A prospective multi-centre clinical trial to compare buprenorphine and butorphanol for postoperative analgesia in cats

One hundred and fifty-three cats undergoing surgery in seven veterinary practices in Great Britain were studied. They were randomly allocated to receive either 10-20 μg/kg buprenorphine or 0.4 mg/kg butorphanol with acepromazine before anaesthesia with propofol, Saffan or thiopentone and isoflurane or halothane. Routine monitoring was undertaken. Pain and sedation were assessed blind using a four point (0-3) simple descriptive scale (SDS) at 1, 2, 4, 8 and 24 h. Pain and sedation data were compared using non-parametric statistical tests and continuous data using t tests or analysis of variance (ANOVA). Anaesthesia and surgery were uneventful, and cardiorespiratory data were within normal limits. After surgery, overall, more cats had pain score 0 after buprenorphine and more had pain score 3 after butorphanol (P = 0.0465). At individual time points, more cats had lower pain scores after buprenorphine at 2 (P = 0.040) and 24 (P = 0.036) h. At 24 h 83% after buprenorphine and 63% after butorphanol had pain score 0 (P < 0.04). Buprenorphine provided better and longer lasting postoperative analgesia than butorphanol.