Effects of a Single Intra-Articular Injection of 2% Lidocaine or 0.5% Bupivacaine on Synovial Fluid Acute Phase Protein Concentrations in Healthy Horses.
Authors: Dos Santos Gabriel Carvalho, Di Filippo Paula Alessandra, da Fonseca Leandro A, Quirino Célia Raquel
Journal: Journal of equine veterinary science
Summary
Intra-articular local anaesthetics are routinely used in equine practice for diagnostic and therapeutic joint procedures, yet their inflammatory potential remains incompletely characterised. This Brazilian study directly compared the synovial inflammatory response to 2% lidocaine versus 0.5% bupivacaine injected into the middle carpal joints of 20 healthy horses, with contralateral saline controls, measuring acute phase proteins (haptoglobin, ceruloplasmin, α1-antitrypsin, and α1-acid glycoprotein) in both serum and synovial fluid at multiple timepoints using protein electrophoresis. Lidocaine triggered significantly greater increases in acute phase protein concentrations than bupivacaine, whilst saline injection itself also provoked a measurable inflammatory response—albeit less pronounced than either local anaesthetic—suggesting the needle trauma alone accounts for baseline inflammation. For practitioners, these findings support bupivacaine as the safer choice for intra-articular anaesthesia in horses, particularly for joint procedures where minimising inflammation is a priority, whilst the unexpected reactivity of saline warrants reconsideration of its use as a diluent or flushing agent during joint injections.
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Practical Takeaways
- •When performing intra-articular injections in horses, choose bupivacaine over lidocaine to minimize inflammatory response in the joint
- •Do not use 0.9% saline solution alone as an adjunct to intra-articular injections, as it triggers an inflammatory cascade
- •Monitor for signs of post-injection inflammation more carefully after lidocaine use compared to bupivacaine in joint procedures
Key Findings
- •Both lidocaine and bupivacaine induced serum and synovial fluid changes indicative of inflammation, with lidocaine causing more pronounced changes than bupivacaine
- •Bupivacaine demonstrated a safer inflammatory profile than lidocaine for intra-articular injection in horses
- •Saline solution (0.9%) also induced inflammatory reaction but with less magnitude than both local anesthetics
- •Acute phase protein concentrations in synovial fluid were measured as biomarkers of inflammation response