Influence of ketamine or xylazine supplementation on isoflurane anaesthetized horses–a controlled clinical trial.

The research article explores the effects of adding ketamine or xylazine to isoflurane anesthesia in horses that are undergoing elective surgery. The researchers find that both ketamine and xylazine can reduce the quantity of isoflurane needed, as well as stabilize cardiovascular parameters, which could potentially lead to safer and more efficient anesthesia protocols for horses.

Research Setup

• This study was a controlled clinical trial in which 54 adult Warmblood horses were observed under three different anesthesia protocols during elective surgery.
• Each horse was premedicated with a combination of acepromazine, xylazine, and butorphanol, with anesthesia induced by ketamine-midazolam.
• Anesthesia was maintained with isoflurane alone in one group (I), while the rest of the horses were given isoflurane supplemented with either 1mg per kg per hour of ketamine (group IK) or the same dose of xylazine (group IX).
• The amount of isoflurane was adjusted by the same anesthesiologist in all cases using a scoring system. In order to maintain mean arterial pressure (MAP), dobutamine was used.
• Outcomes such as arterial blood gases, heart rate, respiratory rate, MAP, cardiac output, and recovery quality were recorded in the clinical trial.

Results

• The research found that both the groups getting ketamine (IK) and xylazine (IX) needed a significantly less volume percentage of isoflurane compared to the group that only received isoflurane (I).
• When xylazine was given (group IX), both the heart rate (HR) was notably lower and the mean arterial pressure (MAP) was significantly higher when compared to other groups.
• There were no statistically significant differences observed in other cardiopulmonary variables among the groups.
• All the horses recovered well, with the best recovery score observed in group IX.

Conclusions

• The researchers concluded that the infusion of either ketamine or xylazine, massively lowers the requirement of isoflurane and gives stable blood pressure on routine monitoring parameters.
• However, the study noted inconsistencies in measuring cardiac output due to lithium dilution, which means the results related to cardiac output should be questioned.
• The researchers recommend further repetitions of this study using a different method for measuring cardiac output to confirm these results.
• Irrespective of these inconsistencies, all the three protocols provided safe and clinically acceptable anesthesia with acceptable cardiovascular effects.