Evaluation of the use of midazolam as a co-induction agent with ketamine for anaesthesia in sedated ponies undergoing field castration.

This research investigates the effectiveness and safety of using midazolam along with ketamine for anaesthesia during the field castration of sedated ponies. The study found that this combination improved the quality of anaesthetic induction, ease of the tracheal intubation process, and surgical muscle relaxation without affecting the quality of recovery.

Methodology

• 38 ponies undergoing field castration were randomly assigned into two groups i.e. group M (midazolam) and group P (placebo) for a double-blind, placebo-controlled trial.
• Each pony first received an intravenous injection of detomidine (20 μg/kg). Following that, group M received midazolam (0.06 mg/kg) with 2.2 mg/kg ketamine for anaesthetic induction while group P received placebo with ketamine.
• Several factors were assessed including the quality of anaesthesia induction, endotracheal intubation (insertion of a tube through the mouth and then airway for ventilation), surgical relaxation, and recovery.
• Timings for key stages in the procedure were recorded, and cardiorespiratory variables were also assessed every five minutes.
• Any adverse effects were documented throughout the study.
• Data was tested for normality and analysed using mixed model ANOVA, Fisher’s exact test, unpaired Students’ t-test and Wilcoxon Rank-sum as appropriate.

Results

• The group M had better induction, intubation, and surgical relaxation scores.
• Group M required fewer additional doses of detomidine and ketamine.
• The period from induction to the first movement, sternal recumbency (resting on the chest), and standing was longer in group M.
• Recoveries were uneventful with no differences in quality between both groups.

Conclusions

• The research was a field study and involved non-invasive monitoring techniques.
• The use of midazolam along with ketamine as co-inducing agents improved the process of induction, intubation, and surgical muscle relaxation without affecting recovery quality. Thus, indicating that ketamine-midazolam co-induction could be a viable method for anaesthesia in field castrations.