Antinociceptive activity of pre- versus post-operative intra-articular bupivacaine in goats undergoing stifle arthrotomy

Abstract

ObjectiveTo evaluate the peri-operative analgesic efficacy of intra-articular bupivacaine administered before or after stifle arthrotomy. Study designProspective, randomized, blind, placebo-controlled experimental trial. AnimalsThirty-nine healthy goats. MethodsThe goats were allocated randomly to one of three intra-articular treatment groups: group PRE (bupivacaine before and saline after surgery), group POST (saline before and bupivacaine after surgery) and group CON (saline before and after surgery). Anaesthesia was maintained with a constant end-tidal sevoflurane of 2.5%. Intra-operatively heart rate (HR), respiratory rate and mean arterial blood pressure (MAP) after critical surgical events (CSE) were recorded and compared with pre-incision values. Propofol requirements to maintain surgical anaesthesia were recorded. Flunixin was administered for 5 days. Post-operative pain assessment at 20 minutes, 2 hours, 4 hours after recovery and on day 2 and 3 included a multidimensional pain score (MPS), a lameness score and mechanical nociceptive threshold (MNT) testing. Rescue analgesia consisted of systemic opioids. Data were analysed using Kruskal–Wallis, Mann–Whitney, Friedman or chi-square tests as appropriate. ResultsIntra-operatively, group PRE had lower HR and MAP at several CSEs than groups POST/CON and required less propofol [0 mg kg−1 (0–0 mg kg−1)] than group POST/CON [0.3 mg kg−1 (0–0.6 mg kg−1)]. Post-operatively, group POST had significantly higher peri-articular MNTs than groups PRE and CON up to 4 hours after recovery. No treatment effect was detected for MPS, lameness scores and rescue analgesic consumption at any time point. Conclusions and clinical relevancePre-operative intra-articular bupivacaine provided notable intra-operative analgesia in goats undergoing stifle arthrotomy but did not reduce post-operative pain. Post-operative intra-articular bupivacaine provided a short lasting reduction of peri-articular hyperalgesia without affecting the requirements for systemic analgesia. Multimodal perioperative pain therapy is recommended to provide adequate analgesia for stifle arthrotomy in goats.