Opioids are considered to provide effective perioperative analgesia for acute surgical pain of which buprenorphine and methadone are most commonly used in clinical practice. The aim of our research was to compare the analgesic efficacy of methadone and buprenorphine in dogs and cats undergoing ovariohysterectomy, to help guide clinicians in their decision making regarding opioid choice for ovariohysterectomy and other moderate to severely painful procedures.
In dogs undergoing ovariohysterectomy, a premedication of methadone or buprenorphine combined with acepromazine or medetomidine was administered intramuscularly and anaesthesia induced with propofol. In cats undergoing ovariohysterectomy, methadone or buprenorphine combined with ketamine, midazolam and medetomidine (QUAD protocol) was administered intramuscularly and no induction agent was required. Anaesthesia was maintained with isoflurane in both cats and dogs. Pain was assessed regularly postoperatively using a species-specific composite pain scale (SF-GCPS in dogs and CMPS-F in cats) and the Dynamic Interactive Visual Analogue Scale (DIVAS). Rescue analgesia (methadone) was administered intramuscularly if indicated by the composite scale pain score.
Both dogs and cats showed that methadone groups required less rescue analgesia (p = 0.02 in dogs; p = 0.04 in cats). Dogs administered methadone showed lower overall SF-GCPS pain scores (p < 0.001) and DIVAS pain scores (p < 0.01) compared to buprenorphine groups. Cats administered methadone also showed lower over CMPS-F pain scores for methadone groups compared to buprenorphine groups (p = 0.04), however, there was no difference in postoperative DIVAS scores between buprenorphine and methadone groups (p = 0.06).
We concluded that overall preoperative methadone provides better postoperative analgesia compared to buprenorphine in the context of ovariohysterectomy and this is likely to be true for other moderate to severely painful procedures in both dogs and cats.
|Date of Award||25 Sep 2018|
- The University of Bristol
|Supervisor||Jo Murrell (Supervisor), James Hunt (Supervisor) & David Yates (Supervisor)|