The effects of detomidine, romifidine or acepromazine on echocardiographic measurements and cardiac function in normal horses.

This research article explores how the sedative drugs detomidine, romifidine, and acepromazine affect heart function and echocardiographic measurements in standardbred horses.

Research Methods

In this experiment, the researchers used an experimental study using a cross-over design without randomization. The subjects of the study were eight clinically normal Standardbred trotters.

• Echocardiographic evaluations were conducted across five separate days, using techniques like two-dimensional, guided M-mode and color Doppler.
• The researchers additionally collected heart rate data and standard limb lead electrocardiograms.
• Following this, the horses were sedated with either detomidine (0.01 mg kg(-1)), romifidine (0.04 mg kg(-1)), or acepromazine (0.1 mg kg(-1)) through intravenous administration, after which the same exams were repeated.

Results

• It was found that heart rates before treatment did not differ significantly between the three drugs (p = 0.98).
• Both detomidine and romifidine led to a significant drop in heart rate within the first 25 minutes following sedation; acepromazine’s effect on heart rate varied.
• Detomidine also significantly increased the left ventricular internal diameter in diastole and systole (p < 0.001), and significantly reduced the interventricular septum in systole, the left ventricular free wall in systole, and fractional shortening. The frequency of pulmonary regurgitation also significantly increased (p < 0.001).
• Romifidine caused a significant increase in the left ventricular internal diameter in systole and a significant decrease in the interventricular septum in systole and fractional shortening.
• Acepromazine did not have any significant effect on any of the measured parameters.

Conclusions and Clinical Relevance

• The results suggest that the sedation of horses using detomidine and, to a lesser extent, romifidine at the given doses can substantially affect heart function, as well as echocardiographic measurements of heart dimensions and the occurrence of valvular regurgitation.
• While these results may not have significant clinical implications, they do indicate that the possible effects of sedative drugs should be taken into account when interpreting echocardiographic variables in real-world cases.