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Background: The renin-angiotensin-aldosterone system (RAAS), when chronically activated, is harmful and RAAS-suppressive drugs are beneficial in the treatment of congestive heart failure (CHF). Mineralocorticoid receptor antagonists are widely used in the treatment of CHF in people.Hypothesis/Objectives: To determine if a mineralocorticoid receptor antagonist (spironolactone) is beneficial and safe in CHF due to myxomatous mitral valve disease (MMVD) of varying severity, we hypothesized that, when combined with furosemide, a combination product (S+BNZ) containing the ACE inhibitor (ACE-I), benazepril, and spironolactone, would be superior to benazepril alone. Animals: Five hundred and sixty-nine client-owned dogs, with MMVD and CHF (ACVIM Stage C) of ≤10-days' duration.Methods: After initial stabilization, dogs were randomized into a positive-controlled, double-blind, multicenter trial, to receive furosemide plus S+BNZ or furosemide plus benazepril. The primary outcome variable was the percentage of dogs reaching cardiac endpoint before Day 360. Cardiac endpoint was defined as cardiac death or euthanasia, recurrence of pulmonary edema, necessity for nonauthorized cardiac drug(s) or a furosemide dosage >8 mg/kg/d.Results: A significantly lower percentage of dogs treated with S+BNZ reached the primary outcome variable by Day 360 (OR = 0.56; 95% CI, 0.32-0.98; P = .04) and risk of dying or worsening from cardiac causes, was significantly reduced (HR = 0.73; 95% CI = 0.59-0.89, P = .002) vs benazepril alone. Adverse events, potentially associated with treatment, were rare and equal between groups.

Background: Torasemide is a potent loop diuretic with potential to treat congestive heart failure (CHF) in dogs. Objective: Evaluate the efficacy and safety of torasemide compared to furosemide in dogs with first occurrence of CHF caused by degenerative mitral valve disease (DMVD). Animals: Three hundred and nineteen dogs with new onset CHF attributable to DMVD. Methods: Double-blinded randomized noninferiority study of PO torasemide vs furosemide in addition to standard CHF treatment. The primary efficacy criterion was decreased pulmonary edema and cough and no worsening of dyspnea or exercise tolerance at day 14. Secondary endpoints included clinical response at day 84 and time to death, euthanasia, or premature study withdrawal for cardiac reasons. Results: Torasemide q24h (n = 161) was noninferior to furosemide q12h (n = 158); percentage of dogs meeting primary efficacy criterion at day 14 was similar between groups (torasemide, 74.4% [95% confidence interval (CI), 66.8%-81.0%] vs. furosemide, 73.5% [95% CI, 65.7%-80.4%]; risk ratio [RR], 1.01; 95% CI, 0.89-1.15; P = .87). Efficacy at day 84 showed similar results (RR, 1.05; 95% CI, 0.88-1.25; P = .6). Dogs receiving torasemide had a longer time to endpoint and were less than half as likely to experience death, euthanasia, or premature study withdrawal (hazard ratio, 0.36; 95% CI, 0.19-0.65; P = .001) than dogs receiving furosemide at any time during the study. Conclusion and Clinical importance: Torasemide was noninferior to furosemide as first line PO treatment for new onset CHF caused by DMVD. Torasemide significantly decreased risk of cardiac-related death or premature study withdrawal for cardiac reasons compared to furosemide.

This study suggests that spironolactone is well tolerated, and preliminary results support further investigation to evaluate the efficacy of spironolactone in the treatment of cats with cardiac failure due to cardiomyopathy.

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