Local mepivacaine before castration of horses under medetomidine isoflurane balanced anaesthesia is effective to reduce perioperative nociception and cytokine release.
Authors: Abass M, Picek S, Garzón J F G, Kühnle C, Zaghlou A, Bettschart-Wolfensberger R
Journal: Equine veterinary journal
Summary
# Editorial Summary Castration remains one of the most commonly performed equine surgical procedures, yet optimising perioperative pain management remains clinically relevant even when using balanced anaesthesia with systemic analgesics. This prospective, blinded study compared 20 stallions undergoing castration with primary intention healing, randomly assigned to receive either standard multimodal analgesia (medetomidine, isoflurane, flunixin meglumine and morphine) or the same protocol supplemented with local mepivacaine infiltration at spermatic cord, testicular and subcutaneous levels. The mepivacaine group demonstrated significantly lower pain scores across all three assessment scales at 4, 8 and 24 hours post-operatively, whilst also showing attenuated inflammatory responses—measured as reduced interleukin-6 and tumour necrosis factor alpha levels—compared to controls, with mean intraoperative heart rates notably lower (28.8 versus 33.2 bpm). These findings suggest that integrating local anaesthesia into routine castration protocols provides meaningful additional analgesia despite comprehensive systemic pain management, supporting its adoption as standard practice to minimise nociceptive signalling and the associated inflammatory cascade. Future work addressing longer-term recovery outcomes and standardised rescue analgesia protocols would strengthen the clinical evidence base for this approach.
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Practical Takeaways
- •Adding local mepivacaine injections (subcutaneous, intrafunicular, and intratesticularly) to routine castration anaesthesia significantly reduces post-operative pain and stress markers in horses, improving welfare outcomes
- •Local anaesthetic blocks allow reduced inhalation anaesthetic requirements and lower heart rates, potentially improving cardiovascular stability during castration procedures
- •Implementing local mepivacaine as standard practice for equine castration provides superior analgesia compared to systemic multimodal analgesia alone, with no reported adverse effects
Key Findings
- •Local mepivacaine administration significantly reduced post-operative pain scores across all three pain assessment scales compared to control group
- •Mepivacaine group showed significantly lower plasma cytokine levels (IL-6 and TNF-α) post-operatively despite balanced anaesthesia in controls
- •Mean heart rate during anaesthesia was significantly lower in mepivacaine group (28.8 ± 1 bpm) versus control (33.2 ± 1.7 bpm)
- •Local anesthetic supplementation improved overall anaesthesia quality and attenuated surgical stress response in horses undergoing castration with primary intention healing