Local anaesthetics or their combination with morphine and/or magnesium sulphate are toxic for equine chondrocytes and synoviocytes in vitro.
Authors: Rubio-Martínez L M, Rioja E, Castro Martins M, Wipawee S, Clegg P, Peffers M J
Journal: BMC veterinary research
Summary
# Editorial Summary: Local anaesthetics and equine joint toxicity Whilst intra-articular local anaesthetics are routinely used for diagnostic and therapeutic purposes in equine practice, their safety profile in equine tissues remains incompletely understood. Rubio-Martínez and colleagues exposed cultured equine chondrocytes and synoviocytes to clinically relevant concentrations of mepivacaine and bupivacaine, both alone and combined with morphine and/or magnesium sulphate, measuring cell viability and inflammatory cytokine gene expression (IL-1β, IL-6, TNF-α). Both local anaesthetics significantly reduced cell viability and upregulated pro-inflammatory cytokine expression; notably, combining either agent with morphine or magnesium sulphate amplified these cytotoxic effects, whereas morphine and magnesium sulphate alone demonstrated no harmful impact on articular tissues. These findings carry important implications for intra-articular injection protocols: clinicians should minimise local anaesthetic exposure time during diagnostic blocks and carefully reconsider whether adjunctive agents offer genuine clinical benefit when they potentiate chondrocyte and synovial toxicity. Given that even single exposures produced measurable cellular damage, future research into less toxic local anaesthetic alternatives or protective strategies may warrant investigation, particularly for horses requiring repeated intra-articular procedures.
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Practical Takeaways
- •Local anaesthetic choice and dose matter for intra-articular injections—minimise exposure time and consider alternatives to mepivacaine and bupivacaine where possible
- •Adding morphine or magnesium sulphate to local anaesthetics does not protect articular tissues and may worsen toxicity; reconsider multi-drug combinations for joint blocks
- •While this is in vitro data, it suggests caution with repeated intra-articular local anaesthetic use and supports thorough joint lavage after diagnostic/therapeutic procedures
Key Findings
- •Mepivacaine and bupivacaine alone significantly reduced chondrocyte and synoviocyte cell viability and increased pro-inflammatory cytokine gene expression (IL-1β, IL-6, TNF-α)
- •Morphine alone and magnesium sulphate alone did not alter cell viability or inflammatory cytokine expression
- •Combination of local anaesthetics with morphine and/or magnesium sulphate enhanced cytotoxic effects compared to local anaesthetic alone
- •Single short exposure to local anaesthetics demonstrated toxicity to equine articular tissues in vitro