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

Abstract

ObjectiveTo 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 designProspective, blinded, randomized, clinical comparison. AnimalsTwenty dogs weighing 37 ± 11 (mean ± SD) kg, aged 3 (1–8) [median (minimum–maximum)] years undergoing elective unilateral tibial-plateau leveling osteotomy. MethodsDogs 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. ResultsIntra-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.