Cardiovascular effects of pimobendan in healthy mature horses.
Authors: Afonso T, Giguère S, Rapoport G, Barton M H, Coleman A E
Journal: Equine veterinary journal
Summary
# Cardiovascular Effects of Pimobendan in Healthy Mature Horses Pimobendan, an inodilator routinely used in canine cardiology, remains largely unexplored in equine practice despite its potential value in managing equine heart failure. To establish a foundation for rational clinical use, Afonso and colleagues administered pimobendan intravenously or intragastrically to five healthy horses in a randomised crossover design, measuring right ventricular pressures, arterial blood pressure, central venous pressure, cardiac output and heart rate at multiple time points up to 8 hours post-administration. Both routes of administration produced significant increases in heart rate (approximately 33–36%), whilst intravenous pimobendan additionally increased the maximum rate of pressure development in the right ventricle by 35% and decreased minimum and end-diastolic pressures by 47% and 34% respectively; no adverse effects were observed in any treatment group. These positive chronotropic and inotropic responses indicate that pimobendan warrants investigation as a therapeutic agent for equine heart failure, though practitioners should note that oral absorption appears adequate and the drug produces measurable haemodynamic changes comparable to those desired in failing hearts. Further studies in horses with documented cardiac pathology are needed before clinical recommendations can be made, but this baseline safety and efficacy data removes a significant barrier to future therapeutic evaluation.
Read the full abstract on PubMed
Practical Takeaways
- •Pimobendan shows promise as an inodilator for equine heart failure management, with intravenous administration demonstrating clear positive chronotropic and inotropic effects in healthy horses
- •Further clinical trials in horses with actual heart disease are needed before implementing pimobendan into standard therapeutic protocols for equine cardiac cases
- •Practitioners should be aware that this small pilot study establishes safety and basic cardiovascular effects, but efficacy and optimal dosing in diseased horses remain to be determined
Key Findings
- •Pimobendan administered intravenously increased heart rate by 36±14% compared to placebo (-2±7%), demonstrating significant positive chronotropic effects
- •Intravenous pimobendan increased maximum rate of increase in right ventricular pressure by 35±36% and decreased minimum and end diastolic pressures (47±24% and 34±13% respectively) compared to placebo
- •Both intravenous and intragastric pimobendan routes produced significant heart rate increases, though only intravenous administration showed significant changes in contractility parameters
- •No adverse effects were observed with pimobendan administration in healthy mature horses