Functional morphology of spontaneous hyperplastic and neoplastic lesions in the canine pituitary gland

The pituitary glands of 10 male and 29 female dogs of different breeds had diffuse hyperplasia and hypertrophy of growth hormone or prolactin cells. Immunoreactive adrenocorticotrophin/melanotrophin was in the frequent focal hyperplastic lesions and micro- and macroadenomas of both pars distalis and pars intermedia of old female dogs. Pituitary tumours of other functional cell types were not found. Focal hyperplastic and neoplastic lesions usually were accompanied by spontaneous nodular hyperplasia or adenomas of the adrenal cortex as well as by changes in serum adrenocorticotrophic hormone and cortisol levels.