The recovery of horses from inhalant anesthesia: a comparison of halothane and isoflurane.

The research investigates the recovery rates and quality of racehorses after undergoing anesthesia using two different inhalant anesthetics: halothane and isoflurane. The findings reveal faster but less composed recovery in horses anesthetized with isoflurane compared to those anesthetized with halothane.

Study Design and Methods

• This was a prospective, randomized blinded clinical trial involving 99 racehorses – 96 Thoroughbred and 3 Standardbred – undergoing elective distal forelimb arthroscopy.
• The horses were premedicated with intravenous xylazine, induced with guaifenesin and ketamine, and maintained on an anesthetic circle system equipped with a vaporizer specific to the agent.
• A blinded scorer undertook recovery management following a standardized protocol. The scoring system included ten categories for assessing overall attitude, purposeful activity, muscle coordination, strength, and balance from the horses’ arrival in recovery till they stood upright.
• Recording included the times to extubation (removal of the breathing tube), sternal recumbency (the animal lying on its chest), and standing. The median recovery scores and mean times were then compared using appropriate statistical tests.

Results

• The median recovery score was lower for horses recovering from halothane anesthesia (20.0; range, 10 to 57) than those recovering from isoflurane anesthesia (27.5; range, 10 to 55).
• The average extubation times were similar for both groups. But the horses anesthetized with isoflurane achieved sternal recumbency and stood upright more quickly than those anesthetized with halothane.

Conclusions

• The recovery of horses from isoflurane anesthesia was faster but less composed than the recovery of those from halothane anesthesia.
• According to the parameters used in this study, the quality of recovery was weaker after isoflurane than after halothane. Despite this, the range of recovery scores was not dissimilar between both groups and all horses recovered without significant injury.

From this research, veterinary practitioners get critical insights about post-operative management and recovery of horses from anesthesia, contributing to improved equine health outcomes.