Pituitary-dependent hyperadrenocorticism is more common in middle-aged to older cats (age range, 5 to 16 years; mean, 10 years) with female cats affected slightly more often. The most common presenting signs are insulin-resistant diabetes mellitus, cutaneous atrophy, polydipsia, polyuria, polyphagia, lethargy, abdominal enlargement, panting, obesity, muscle weakness, and recurrent upper respiratory and urinary tract infections. In some cases the first clinical sign noted may be skin fragility. Diagnosis can be challenging. Unlike in dogs, urine specific gravity is often concentrated despite polyuria/polydipsia, and serum alkaline phosphatase levels are not elevated. High serum alanine aminotransferase levels, hypercholesterolemia, hyperglycemia, and low blood urea nitrogen levels are common. The urinary cortisol/creatinine ratio is a simple and valuable screening tool in cats. The low-dose (0.1 mg/kg) dexamethasone suppression test is the test of choice. Cats do not respond well to mitotane but do appear to respond to trilostane (30-60 mg/cat/day). Therapy is monitored with weekly ACTH stimulation tests. Surgical treatment is an option, but postoperative management is challenging. Feline hyperaldosteronism, caused by a unilateral aldosterone-secreting adrenal tumor or bilateral hyperplasia, produces oversecretion of aldosterone, which causes hypokalemia, hypernatremia, and metabolic alkalosis.  The clinical signs result from associated systemic hypertension. The disease tends to occur in older cats (mean age 10 years). The most common clinical sign in 13 reported cases was hypokalemic polymyopathy presenting as ventriflexion of the neck. Other signs included paresis, hindlimb weakness, hypertension, fundic changes, blindness, polyuria/polydipsia, and polyphagia. Abdominal ultrasonography revealed an enlarged adrenal mass in 11 of 13 cats. Medical treatment of cats with primary hyperaldosteronism consisted of potassium supplementation and aldosterone-blockers such as spirolactone and amlodipine.

COMMENTARY: When feline hyperadrenocorticism was "first" reported, most cats had skin fragility syndrome. I have seen several cats in which this change reversed after treatment. Now that the disease is more commonly recognized, cats are being identified before this dramatic change occurs


Feline adrenal disorders. Chiaramonte D, Greco DS. CLIN TECH SMALL ANIM PRACT 22:26-31, 2007.