Influence of the combination of butorphanol and detomidine within premedication on the preoperative sedations score, the intraoperative cardiovascular situation and the early recovery period in horses

Abstract

To examine the influence of a preanaesthetic sedation with butorphanol and detomidine on the degree of sedation, consumption of isoflurane and cardiovascular parameters as well as on the recovery period, patients of the Clinic for Horses, University of Veterinary Medicine Hannover, (n = 40) were randomised and blinded assigned to two groups. One half received 0.01 mg/kg bw detomidine and additionally 0.025 mg/kg bw butorphanol and the other half of the horses received detomidine in a dose of 0.025 mg/kg bw. Introduction (0.05 mg/kg diazepam and 2.2 mg/kg ketamine) and maintenance (isoflurane in oxygene) of anaesthesia were standardised in both groups. The analysed period of the anaesthesia started 20 minutes after induction and the data processed by analysis of the variance were collected up to the end of anaesthesia. The following parameters were recorded during general anaesthesia: arterial blood pressure, heart frequency, breathing frequency, inspiratory oxygen and expiratory isoflurane concentration. The preoperatively scored sedation degree was positively influenced by combination of butorphanol and detomidine in contrast to detomidine alone, even though the dosage of the sedative detomidine was considerably reduced for the combination with butorphanol. The arterial blood pressure was over the whole period of anaesthesia higher in horses receiving the combination of butorphanol and detomidine (p = 0.08) and a significant decreased consumption of isoflurane (p = 0.04) was detected in the some group. The duration and quality of recovery period were recorded postoperatively. Horses of the butorphanol/detomidine group showed a slightly shorter recovery period of equal quality probably due to less isoflurane consumption and lower dose of detomidine preoperatively. If combined with butorphanol the dosage of detomidine can be considerably reduced for premedication. The results of this study show that in equine elective surgery the combination of butorphanol with detomidine may improve the intraoperative cardiovascular situation and decrease the consumption of inhalant anaesthetics in contrast to premedication with detomidine alone. There were no significant differences between the sedation scores or quality and duration of the recovery periods between both groups.