Lizarraga I, Chambers J P
Department of Pathobiology, Ross University School of Veterinary Medicine, P.O. Box 334, Basseterre, St. Kitts, West Indies.
N Z Vet J. 2012 Mar;60(2):87-94. doi: 10.1080/00480169.2011.642772.
Awareness of pain and its effects is increasing within the veterinary profession, but pain management in food animals has been neglected. Sheep seldom receive analgesics despite various conditions, husbandry practice and experimental procedures being known to be painful, e.g. footrot, mastitis, vaginal prolapse, castration, vasectomy, penis deviation, and laparoscopy. The evidence supporting use of analgesic drugs in this species is reviewed here. Opioid agonists are of dubious efficacy and are short acting. α₂-agonists such as xylazine are good, short-lived analgesics, but induce hypoxaemia. Non-steroidal anti-inflammatory drugs (NSAID) such as ketoprofen provide long-lasting analgesia, but not as marked as that from α₂-agonists; they should be more widely used for inflammatory pain. Local anaesthetics reliably block pain signals, but may also induce motor blockade. Balanced analgesia using more than one class of drug, such as an α₂ agonist (e.g. medetomidine) and N-methyl-D-aspartate antagonist (e.g. ketamine), with the combination selected for the circumstances, probably provides the best analgesia for severe pain. It should be noted that there are no approved analgesic drugs for use in sheep and therefore the use of such drugs in this species has to be off-label. This information may be useful to veterinary practitioners, biomedical researchers, and regulators in animal welfare to develop rational analgesic regimens which ultimately may improve the health and welfare of sheep in both farming and experimental conditions.
兽医行业对疼痛及其影响的认识正在提高,但食用动物的疼痛管理却一直被忽视。尽管已知各种病症、饲养操作和实验程序会引起疼痛,如腐蹄病、乳腺炎、阴道脱垂、去势、输精管切除术、阴茎弯曲和腹腔镜检查,但绵羊很少接受镇痛药治疗。本文综述了支持在该物种中使用镇痛药的证据。阿片类激动剂疗效存疑且作用时间短。α₂激动剂如赛拉嗪是良好的短效镇痛药,但会导致低氧血症。非甾体抗炎药(NSAID)如酮洛芬可提供持久镇痛,但效果不如α₂激动剂显著;它们应更广泛地用于炎性疼痛。局部麻醉药能可靠地阻断疼痛信号,但也可能导致运动阻滞。使用一类以上药物进行平衡镇痛,如α₂激动剂(如美托咪定)和N-甲基-D-天冬氨酸拮抗剂(如氯胺酮),根据具体情况选择组合,可能为严重疼痛提供最佳镇痛效果。需要注意的是,目前尚无批准用于绵羊的镇痛药,因此在该物种中使用此类药物属于超说明书用药。这些信息可能对兽医从业者、生物医学研究人员以及动物福利监管机构制定合理的镇痛方案有用,最终可能改善养殖和实验条件下绵羊的健康和福利。
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