In many animal experiments scientists and local authorities define a body-weight reduction of 20% or more as severe suffering and thereby as a potential parameter for humane endpoint decisions. In this study, we evaluated distinct animal experiments in multiple research facilities, and assessed whether 20% body-weight reduction is a valid humane endpoint criterion in rodents. In most experiments (restraint stress, distinct models for epilepsy, pancreatic resection, liver resection, caloric restrictive feeding and a mouse model for Dravet syndrome) the animals lost less than 20% of their original body weight. In a glioma model, a fast deterioration in body weight of less than 20% was observed as a reliable predictor for clinical deterioration. In contrast, after induction of chronic diabetes or acute colitis some animals lost more than 20% of their body weight without exhibiting major signs of distress. In these two animal models an exclusive application of the 20% weight loss criterion for euthanasia might therefore result in an unnecessary loss of animals. However, we also confirmed that this criterion can be a valid parameter for defining the humane endpoint in other animal models, especially when it is combined with additional criteria for evaluating distress. In conclusion, our findings strongly suggest that experiment and model specific considerations are necessary for the rational integration of the parameter 'weight loss' in severity assessment schemes and humane endpoint criteria. A flexible implementation tailored to the experiment or intervention by scientists and authorities is therefore highly recommended.

中文翻译：

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将减轻体重定义为人道的终点：一项重要的评估。

在许多动物实验中，科学家和地方当局将体重减轻20％或更多定义为严重痛苦，从而将其作为人道终点决策的潜在参数。在这项研究中，我们评估了多个研究机构中不同的动物实验，并评估了体重减轻20％是否是啮齿类动物的有效人道终点标准。在大多数实验中（约束压力，癫痫发作，胰腺切除，肝脏切除，热量限制性进食和Dravet综合征的小鼠模型的独特模型），这些动物损失的体重不到其原始体重的20％。在神经胶质瘤模型中，体重的快速恶化小于20％被观察为临床恶化的可靠预测指标。相反，在诱发慢性糖尿病或急性结肠炎后，一些动物体重减轻了20％以上，而没有出现严重的不适迹象。因此，在这两种动物模型中，仅对安乐死采用20％减重标准的动物可能会导致不必要的动物损失。但是，我们还确认，该标准可以作为在其他动物模型中定义人道终点的有效参数，尤其是当它与评估遇险的其他标准结合使用时。总之，我们的发现有力地表明，对于严重性评估方案和人道终点标准中参数“体重减轻”的合理整合，必须有实验和模型方面的特殊考虑。