasia by radiotherapy using iridium 192 linear sources

The treatment of equine cutaneous tumours by conventional or cryosurgical techniques can be limited where the position of the tumour makes radical excision or freezing impractical or dangerous. Radiotherapy provides an effective and practical alternative. The use of iridium pins with guide needles allows accurate positioning of sources and uniform radiation fields to be achieved. The subsequent removal of the pins reduces the period of incapacity and reduces the radiation risk when compared to permanently implanted sources. Twenty-seven tumours on 26 horses were treated by this method with a 100 per cent success rate after a single irradiation. The technique of implantation is described and the criteria used to select cases and to assess the efficacy of this treatment are discussed.