• Open Access

The Effect of Pimobendan on Left Atrial Pressure in Dogs with Mitral Valve Regurgitation


Corresponding author: Ryou Tanaka, DVM, PhD, 3-5-8 Saiwaicho, Fuchu-shi, Tokyo 183-8509, Japan; e-mail: ryo@vet.ne.jp



The effects of pimobendan on left atrial pressure (LAP) in dogs with mitral valve disease (MR) have not been documented in a quantitative manner.


The objective was to document and study the short-term effects of pimobendan on LAP and echocardiographic parameters in MR dogs.


Eight healthy Beagle dogs weighing 10.0–14.7 kg (3 males and 5 females; aged 2 years) were used.


Experimental, cross-over, and interventional study. Dogs with surgically induced MR received pimobendan at either 0.25 mg/kg or 0.50 mg/kg PO q12h for 7 days and then, after a 7-day wash-out period, the other dosage. LAP was measured for 30 minutes at baseline and again on days 1, 2, 4, and 7 of pimobendan administration.


Mean LAP was significantly decreased after the administration of 0.25 mg/kg (15.81 ± 5.44 mmHg to 12.67 ± 5.71 mmHg, P < .001) and 0.50 mg/kg (15.76 ± 5.45 mmHg to 10.77 ± 5.23 mmHg, P < .001). Also, the 0.50 mg/kg group led to a significantly lower LAP (P < .01) compared with the 0.25 mg/kg group. Significant reduction was seen for the first time 4 days after the administration of 0.25 mg/kg and a day after the administration of 0.50 mg/kg.

Conclusions and Clinical Importance

Pimobendan decreased LAP in a dose-dependent manner in dogs with acute MR caused by experimental chordal rupture. This study did not evaluate adverse effects of high-dose pimobendan, and additional studies in clinical patients are warranted.