Evaluation of infusions of xylazine with ketamine or propofol to modulate recovery following sevoflurane anesthesia in horses.

This research paper evaluates whether the infusion of xylazine with either ketamine or propofol can improve the recovery of horses after sevoflurane anesthesia. The study finds that such infusions do significantly enhance recovery quality but necessitate careful monitoring of oxygenation and ventilation.

Objective of the study

• The main purpose of the research was to ascertain if the quality of recovery from sevoflurane anesthesia in horses can be improved by using infusions of xylazine combined with either propofol or ketamine.

Methodology

• The study was conducted with six healthy adult horses. Each animal underwent anesthesia three times at one-week intervals.
• Anesthesia was first induced with xylazine, diazepam, and ketamine before being maintained with sevoflurane for around 90 minutes. Of these, the last 60 minutes were under steady-state conditions.
• For one episode, each horse was allowed to recover from the sevoflurane anesthesia. For the other two episodes, infusions of either xylazine-ketamine or xylazine-propofol were administered after discontinuing the sevoflurane.
• The chosen cardiopulmonary variables were measured during anesthesia and recovery, and recovery events were monitored and evaluated subjectively.

Results

• The study showed that the cardiopulmonary variables differed minimally among the treatments, but there was greater respiratory depression with the xylazine-propofol infusion compared to the xylazine-ketamine infusion.
• Although the interval from the discontinuation of sevoflurane or infusion to standing did not significantly differ among the treatments, the xylazine-propofol infusion required significantly fewer attempts to stand successfully compared to sevoflurane alone.
• The scores for recovery from anesthesia were significantly lower (indicating a better recovery) after either infusion, compared to scores for sevoflurane administration alone.

Conclusions

• Both the xylazine-ketamine and xylazine-propofol infusions significantly improved the quality of recovery from sevoflurane anesthesia in the horses.
• The findings suggest that such infusions could provide the benefit of a smoother recovery following sevoflurane anesthesia, especially in horses requiring such critical care.
• However, the authors recommend careful monitoring of oxygenation and ventilation due to the higher respiratory depression risk posed by the xylazine-propofol infusion.