Department of Comparative Medicine, Stanford University, Stanford, California;, Email:
Department of Comparative Medicine, Stanford University, Stanford, California; Department of Psychiatry and Behavioral Sciences (by courtesy), Stanford University, Stanford, California.
Comp Med. 2022 Jun 1;72(3):204-209. doi: 10.30802/AALAS-CM-22-000050. Epub 2022 Jun 14.
The exponential rise of the zebrafish () as a model organism in biomedical research has far outstripped our un- derstanding of basic husbandry and welfare for this species. As a case in point, here we investigate the efficacy and welfare impact of different euthanasia methods for zebrafish. Not only is a humane death central to welfare and the 3Rs, but stress during euthanasia can change scientific outcomes. However, the most frequently used methods of euthanasia have multiple shortcomings with regard to animal welfare and human safety. In this study, we propose the use of propofol for immersion euthanasia of adult zebrafish. Propofol has been known to rapidly induce anesthesia in many species, including zebrafish, but its efficacy as a euthanasia agent for zebrafish has not fully been explored. In this study, adult zebrafish were euthanized by immersion on one of 5 different preparations: ice bath, 250 ppm MS222, 600 ppm lidocaine hydrochloride, 100 ppm propofol, or 150 ppm propofol for 20 or 30 min. Display of aversive behaviors, time to loss of righting reflex, time to cessation of opercular movement, and time to recovery after transfer to clean tank water were assessed and recorded. Propofol at both concentrations induced loss of righting reflex and loss of opercular movement more quickly than did MS222 or lidocaine hydrochloride and caused no display of aversive behaviors as seen with ice bath or lidocaine exposure. However, fish exposed to propofol at either concentration for 20 min sometimes recovered, whereas a 30-min exposure was sufficient for euthanasia of all fish tested. These findings suggest that exposure to propofol for a duration of at least 30 min quickly and effectively euthanizes adult zebrafish without compromising end-of-life welfare.
斑马鱼（）作为一种生物医学研究模型，其数量呈指数级增长，而我们对该物种的基本饲养和福利的了解却远远落后。这里，我们以不同的安乐死方法为例，研究其对斑马鱼的效果和福利影响。人道处死不仅是福利和 3R 的核心，而且安乐死过程中的压力会改变科学结果。然而，最常使用的安乐死方法在动物福利和人类安全方面存在多个缺点。在这项研究中，我们提出使用丙泊酚对成年斑马鱼进行浸浴安乐死。丙泊酚已被证明能迅速使许多物种（包括斑马鱼）麻醉，但它作为斑马鱼安乐死剂的效果尚未得到充分探索。在这项研究中，成年斑马鱼被浸入以下 5 种不同制剂之一中进行安乐死：冰浴、250ppm 的 MS222、600ppm 的盐酸利多卡因、100ppm 的丙泊酚或 150ppm 的丙泊酚，浸泡 20 或 30 分钟。评估并记录出现厌恶行为、失去翻正反射的时间、停止鳃盖运动的时间以及转移到清洁水箱水后恢复的时间。与 MS222 或盐酸利多卡因相比，两种浓度的丙泊酚都能更快地诱导失去翻正反射和停止鳃盖运动，并且不会像冰浴或盐酸利多卡因暴露那样出现厌恶行为。然而，在 20 分钟内暴露于任一种浓度的丙泊酚的鱼有时会恢复，但 30 分钟的暴露足以使所有测试的鱼安乐死。这些发现表明，暴露于丙泊酚至少 30 分钟可以快速有效地使成年斑马鱼安乐死，而不会影响其生命末期的福利。
