Effects of a Single Intra-Articular Injection of 2% Lidocaine or 0.5% Bupivacaine on Synovial Fluid Acute Phase Protein Concentrations in Healthy Horses

The purpose of this study was to compare the extent of inflammation response in the middle carpal joints of healthy horses following intra-articular injection of 2% lidocaine, 0.5% bupivacaine, or 0.9% saline solu-tion. The right middle carpal joint of 20 horses was injected with 5 mL of 0.5% bupivacaine (GB, n = 10) or 5 mL of 2% lidocaine (GL, n = 10). The left middle carpal joint of horses was used as a control (5 mL 0.9% saline). Serum and synovial fluid (SF) were aseptically collected before and at predetermined times after each injection. Serum and synovial fluid protein, albumin, transferrin, haptoglobin, ceruloplasmin, alpha 1-antitripsin, and alpha 1-acid glycoprotein concentrations were measured by sodium dodecyl sulfate poly-acrylamide gel electrophoresis and compared among treatments. The results were submitted to analysis of variance using the SAS statistical program, and means were compared by the Student-Newman-Keuls test ( P < .05). Both lidocaine and bupivacaine induced serum and SF changes indicative of inflamma-tion, but the magnitude of those changes was more pronounced for lidocaine. Administration of 0.9% saline also induced an inflammatory reaction, but the magnitude of these changes was less pronounced than those caused by GB and GL. The results suggested that bupivacaine is safer than lidocaine for intra-articular injection in horses. Saline solution should not be used as an adjunct to intra-articular injections in horses. (c) 2023 Elsevier Inc. All rights reserved.