Clinical evaluation of acepromazine, xylazine and butorphanol in different combinations for standing sedation in horses

The objective of this study was to compare four combinations of acepromazine, xylazine and butorphanol in adult horses for sedative and clinicophysiological effects. 24 adult, mixed-breed horses of either sex, weighing 200–400 kg were divided into four groups of six animals each. The animals of group A received a mixture of acepromazine (0.04 mg/kg b.wt) and butorphanol (0.02 mg/kg b.wt), animals of group B received a mixture of xylazine (0.5 mg/kg b.wt) and butorphanol (0.02 mg/kg b.wt). Group C animals received a mixture of acepromazine (0.04 mg/kg b.wt) and xylazine (0.5 mg/kg b.wt), and the animals of group D were administered with a mixture of acepromazine (0.03 mg/kg b.wt), xylazine (0.5 mg/kg b.wt) and butorphanol (0.02 mg/kg b.wt). All the drugs were mixed in the same syringe and administered slowly through an i.v. catheter placed in jugular vein. To objectively assess the depth of sedation, a variety of behavioural and clinical parameters were recorded and scored. Among the four groups, highest sedation score was observed in the animals of group D. All four combinations induced significant decrease in heart rate, respiratory rate and mean arterial blood pressure. Body temperature and SpO₂ were also decreased. The values returned to normal during recovery. All of these sedative drug regimens can safely be used in horses.