Preliminary investigation of orally administered benazepril in horses with left-sided valvular regurgitation.

The research explores the impacts of the oral medication, benazepril, on horses enduring left-sided valve regurgitation by evaluating changes in echocardiographic and hormonal responses, concluding that the drug might reduce cardiac afterload.

Introduction

A notable shortage of information exists concerning the effects of orally administered angiotensin-converting enzyme (ACE) inhibitors on horses with valvular regurgitation. As such, the researchers’ aim was to investigate the echocardiographic and hormonal responses to oral benazepril administered to horses with left-sided valvular regurgitation.

Methodology

• The researchers undertook a prospective study involving random selection, a double-blind approach, and a placebo-controlled trial.
• The study recruited horses suffering from mitral valve (MR) and/or aortic valve regurgitation (AR). Those horses were then split into two groups: 6 received oral benazepril (1 mg/kg every 12 hours), while 5 received a placebo, both for 28 days.
• Echocardiography, a diagnostic method employing ultrasound to visualize the heart, was conducted both before drug administration to establish a baseline and after the 28-day treatment period.
• The team measured plasma renin activity, serum ACE activity, angiotensin II concentration, aldosterone concentration, and various biochemical variables at the onset and after 7 and 28 days of treatment.

Results

• Compared to the baseline, horses treated with benazepril showed a statistically significant decrease in left ventricular internal diameter during systole, aortic sinus diameter, and the percentage of the aortic annulus diameter occupied by the AR jet in comparison with those administered a placebo.
• Moreover, horses on benazepril had a greater increase in cardiac output and fractional shortening compared to the placebo group.
• Despite substantial serum ACE inhibition, there were no significant differences in renin activity and concentrations of angiotensin II and aldosterone either between the two groups or across the time points.

Conclusions

• The researchers concluded that, despite the study being limited due to the small sample size and short treatment period, benazepril treatment resulted in significant echocardiographic changes that could signify decreased cardiac afterload in horses with left-sided valvular regurgitation.
• However, they also indicated that further investigations using larger sample sizes are necessary to verify if the administration of benazepril proves helpful for horses with valvular regurgitation.