The main characteristic findings in canine acromegaly are a visible increase in soft tissue mass, prominent skin folds, abdominal enlargement, and/or radiographic evidence of an increase in soft tissue mass in the orolingual, oropharyngeal, and orolaryngeal region. Acromegalic dogs almost invariably show some degree of respiratory stridor. Enlargement of the interdental spaces can be seen, but it is felt that these changes are less specific for the disease. Other possible findings include hyperglycemia, PU/PD, elevated SAP levels, and lowered PCV. For a conclusive diagnosis, the demonstration of elevated GH levels and, preferably, the demonstration of nonsuppressibility of these high GH levels is required. Basal plasma GH levels in acromegalic dogs varies considerably (for example, from 10 ng per ml to approximately 1500 ng per ml). GH-dependent circulating growth factor (that is, insulin-like growth factor I) is drastically elevated. Acromegaly is encountered in intact female dogs that were treated with progestagens to prevent estrus and in dogs during diestrus (progesterone phase). Progestagen withdrawal and/or ovariohysterectomy will result in a reduction of plasma GH and GH-dependent insulin-like growth factor concentrations and appreciable clinical improvement.