Objective To identify if synovial fluid prostaglandin E2 increases in response to a single intra-articular dose of bupivacaine in the normal canine stifle.

            Results
            There were no significant differences in synovial fluid prostaglandin E2 (PGE2) concentrations between treatment groups or over time within bupivacaine or saline groups. Samples requiring ≥ 3 arthrocentesis attempts had significantly higher PGE2 concentrations compared to samples requiring 1 or 2 attempts. Following correction for number of arthrocentesis attempts, PGE2 concentrations were significantly higher than baseline at 24 and 48 h in the bupivacaine group; however there were no significant differences between the bupivacaine and saline groups. In normal dogs, a single bupivacaine injection did not cause significant synovial inflammation, as measured by PGE2 concentrations, compared to saline controls. Future research should minimize aspiration attempts and include evaluation of the synovial response to bupivacaine in clinical cases with joint disease.