Effects of postanesthetic sedation with romifidine or xylazine on quality of recovery from isoflurane anesthesia in horses.
OBJECTIVE
To test the hypothesis that postanesthetic sedation with romifidine would dose-dependently improve recovery quality of recovery from isoflurane anesthesia in horses more than postanesthetic sedation with xylazine.


METHODS
Prospective, randomized, blinded clinical trial.


METHODS
101 healthy adult horses examined at the University of California-Davis Veterinary Medical Teaching Hospital from 2007 to 2009.


METHODS
Horses were sedated with xylazine, and anesthesia was induced with guaifenesin, diazepam, and ketamine via a standardized drug protocol. Anesthesia for surgical or diagnostic procedures was maintained with isoflurane in oxygen for 1 to 4 hours. At the end of anesthesia, horses were moved to a padded stall for recovery. Once the breathing circuit was disconnected and the patient was spontaneously breathing, 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]) was administered i.v.. Objective patient, surgical, and anesthesia data were recorded. Subjective visual analog scale (VAS) scores of recovery quality were assigned by a single individual who was unaware of the treatment received. A stepwise linear regression model was used to correlate patient and procedure factors with the VAS score.


RESULTS
Painful procedures, longer anesthesia times, and the Arabian horse breed were associated with poorer VAS scores. Adjustment for these factors revealed an improved VAS recovery score associated with the use of a romifidine dose of 20 μg/kg.


CONCLUSIONS
In healthy adult horses anesthetized with isoflurane for > 1 hour, the results of this study supported the use of 20 μg of romifidine/kg, i.v., rather than lower romifidine doses or xylazine, for postanesthetic sedation to improve recovery quality.
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
Kerry J
KJ
Woodhouse
Robert J
RJ
Brosnan
Kyvan Q
KQ
Nguyen
Gale W
GW
Moniz
Larry D
LD
Galuppo
D000762:Anesthesia Recovery Period; D018685:Anesthetics, Inhalation / Q000009:adverse effects; D000818:Animals; D005260:Female; D006736:Horses / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D007530:Isoflurane / Q000009:adverse effects; D008297:Male; D014991:Xylazine / Q000008:administration & dosage / Q000494:pharmacology*
D018685:Anesthetics, Inhalation; D006993:Hypnotics and Sedatives; D007093:Imidazoles; D014991:Xylazine; C076257:romifidine; D007530:Isoflurane