Effects of postanesthetic sedation with romifidine or xylazine on quality of recovery from isoflurane anesthesia in horses.

This study examines whether the use of romifidine for post-anesthetic sedation in horses improves their recovery from isoflurane anesthesia better than xylazine. The results suggest that, especially for painful processes and longer anesthesia times, romifidine does improve recovery quality.

Research Methods

• The study was a prospective, randomized, blinded clinical trial conducted on 101 healthy adult horses at the University of California-Davis Veterinary Medical Teaching Hospital between 2007 and 2009.
• The horses first received sedation with xylazine, and then anesthesia was induced using guaifenesin, diazepam, and ketamine following a standard protocol.
• Anesthesia for medical or diagnostic procedures was maintained with isoflurane in an oxygen mixture for anywhere from 1 to 4 hours.
• At the end of anesthesia, the horses were moved to a padded stall for recovery, and once they started breathing independently, they were administered either xylazine (100 or 200 μg/kg [45 or 91 μg/lb]) or romifidine (10 or 20 μg/kg [4.5 or 9.1 μg/lb]) through an intravenous route.
• The researchers collected data regarding the patients, surgical procedures, and anesthesia. Subjective quality of recovery scores (VAS scores) were assigned by an individual who was not aware of the treatment given.
• A stepwise linear regression model was used to correlate patient and procedure factors with the recovery score.

Results of the Study

• The results showed that painful procedures, longer anesthesia times, and the Arabian horse breed correlated with poor recovery scores.
• After adjustment for these factors, it was demonstrated that a dose of 20 μg/kg romifidine improved the recovery score.

Conclusions of the Study

• The study supports the use of 20 μg of romifidine/kg, administered intravenously, over lower doses of romifidine or xylazine for post-anesthetic sedation in horses that have been under isoflurane anesthesia for more than an hour.
• This suggests romifidine may be more effective in improving recovery quality from anesthesia in horses, especially in potentially painful or longer-lasting procedures.