Local anaesthetics for regional and intra‐articular analgesia in the horse
Authors: Schumacher J., Boone L.
Journal: Equine Veterinary Education
Summary
# Editorial Summary: Local Anaesthetics for Regional and Intra-articular Analgesia in the Horse Schumacher and Boone's comprehensive review synthesises recent evidence on local anaesthetic use during equine lameness examinations and surgical procedures, with particular emphasis on how drug selection and administration technique influence efficacy and safety. Current evidence indicates that mepivacaine and ropivacaine are superior to lidocaine for resolving lameness through nerve blocks, whilst the absence of cutaneous analgesia does not guarantee relief of deep pain—a distinction that has important implications for interpreting diagnostic blocks. Accurate needle placement within the neurovascular bundle sheath is critical for effectiveness, and practitioners should recognise that dose potency depends on both volume and concentration rather than either factor alone. Importantly, whilst lidocaine and bupivacaine demonstrate greater chondrocyte and synoviocyte toxicity than their alternatives, the clinical significance of single intra-articular injections remains unclear, meaning risk-benefit decisions must be made on a case-by-case basis. For those seeking enhanced potency and faster onset, sodium bicarbonate buffering offers benefit, epinephrine extends analgesia duration and intensity, but combining quick-acting with long-acting agents does not produce the desired pharmacological synergy.
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Practical Takeaways
- •Choose mepivacaine or ropivacaine over lidocaine when performing diagnostic nerve blocks to improve reliability of lameness localization
- •Monitor skin sensation response carefully during nerve blocks as absence of skin sensation does not guarantee pain relief at the lameness source
- •Consider adding epinephrine to extend duration of analgesia, but avoid mixing quick- and slow-acting agents as this does not achieve desired pharmacokinetic profile
Key Findings
- •Mepivacaine and ropivacaine are more efficacious than lidocaine for ameliorating lameness caused by pain
- •Loss of skin sensation after nerve block does not necessarily correlate with loss of pain causing lameness
- •Lidocaine and bupivacaine demonstrate greater chondrocyte and synoviocyte toxicity compared to mepivacaine or ropivacaine
- •Sodium bicarbonate increases potency and speed of onset; epinephrine prolongs and intensifies analgesic effect of local anaesthetics