Local mepivacaine before castration of horses under medetomidine isoflurane balanced anaesthesia is effective to reduce perioperative nociception and cytokine release.
Equine Vet J. 2018 Apr 16;:
Authors: Abass M, Picek S, Carzòn JFG, Kühnle C, Zaghlou A, Bettschart-Wolfensberger R
BACKGROUND: In horses castration with primary intention healing is usually performed under balanced inhalation anaesthesia. To optimise analgesia, the use of local anaesthesia was tested.
OBJECTIVES: To investigate the effect of local mepivacaine before castration with first intention healing under balanced medetomidine-isoflurane anaesthesia and flunixin meglumine, morphine analgesia on perioperative cytokine levels and pain in horses.
STUDY DESIGN: Prospective blinded clinical study.
METHODS: Twenty stallions were randomly assigned to control or mepivacaine groups. Flunixin meglumine was administered before sedation with medetomidine and followed by ketamine/diazepam i.v. Anaesthesia was maintained with isoflurane and 3.5 μg/kg/h medetomidine. Mepivacaine horses were given mepivacaine 2% (3.5 mL SC, 1 mL/100kg intrafunicularly, 2 mL/100kg intratesticularly). on each side 2 minutes before incision. For recovery horses were given 2 μg/kg medetomidine i.v. and 0.1 mg/kg morphine i.m. and oral phenylbutazone (0.02 mg/kg q12h) for postoperative analgesia. One hour before premedication and 4, 8 and 24 hours post incision, pain was scored with three different pain scales (Equine Utrecht University Scale for Facial Assessment of Pain, Horse Grimace Scale, Equine Utrecht University Scale for Composite Pain Assessment) and plasma cytokines (interleukin-6 and tumour necrosis factor alpha) were measured. Data were analysed using repeated measures ANOVA, linear regression and unpaired t-test, significance level p≤0.05.
RESULTS: Horses in both groups showed a significant increase in pain scores and cytokines compared to baseline. Postoperatively the mepivacaine group exhibited significantly lower pain scores and cytokine levels. Mean heart rate during anaesthesia was significantly lower in the mepivacaine group compared to control group (28.8 ± 1 and 33.2 ± 1.7 respectively). Otherwise there were no differences between the groups.
MAIN LIMITATION: The decision to provide additional analgesia was based on the attending surgeon's assessment rather than a standardised rescue analgesia plan based on pain scores. The study was only conducted for 24 hours post-castration and complications were not recorded.
CONCLUSION: Local mepivacaine before castration with primary wound closure improved anaesthesia quality, attenuated postoperative increases in cytokines and reduced postoperative pain despite balanced anaesthesia with multimodal analgesia in control horses. This article is protected by copyright. All rights reserved.
PMID: 29660154 [PubMed - as supplied by publisher]