Mitral valve disease accounts for approximately 75% of all canine heart disease. However, the largest international clinical study of its kind was conducted among dogs with myxomatous mitral valve disease (MMVD) and had such positive results that it was ended early.

The study, "Evaluating Pimobendan In Cardiomegaly" (EPIC), evaluated the effectiveness of pimobendan in delaying the onset of clinical signs of congestive heart failure in dogs with increased heart size secondary to pre-clinical MMVD.

A mid-study analysis in mid-February 2015 indicated that pimobendan is clearly beneficial and did not raise any concern over the administration of pimobendan. Based on these results, the interim analysis committee recommended that the study be stopped, and the study was ended earlier this month.

"The results of this clinical trial have the potential to change the way the most common cause of heart disease and heart failure in the dog is managed on a day-to-day basis by veterinarians around the world," said Dr. Sonya Gordon, associate professor in the Department of Small Animal Clinical Science at the Texas A&M University College of Veterinary Medicine & Biomedical Sciences and one of the lead investigators.

The study was a prospective double-blind, randomized, placebo-controlled, international, multi-center clinical study—the so-called "gold standard" of clinical trials. Specialized veterinary cardiologists at 36 trial centers, half of which were in the United States, ran the trial. (The other 18 centers were in Australia, Canada, France, Germany, Italy, Japan, The Netherlands, Spain, Sweden, and the United Kingdom.)

The 360 canine patients enrolled in the trial were randomly allocated to either a pimobendan or a placebo treatment group, with 180 dogs in each group. Gordon and her colleagues at Texas A&M saw 16 of those dogs.

Full and final results of the study are expected at a later date.