The effects of xylazine or detomidine when used as a pre-anesthetic sedative on recovery quality and duration in horses undergoing elective equine castration.

The purpose of this prospective, blinded, randomized clinical trial was to compare the effects of low dose detomidine to xylazine on recovery quality and duration in a castration procedure. Horses were administered either detomidine [0.015 mg/kg body weight (BW)] or xylazine (1.1 mg/kg BW) intravenously (IV) before IV induction with ketamine (2.2 mg/kg BW) and diazepam (0.05 mg/kg BW). Two anesthesiologists who were unaware of treatment allocation scored the recoveries using a simple descriptive scale (with a low number representing the most desirable recovery) and recoveries were timed. Horses in the detomidine group (n = 16) had a median recovery score of 16 (range: 11 to 26), whereas horses in the xylazine group (n = 12) had a median recovery score of 12 (range: 10 to 16) (P = 0.001). There was no difference in surgery time (P = 0.52), time from the end of surgery to standing (P = 0.45), or time from induction to standing (P = 0.48) between the groups.