The influence of detomidine and epinephrine on heart rate, arterial blood pressure, and cardiac arrhythmia in horses.

This research studied the impact of detomidine and epinephrine on horses’ heart rate, blood pressure and cardiac arrhythmia. The researchers found that the use of detomidine can result in minor cardiac irregularities and increased blood pressure but the effects were not escalated with the addition of epinephrine.

Study Design and Methodology

• The researchers selected seven horses for this study. Two different dosages of detomidine (10 micrograms/kg and 20 micrograms/kg) were administered to these horses.
• For some of the tests, an infusion of epinephrine (0.1 microgram/kg/min) was begun 5 minutes before and ended 5 minutes after the detomidine was administered.
• The scientists closely observed the horses, noting down any changes in heart beat, blood pressure and cardiac arrhythmias.

Observations and Findings

• Upon administering detomidine, the researchers noticed one or more single supraventricular premature heartbeats in three out of seven horses. These are irregular heartbeats that occur when the heart’s upper chambers (the atria) beat too soon.
• The occurrence of cardiac arrhythmias did not increase with the addition of epinephrine to the detomidine.
• In some tests, the horse’s peak systolic blood pressure—measured at the point when the heart muscle contracts—increased after detomidine was administered alongside an epinephrine infusion.
• The maximum systolic arterial blood pressure observed was 290 mm Hg. However, this value is within the normal range observed in horses during maximum physical activity.
• The researchers also tested the blood of the studied horses for gases, arterial pH and excess base. They found that the infusion of epinephrine did not cause any significant changes in these parameters.

Conclusions

• The study concluded that while detomidine can cause minor cardiac irregularities and a slight increase in blood pressure in horses, these effects aren’t amplified with the addition of epinephrine.