Pituitary macroadenomas and macroadenocarcinomas are being increasingly recognized in veterinary medicine. The term macroadenoma is poorly defined in veterinary medicine. Because pituitary imaging is not routinely performed in dogs with pituitary-dependent hyperadrenocorticism (PDH), the true incidence of pituitary macroadenomas is unknown but may range from 15% to 75% of dogs with PDH. Recent advances in endocrine testing and pituitary imaging have facilitated the detection of pituitary macrotumors, leaving routine imaging of affected patients as the last hurdle to early detection, treatment, and an improved quality of life.