The recovery of horses from inhalant anesthesia: a comparison of halothane and isoflurane.
Authors: Donaldson L L, Dunlop G S, Holland M S, Burton B A
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Halothane versus Isoflurane Recovery in Equine Surgery Recovery from general anaesthesia represents a critical period for equine patients, yet few studies have directly compared the emergence characteristics of commonly used inhalant agents. Donaldson and colleagues conducted a randomised, blinded clinical trial on 99 racehorses undergoing arthroscopic surgery, assessing recovery quality using a standardised 10-category scoring system that evaluated attitude, purposeful activity, coordination, strength and balance from extubation through to standing. Whilst horses anaesthetised with isoflurane reached both sternal recumbency and standing substantially faster—approximately 13 minutes sooner to sternal recumbency and 13 minutes sooner to standing—they demonstrated notably lower recovery scores (median 27.5 versus 20.0), indicating a more agitated, uncoordinated emergence despite similar extubation times between groups. For practitioners balancing speed of recovery against quality and composure, these findings suggest halothane produces a calmer, more controlled emergence, whereas isoflurane facilitates faster mobilisation at the expense of recovery smoothness; importantly, all horses recovered without serious injury regardless of agent used, allowing the choice to be individualised based on surgical requirements and facility protocols.
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Practical Takeaways
- •If rapid post-operative recovery is critical, isoflurane enables horses to stand ~13 minutes sooner, but expect a less controlled, more restless emergence
- •Halothane provides a calmer, more controlled recovery despite taking longer to stand—consider this trade-off based on your facility's post-operative management capabilities
- •Both agents are safe for arthroscopic procedures in racehorses; choice should balance recovery speed against emergence quality and your ability to manage a potentially more agitated horse
Key Findings
- •Horses recovering from isoflurane achieved sternal recumbency 13 minutes faster than halothane-recovered horses (24.7 vs 37.7 minutes)
- •Horses recovering from isoflurane stood 13 minutes faster than halothane-recovered horses (27.6 vs 40.6 minutes)
- •Halothane-recovered horses had lower recovery scores (median 20.0) indicating more composed recovery compared to isoflurane (median 27.5)
- •Both agents resulted in safe recovery with no significant injuries despite differences in recovery quality and speed