Hypoadrenocorticism diagnosed by adrenocorticotropin stimulation test for aldosterone in a diabetic cat

A 6-year-old male neutered cat was referred with a 3-month history of lethargy, chronic constipation, intermittent vomiting, inappetence, progressive weight loss, dysphagia and polyuria. Previous treatment with intravenous fluids, antimicrobials, glucocorticoids, laxatives and appetite stimulants[megestrol-acetate (MgAc)] resulted in partial response. During the treatment course, the cat developed diabetes mellitus (DM). Physical examination revealed obtundation, cachexia, dehydration, pale mucosal membranes, generalised muscle atrophy, sialoadenomegaly and thoracolumbar pain as well as pain upon opening the mouth. Serum electrolyte analysis showed severe hypochloridaemia, hyperkalaemia and hyponatraemia, with a sodium to potassium (Na:K) ratio of 19.6. As the cat had been chronically treated with prednisolone at presentation cortisol concentration could not be reliably interpreted. Therefore, ACTH-stimulation was performed and pre- and post-ACTH aldosterone concentrations were measured, and were consistent with hypoadrenocorticism. Fludrocortisone treatment was initiated, and the clinical signs and electrolyte imbalances resolved; however DM persisted. Feline hypoadrenocorticism is rare, and unlike dogs, cats with this disease may present with dysphagia as a major clinical sign. Although MgAc may induce glucocorticoid deficiency and DM in cats, it has not been reported to induce mineralocorticoid deficiency with subsequent electrolyte imbalance, and its role in the pathogenesis of hypoadrenocorticism in this cat is questionable.