Comparison of clinical effects of epidural levobupivacaine morphine versus bupivacaine morphine in dogs undergoing elective pelvic limb surgery

Objective To evaluate the efficacy, in terms of the amount of rescue analgesia required, and the clinical usefulness of epidural injection of morphine with bupivacaine or levobupivacaine for elective pelvic limb surgery in dogs during a 24-hour perioperative period. Study design Prospective, blinded, randomized clinical study. Animals A group of 26 dogs weighing 31.7 +/- 14.2 (mean +/- standard deviation) kg and aged 54 +/- 36 months. Methods All dogs were premedicated with methadone intravenously (0.2 mg kg(-1)) and anaesthesia induced with diazepam (0.2 mg kg(-1)) and propofol intravenously to effect. After induction of anaesthesia, dogs randomly received a lumbosacral epidural injection of morphine 0.1 mg kg(-1)Z with either levobupivacaine 0.5% (1 mg kg(-1); group LevoBM) or bupivacaine 0.5% (1 mg kg(-1); group BM). Cardiovascular, respiratory and temperature values were recorded during the intraand postoperative period. A visual analogue scale, subjective pain scale, sedation scale and the short form of the Glasgow pain scale were assessed every 6 hours after epidural injection during 24 hours. The ability to stand and walk, neurological deficits and other side effects were assessed at the same time points. The amount of rescue analgesia (sufentanil intraoperatively and methadone postoperatively) was recorded. Results No statistically significant differences were found between groups for any of the recorded data, with the exception of the incidence of spontaneous urination and postoperative rescue analgesia requirement. In group LevoBM four dogs spontaneously urinated at recovery while none of the dogs in group BM did (p = 0.03) and seven dogs of group LevoBM required postoperative rescue analgesia versus none of the dogs in the BM group (p = 0.005). Conclusions and clinical relevance Epidural Levo-BM is a suitable alternative to BM in healthy dogs during elective pelvic limb surgery. Epidural BM produced more urinary retention but better pain control compared to the same concentration and dose of LevoBM in dogs.