A Clinical Trial about the Efficacy of Pimobendan in Comparison to Enalapril in Dogs with Mitral Valve Endocardiosis. Part 1: Clinical, Laboratory, Radiologic and Electrocardiographic Results
Aim of the study was to evaluate the effects of Pimobendan on clinical, laboratory, radiologic, electrocardiographic and echocardiograhic data in patients with naturally occurring mitral valve endocardiosis compared to Enalapril. Of special interest were adverse reactions to the drugs, such as arrhythmia or sudden death.
In this randomized blind study the effect of Enalapril in a single dose of 0,5 mg/kg body weight in comparison to Pimobendan in a dose of 0,5 mg/kg body weight divided twice daily was examined in dogs with mitral valve endocardiosis on day 0 (admission to the study), day 7 and day 28. In case of congestion, it was allowed to applicate Furosemide. Altogether 21 dogs in the Enalapril- and 19 dogs in the Pimobendan group were examined and the results interpreted. The data were collected on unsedated patients using the usual cardiologic standards on an outpatient basis.
Evaluating the clinical parameters we achieved similar improvements in both groups. The categorization to the NYHA-grades I - IV according to the New York Heart Association Guidelines based on these clinical parameters. Inside the groups we saw clear improvements. The comparison between the groups didn't show any significant difference. In the Pimobendan group we didn't see any adverse effect.
Statistically the laboratory examinations didn't show any significant difference in the Pimobendan group. Otherwise we found a significant increase (p < 0,05) of blood urea nitrogen concentrations in the Enalapril group. On day 7 and day 28 the average blood urea nitrogen concentration was above the reference range in this group.
The electrocardiography examinations did not indicate any type of arrhythmia. The mean heart rates remained inside the reference range in both groups. On day 28, a significant reduction (p < 0,05) of the heart rates in the Enalapril group occurred.
After 28 days of therapy the x-rays showed improved pulmonary fields in both groups. Although statistically significant (p < 0,05) more patients of the Enalapril group were treated with Furosemide, the comparison between the groups showed a significant better evaluation (p < 0,05) of the pulmonary fields in the Pimobendan group. Partially the improvements in both groups refered to the treatment with Furosemide.
The results show, that both, Enalapril and Pimobendan, can be administered effectively and safely in the treatment of mitral valve endocardiosis of the dog. An improvement was mainly visible on the basis of the clinical parameters. First of all the results should be valuated as tendencies, because of the short study period of 28 days. A clear statement could be done after a longer period of therapy with pimobendan. Therefore more studies with comparable patients over a longer study period should take place.