The study was undertaken on the 12 healthy horses to evaluate the sedative effect of two different doses of acepromazine maleate prior to xylazine-ketamine anaesthesia for gelding. These horses were randomly divided into two equal groups. Acepromazine maleate 0.02 mg/kg and 0.04 mg/kg was used as preanaesthetic in group I and group II, respectively, prior to intravenous injection of xylazine (1 mg/kg) and ketamine (1.5 mg/kg). The horses of group-I showed moderate signs of sedation, whereas deep sedation was shown by horses of group-II. Induction of anaesthesia was recorded in 158.16±3.22 and148.6±3.08 s in group I and group II, respectively. Quality of induction of anaesthesia and degree of muscle relaxation were better in group II than in group I. Duration of anaesthesia was 11.5±0.34 and 13.33±0.66 min in groups I and II, respectively. Time of recovery was 37.8±1.01 and 40.5±0.85 min in groups-I and II, respectively. Respiratory rate decreased significantly during anaesthesia in both groups, whereas, rectal temperature and heart rate showed non-significant difference during anaesthesia in both groups. In both groups, non-significant difference was noted in total erythrocyte count, total leukocyte count, haemoglobin level and in packed cell volume. Liver function test and kidney function test also showed non-significant difference in both groups. It was concluded that acepromazine @ 0.02 mg/kg produces moderate sedation, whereas, acepromazine @ 0.04 mg/kg produces deep sedation in horses. The combination of acepromazine (0.04 mg/kg), xylazine (1 mg/kg) and ketamine (1.5 mg/kg) produces better quality of anaesthesia.
