Background: Successful treatment of cats with hypersomatotropism by transsphenoidal hypophysectomy is described in small numbers of cats. Objectives: To describe the endocrine profile, survival, and remission rates of hypersomatotropism and diabetes mellitus in a cohort of cats with hypersomatotropism that underwent hypophysectomy between 2008 and 2020. Animals: Twenty-five client-owned cats with spontaneous hypersomatotropism. Methods: Retrospective study. Diagnosis of hypersomatotropism was based on clinical signs, plasma insulin-like growth factor-1 (IGF-1) concentration, and imaging of the pituitary gland. Growth hormone (GH) and IGF-1 concentrations were measured repeatedly after surgery. Survival times were calculated based on follow-up information from owners and referring veterinarians. Results: Median postoperative hospital stay was 7 days (range, 3-18 days). One cat died within 4 weeks of surgery. Median plasma GH concentration decreased significantly from 51.0 ng/mL (range, 5.0-101.0 ng/mL) before surgery to 3.8 ng/mL (range, 0.6-13.0 ng/mL) at 5 hours after surgery. Remission of hypersomatotropism, defined as normalization of plasma IGF-1 concentration, occurred in 23/24 cats (median, 34 ng/mL; range, 14-240 ng/mL) and 22/24 cats entered diabetic remission. Median survival time was 1347 days (95% confidence interval, 900-1794 days; range, 11-3180 days) and the overall 1-, 2-, and 3-year all-cause survival rates were 76%, 76%, and 52%, respectively. Conclusions and Clinical Importance: This study shows the beneficial outcome of hypophysectomy in cats with hypersomatotropism, marked by low death rate and a high percentage of diabetic remission and definitive cure.

BackgroundSpontaneous hypercortisolism or Cushing's syndrome in dogs is either pituitary or adrenal dependent, but concurrent pituitary and adrenal hypercortisolism also has been reported.ObjectiveTo determine how often concurrent pituitary and adrenal lesions are present in dogs with spontaneous hypercortisolism.AnimalsTwo hundred one client‐owned dogs with spontaneous hypercortisolism.MethodsRetrospective study. Pre‐ and post‐contrast computed tomography (CT) scans of the pituitary and adrenal glands were performed in dogs with confirmed hypercortisolism.ResultsIn dogs with dexamethasone‐suppressible hypercortisolism (122/201), 78 dogs (64%) had an enlarged pituitary gland (median pituitary height/brain area [P/B], 0.43 × 10−2 mm−1; range, 0.32‐1.21 × 10−2 mm−1). Two of these 78 dogs had concurrent adrenal lesions. In the remaining dogs (44/122; 36%), the pituitary gland was not enlarged. In the dexamethasone‐resistant group (79/201), the pituitary gland was enlarged in 47 dogs (59%; median P/B, 0.57 × 10−2; range, 0.32‐1.50 × 10−2 mm−1). Eight of these 47 dogs (17%) had concurrent adrenal lesions. In the remaining 32 dexamethasone‐resistant dogs (41%), the pituitary gland was not enlarged. Among them, 27 dogs had adrenal lesions and suppressed ACTH concentrations consistent with adrenal‐dependent hypercortisolism and 5 dogs were diagnosed with pituitary‐dependent hypercortisolism.Conclusions and Clinical ImportanceConcurrent pituitary and adrenal lesions were present in 5% of all dogs with hypercortisolism and in 10% of the dexamethasone‐resistant dogs. Diagnostic imaging of both pituitary and adrenal glands should be included in the diagnostic evaluation of every dog with spontaneous hypercortisolism to obtain information needed for estimation of prognosis and choosing the optimal treatment.