Anaesthesia of farmed fish: implications for welfare
Anaesthesia of farmed fish: implications for welfare
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DOI：
10.1007/s10695-011-9565-1
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发表时间：
2012-02-01
影响因子：
2.9
通讯作者：
Kiessling, Anders
中科院分区：
文献类型：
--
作者：
Zahl, Inger Hilde;Samuelsen, Ole;Kiessling, Anders
在作为养殖动物的生命周期中，有几种情况下鱼类受到处理和限制。在养殖条件下，网、称重、分类、接种疫苗、运输以及最后的屠宰是经常发生的事情。作为研究对象，鱼类也可能经历从标记、取样和小切口到侵入性程序的外科手术。在这些情况下，可能需要使用麻醉剂进行治疗，以确保鱼类的福利。本文的主要目的是回顾我们的知识的麻醉剂在养殖鱼类的影响和福利的可能影响。由于物种之间和物种内部对麻醉的反应存在很大差异，因此特别注意体重、水温和急性应激等次要因素的重要性。在这篇综述中，我们仅限于麻醉剂，如苯并咪唑，美卡因（MS-222），盐酸美咪酯，异丁香酚，2-苯氧乙醇和喹哪啶。鱼类的麻醉规程通常指的是一种单一药剂，而人类和兽医的规程则包括几种药物的组合，每种药物都有助于麻醉所需的效果。由于麻醉前的压力可能导致异常反应，因此经常使用麻醉前镇静以减少或避免压力，并且是高等脊椎动物兽医方案的组成部分。此外，用于获得全身麻醉的麻醉剂与靶向伤害感受的镇痛剂组合。因此，增加在鱼类中使用这种组合作为一个特殊的部分。麻醉剂被广泛用于避免各种农业过程中的压力。虽然有几项研究报告说，麻醉剂在减少与监禁和处理有关的压力方面是有效的，但有迹象表明，麻醉本身可能会引起压力反应，这是通过皮质醇水平升高来衡量的。据报道，MS-222在接触后立即引起高皮质醇释放率，而苯并咪唑引起双峰反应。美托咪酯对鱼的皮质醇有抑制作用，并且似乎在文献报道的药剂中诱导最低的皮质醇释放。与在处理和禁闭等严重压力源后观察到的情况相比，麻醉后释放的皮质醇量似乎很低，但在其他压力情况下可能代表额外的负荷。此外，麻醉剂可能会引起继发性不良反应，如由于呼吸停止和血液与水之间的气体和离子交换不足而引起的酸中毒和渗透压应激。总而言之，麻醉剂可以减轻压力，从而改善鱼的福利，但也可能产生不必要的副作用，降低鱼的福利，因此应始终谨慎使用。最后，在文献中报告的数据和我们自己的经验的基础上，我们建议，麻醉协议应始终在几条鱼在现行条件下进行测试，以确保足够的麻醉深度。这一建议适用于是否使用单一的代理或代理的组合，虽然它似乎包括代理的组合协议提供了更广泛的safety margin.The止痛效果目前使用的代理，尽管他们的证明局部效果，目前正在辩论的代理管理通过吸入鱼类，而不是在目标位置的局部。因此，我们建议，所有需要全身麻醉的手术方案都应辅以在组织创伤部位给予具有镇痛作用的药物。
During their life cycle as farmed animals, there are several situations in which fish are subjected to handling and confinement. Netting, weighing, sorting, vaccination, transport and, at the end, slaughter are frequent events under farming conditions. As research subjects, fish may also undergo surgical procedures that range from tagging, sampling and small incisions to invasive procedures. In these situations, treatment with anaesthetic agents may be necessary in order to ensure the welfare of the fish. The main objective of this paper is to review our knowledge of the effects of anaesthetic agents in farmed fish and their possible implications for welfare. As wide variations in response to anaesthesia have been observed both between and within species, special attention has been paid to the importance of secondary factors such as body weight, water temperature and acute stress. In this review, we have limited ourselves to the anaesthetic agents such as benzocaine, metacaine (MS-222), metomidate hydrochloride, isoeugenol, 2-phenoxyethanol and quinaldine. Anaesthetic protocols of fish usually refer to one single agent, whereas protocols of human and veterinary medicine cover combinations of several drugs, each contributing to the effects needed in the anaesthesia. As stress prior to anaesthesia may result in abnormal reactions, pre-anaesthetic sedation is regularly used in order to reduce or avoid stress and is an integral part of the veterinary protocols of higher vertebrates. Furthermore, the anaesthetic agents that are used in order to obtain general anaesthesia are combined with analgesic agents that target nociception. The increased use of such combinations in fish is therefore included as a special section. Anaesthetic agents are widely used to avoid stress during various farming procedures. While several studies report that anaesthetics are effective in reducing the stress associated with confinement and handling, there are indications that anaesthesia may in itself induce a stress response, measured by elevated levels of cortisol. MS-222 has been reported to elicit high cortisol release rates immediately following exposure, while benzocaine causes a bimodal response. Metomidate has an inhibitory effect on cortisol in fish and seems to induce the lowest release of cortisol of the agents reported in the literature. Compared to what is observed following severe stressors such as handling and confinement, the amount of cortisol released in response to anaesthesia appears to be low but may represent an extra load under otherwise stressful circumstances. Furthermore, anaesthetics may cause secondary adverse reactions such as acidosis and osmotic stress due to respiratory arrest and insufficient exchange of gas and ions between the blood and the water. All in all, anaesthetics may reduce stress and thereby improve welfare but can also have unwanted side effects that reduce the welfare of the fish and should therefore always be used with caution. Finally, on the basis of the data reported in the literature and our own experience, we recommend that anaesthetic protocols should always be tested on a few fish under prevailing conditions in order to ensure an adequate depth of anaesthesia. This recommendation applies whether a single agent or a combination of agents is used, although it appears that protocols comprising combinations of agents provide wider safety margins.The analgesic effects of currently used agents, in spite of their proven local effects, are currently being debated as the agents are administrated to fish via inhalation rather than locally at the target site. We therefore recommend that all protocols of procedures requiring general anaesthesia should be complemented by administration of agents with analgesic effect at the site of tissue trauma.