Medetomidine-vatinoxan (Zenalpha) results in reduction of systolic function, blood pressure, and heart rate with prolongation of electrocardiographic intervals in healthy dogs.

MVZ sedation significantly impairs cardiac function and hemodynamics, warranting caution in dogs with or screened for cardiovascular disease.

This prospective pretest/posttest study evaluated the cardiovascular effects of medetomidine-vatinoxan (Zenalpha; MVZ) in 21 healthy client-owned dogs using echocardiography, blood pressure measurement, and 1-hour Holter monitoring at baseline and following sedation per manufacturer guidelines. MVZ produced statistically significant reductions in multiple echocardiographic systolic function parameters, including ejection fraction, fractional shortening, end-systolic volume index, stroke volume index, and fractional area change. Blood pressure and heart rate were also significantly reduced. Electrocardiographically, PR and absolute QT intervals were prolonged, while corrected QT interval and arrhythmic burden scores showed nonsignificant increases. Notably, 62% of dogs (13/21) developed or experienced worsening atrioventricular nodal conduction abnormalities on Holter monitoring, and 9.5% (2/21) developed or had worsening atrial or ventricular ectopic activity. A clinically relevant finding was that 71.4% of dogs (15/21) had two or more echocardiographic systolic function parameters fall below established reference ranges during sedation. These findings indicate that MVZ produces meaningful hemodynamic depression and electrophysiologic alterations even in healthy dogs. Clinicians should carefully weigh these cardiovascular effects when considering MVZ sedation in patients with known or suspected cardiac disease, or in dogs undergoing cardiac screening examinations, as sedation-induced changes may confound interpretation of cardiovascular diagnostic parameters.

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