A randomized clinical trial comparing butorphanol and buprenorphine within a multimodal analgesic protocol in cats undergoing orchiectomy

Abstract

Objectives The aim of this study was to compare the effects of butorphanol and buprenorphine, as part of a multimodal analgesic protocol, on recovery and analgesia in cats undergoing orchiectomy. Methods In a prospective, randomized, blind clinical trial, 47 adult male cats were randomly assigned to receive either butorphanol (0.3 mg/kg, n = 24) or buprenorphine (0.02 mg/kg, n = 23) in combination with dexmedetomidine (25 μg/kg) and alfaxalone (2 mg/kg) as a single intramuscular injection for the induction of general anesthesia. Isoflurane carried in oxygen was supplemented as needed during orchiectomy. All cats received lidocaine (2 mg/kg intratesticular), meloxicam (0.3 mg/kg SC) and atipamezole (125 μg/kg IM) postoperatively. Pain and sedation scales were applied at baseline, and 2, 4 and 6 h postoperatively. Time to achieve sternal recumbency and to begin eating were also recorded. Results Pain scale scores were low and showed no difference between the treatment groups at all time points ( P ⩾0.99, all time points). Four cats exceeded the analgesia intervention threshold for rescue analgesia (butorphanol, n = 3; buprenorphine, n = 1). There was no difference in sedation scores between groups at any time point ( P >0.99, all time points). Significantly more cats in the buprenorphine group (n = 12) required isoflurane than in the butorphanol group (n = 2) ( P = 0.0013; relative risk 6.3, 95% confidence interval [CI] 1.8–23.5). There was no significant difference in time to achieve sternal recumbency ( P = 0.96, 95% CI –20 to 20) between groups or in return to eating ( P = 0.48, 95% CI –92.0 to 113.5), with most cats eating within 1 h of surgery (butorphanol, 79%; buprenorphine, 83%). Conclusions and relevance There were no significant differences in analgesia or recovery between butorphanol and buprenorphine treatment groups as part of a multimodal injectable anesthetic protocol. Butorphanol is associated with superior depth of anesthesia, facilitating injectable anesthesia.