Inotropic effects of a single intravenous recommended dose of pimobendan in healthy dogs

Abstract

We investigated the effects of an injectable pimobendan solution (0.15 mg/kg) on cardiac function in healthy dogs. Fifteen dogs were divided into placebo, intravenous pimobendan injection, and subcutaneous pimobendan injection groups. In the placebo, the heart rate, systolic and end-diastolic left ventricular pressure (LVPs and LVEDP), and peak positive (max dP/dt) and negative (min dP/dt) first derivatives of the left ventricular pressure did not change for 60 min. After the intravenous pimobendan injection, LVEDP decreased significantly within 5 min, while the max dP/dt increased, and the effects continued until 60 min. In comparison, there were no hemodynamic changes after the subcutaneous pimobendan injection. This study demonstrates that injectable pimobendan induced a rapid inotropic effect and decreased the LVEDP in dogs.

Keywords: canine; heart failure; phosphodiesterase inhibitor; pimobendan; systolic function.

Fig. 1.

Changes in heart rate, LVPs, and LVEDP with the intravenous administration of pimobendan. Data are shown as the means ± standard deviation. BL, baseline; LVPs, peak systolic LV pressure; LVEDP, end-diastolic LV pressure. *P<0.05 vs. baseline.

Fig. 2.

Changes in max dP/dt and min dP/dt with the intravenous administration of pimobendan. Data are shown as the means ± standard deviation. BL, baseline; max dP/dt, the peak positive first derivatives of the LV pressure; min dP/dt, the peak negative first derivatives of the LV pressure. †P<0.01 vs. baseline, ‡P<0.001 vs. baseline.