Response of dogs with functional pituitary macroadenomas and macrocarcinomas to radiation

A prospective study was conducted to assess the use of radiation therapy for treatment of dogs with large, functional pituitary tumours and pituitary‐dependent hyperadrenocorticism. Four dogs received only pituitary irradiation, whereas two dogs received irradiation and concurrent mitotane treatment. Effects of radiation therapy on tumour size and function were assessed by sequential CT scans, ACTH assays and ACTH stimulation tests. Reduction in tumour size and resolution of neurological abnormalities occurred in all dogs. The mean and median survival time following irradiation for dogs in this report was 740 days and 743 days, respectively. Atnecropsy, a pituitary chromophobe adenoma was detected in three dogs, and a pituitary carcinoma in one dog; necropsy was not carried out on two dogs. Pituitary hypersecretion of ACTH persisted for at