RESUMO
OBJECTIVES: To document efficacy of intra-articular mepivacaine in dogs based on the hypothesis that this would blunt the haemodynamic response to a nociceptive stimulus (arthroscopic surgery), reducing interventional analgesia requirements. METHODS: A dose of mepivacaine 2% 0 · 1 ml/kg (2 mg/kg) was injected intra-articularly into one randomly assigned elbow joint before surgery in eight dogs undergoing bilateral elbow arthroscopy. Baseline haemodynamic measurements were recorded immediately before the start of each arthroscopic procedure and repeated at arthrocentesis, saline distension of the joint, incision, arthroscopic cannula and obturator insertion and placement of the second portal and haemodynamic variability calculated. If baseline parameters increased by more than 20% suggesting nociception, 1 µg/kg fentanyl was administered intravenously. RESULTS: Significantly less fentanyl was required during arthroscopy on the mepivacaine treated elbows compared to the non-treated elbows (P = 0 · 003) and the time to first fentanyl administration was significantly longer (P = 0 · 0001) in the mepivacaine treated elbows (21 · 2 ± 4 · 9 minutes) compared to the non-treated elbows (6 · 1 ± 2 · 3 minutes). Haemodynamic variability was significantly reduced in the mepivacaine group (heart rate P = 0 · 04, mean arterial pressure P = 0 · 003). CLINICAL SIGNIFICANCE: Intra-articular mepivacaine blunts the haemodynamic response to arthroscopic surgery in dogs and reduces interventional analgesia requirement.