Treatment of periocular tumours of horses using radioactive gold198 grains

The literature is briefly reviewed concerning the clinical features of equine cutaneous tumours. The data from 19 horses with periocular skin tumours are reported together with the results of their treatment by implantation with radioactive gold198. The principles governing the implantation of radioactive sources are explained and a method for computing the initial activity of the sources is outlined. Five histologically different tumour types were treated in this series of 19 horses, 2 horses were bilaterally affected. The techniques of implantation using a simple needle/stillette combination and a purpose built gold grain implantation gun are described and the postoperative course of the animals is traced. The treatment was successful in ablating the tumour mass and preventing regrowth in 19 of 21 periocular tumour groups. The cosmetic effects of the treatment were found to be satisfactory. Emphasis is laid on the care needed in handling the radioactive material and on the need for a thorough understanding of the principles involved in radiotherapy. Doses received by the operator during an implantation procedure are quoted which show that the technique is safe as well as being effective.