Effects of angiotensin-converting enzyme inhibition on plasma aldosterone concentration, plasma renin activity, and blood pressure in spontaneously hypertensive cats with chronic renal disease.

Hypertension is commonly associated with chronic renal disease in cats, and inappropriate activation of the renin-angiotensin-aldosterone system (RAAS) may contribute to the hypertensive state. Angiotensin-converting enzyme (ACE) inhibitors are commonly administered when hypertension is present to decrease plasma concentrations of angiotensin II and aldosterone, which cause vasoconstriction and sodium and water retention, respectively. The study reported here was conducted over a 6-month period to assess the effects of two commonly prescribed ACE inhibitors, enalapril and benazepril, on the activity of the RAAS and blood pressure in 16 spontaneously hypertensive cats with chronic renal disease. Plasma aldosterone and plasma renin activity were not significantly affected by ACE inhibitors in hypertensive cats, and systolic blood pressure did not decrease below 170 mm Hg with ACE inhibitor monotherapy in 14 of 16 cats. These results suggest that continued activation of the RAAS is present in hypertensive cats despite treatment with an ACE inhibitor, and ACE inhibitors should not be used as first-line antihypertensive treatment in hypertensive cats.