Comparison of bupivacaine femoral and sciatic nerve block versus bupivacaine and morphine epidural for stifle surgery in dogs.

Objective: To evaluate the efficacy of combined femoral and sciatic nerve blocks as an alternative to epidural anesthesia and analgesia in dogs undergoing stifle surgery under general anesthesia.
Study Design: Prospective, blinded, randomized, clinical comparison.
Animals: Twenty dogs weighing 37 ± 11 (mean ± SD) kg, aged 3 (1-8) [median (minimum-maximum)] years undergoing elective unilateral tibial-plateau leveling osteotomy.
Methods: Dogs were assigned randomly to receive either epidural anesthesia (bupivacaine 0.5%, 0.5 mg kg(-1) + morphine 0.1%, 0.1 mg kg(-1), in 0.2 mL kg(-1); EPID) or femoral and sciatic nerve blocks (Bupivacaine 0.5%, 0.1 mL kg(-1), was administered at each site; F + S) guided by electrolocation. All patients received a standard general anesthesia technique. Pain and sedation were scored (on scales of 0-10 and 0-3, respectively) pre-operatively, at extubation, and at 1, 4 and then every 4 hours thereafter up to 24 hours. Postoperatively, hydromorphone was administered to any patient with a pain score of >5 or whenever the blinded caregiver determined that more hydromorphone was necessary. Intraoperative heart rate (HR), mean arterial pressure (MAP), end tidal isoflurane (FE'ISO), body temperature, post-operative pain scores, time to first hydromorphone dose after surgery, time to first feeding, time to first drinking, time to first urination, time to first ambulation (walk on a lead) and cumulative dose of hydromorphone were recorded.
Results: Intra-operatively, FE'ISO and MAP were significantly lower in the EPID group (p = 0.05 and p = 0.04, respectively). Postoperatively, the cumulative hydromorphone consumption (p = 0.04) and the incidence of urinary retention (p = 0.03) were higher in the EPID group.
Conclusion and Clinical Relevance: F + S is a practical alternative to EPID that produces less urine retention and reduces opioid consumption in the 24 hours after surgery. EPID might be associated with a lower isoflurane requirement and lower systemic blood pressure.
(© 2011 The Authors. Veterinary Anaesthesia and Analgesia. © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.)