Pimobendan is an inodilator (positive inotrope and vasodilator) used in the treatment of canine congestive heart failure (CHF). It has been used for this indication in Europe for over 5 years, and the FDA approved its use in dogs in the United States in 2006. This paper briefly reviews the 3 veterinary studies that have been published on pimobendan, as well as several abstracts and unpublished studies. It summarizes by stating that all authors seemed impressed by the rapidity with which the drug improves CHF in canine patients and that increased survival was noted consistently, particularly in Dobermans. Pimobendan thus appears promising, and further studies using larger groups are pending. Side effects of pimobendan are also discussed. In 1 study, adverse effects (tachycardia, left ventricular hypertrophy, diastolic dysfunction, and mitral regurgitation) were seen when the drug was inappropriately prescribed before onset of CHF. All of these effects resolved after the drug was stopped. Additionally, experimental toxicity data have shown mitral regurgitation to be induced when healthy dogs were given pimobendan. It is therefore concluded that pimobendan is more useful as CHF progresses in severity and that its use before onset of CHF cannot be recommended. Most veterinary cardiologists combine pimobendan with an angiotensin-converting enzyme inhibitor, although no data yet exist to support the superiority of the combination over either drug used alone.

Pimobendan in the treatment of canine heart disease: Early vs. late use? de Madron E. PROC 26TH ACVIM 136-137, 2008.