Acromegaly in a cat: Diagnosis by magnetic resonance imaging and treatment by cryohypophysectomy.

An eight-year-old, male neutered, domestic longhair cat weighing 6.5 kg was presented with a two-month history of polyphagia. The owners reported that the cat had always had a generous appetite but was now becoming destructive when seeking food. Three episodes of hyperglycemia (12.3 mmol/L-18. 1 mmolIL, reference values 3.5 mmol/L-9.0 mmol/L) and glucosuria (56-111 mmol/L), and on one occasion ketonuria (0.5 mmol/L), had occurred in association with consti-pation during the previous ten months, but had been resolved without insulin therapy. No abnormalities other than obesity were noted on physical examination. Results of a complete blood count, serum chemistry profile, and urinalysis were unremarkable. Hyperthyroidism and hyperadrenocorti-cism were considered to be possible causes of the cat's polyphagia. The serum thyroxine level was 10 nmol/L (reference values 9.3 nmol/L-57.9 nmol/L). An adreno-corticotropic hormone (ACTH) stimulation test (1) was performed. Serum cortisol levels assayed before, and at 30 and 60 minutes after, intramuscular (IM) administration of a total dose of 0.125 mg cosyntropin (Cortrosyn, Organon Canada, West Hill, Ontario) were 229 nmolIL, 270 nmol/L, and 276 nmol/L, respectively. These results were considered to be normal and no treatment was instituted. Six weeks later the cat was for evaluation of polyuria/polydipsia an polyphagia of two weeks' No noted on physical than mild