Wever Kimberley E, Geessink Florentine J, Brouwer Michelle A E, Tillema Alice, Ritskes-Hoitinga Merel
1 SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE).
2 Medical Library, Radboud University Medical Center, Nijmegen, The Netherlands.
Lab Anim. 2017 Dec;51(6):583-600. doi: 10.1177/0023677217705912. Epub 2017 Apr 21.
Toe clipping and ear clipping (also ear notching or ear punching) are frequently used methods for individual identification of laboratory rodents. These procedures potentially cause severe discomfort, which can reduce animal welfare and distort experimental results. However, no systematic summary of the evidence on this topic currently exists. We conducted a systematic review of the evidence for discomfort due to toe or ear clipping in rodents. The review methodology was pre-specified in a registered review protocol. The population, intervention, control, outcome (PICO) question was: In rodents, what is the effect of toe clipping or ear clipping, compared with no clipping or sham clipping, on welfare-related outcomes? Through a systematic search in PubMed, Embase, Web of Science and grey literature, we identified seven studies on the effect of ear clipping on animal welfare, and five such studies on toe clipping. Studies were included in the review if they contained original data from an in vivo experiment in rodents, assessing the effect of toe clipping or ear clipping on a welfare-related outcome. Case studies and studies applying unsuitable co-interventions were excluded. Study quality was appraised using an extended version of SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE)'s risk of bias tool for animal studies. Study characteristics and outcome measures were highly heterogeneous, and there was an unclear or high risk of bias in all studies. We therefore present a narrative synthesis of the evidence identified. None of the studies reported a sample size calculation. Out of over 60 different outcomes, we found evidence of discomfort due to ear clipping in the form of increased respiratory volume, vocalization and blood pressure. For toe clipping, increased vocalization and decreased motor activity in pups were found, as well as long-term effects in the form of reduced grip strength and swimming ability in adults. In conclusion, there is too little evidence to reliably assess discomfort due to toe or ear clipping, and the quality of the available evidence is uncertain. Adequately powered, high-quality studies reporting reliable, relevant outcome measures are needed to accurately assess the impact of these identification techniques. Until more reliable evidence is available, any effect of toe clipping or ear clipping on animal welfare and study results cannot be confirmed or excluded.
剪趾和剪耳（也称为耳刻或耳打孔）是实验室啮齿动物个体识别常用的方法。这些操作可能会造成严重不适，进而降低动物福利并扭曲实验结果。然而，目前尚无关于该主题证据的系统总结。我们对啮齿动物因剪趾或剪耳导致不适的证据进行了系统综述。综述方法在已注册的综述方案中预先确定。人群、干预措施、对照、结局（PICO）问题为：在啮齿动物中，与不剪趾或假剪趾相比，剪趾或剪耳对与福利相关的结局有何影响？通过在PubMed、Embase、Web of Science和灰色文献中进行系统检索，我们确定了7项关于剪耳对动物福利影响的研究，以及5项关于剪趾的此类研究。如果研究包含来自啮齿动物体内实验的原始数据，评估剪趾或剪耳对与福利相关结局的影响，则纳入综述。案例研究和应用不合适的联合干预措施的研究被排除。使用实验室动物实验系统评价中心（SYRCLE）动物研究偏倚风险工具的扩展版本对研究质量进行评估。研究特征和结局指标高度异质，所有研究均存在不明确或高偏倚风险。因此，我们对所确定的证据进行了叙述性综合。没有一项研究报告样本量计算。在60多种不同结局中，我们发现有证据表明剪耳会导致不适，表现为呼吸量增加、发声和血压升高。对于剪趾，发现幼崽发声增加、运动活动减少，以及成年后握力和游泳能力下降等长期影响。总之，证据太少，无法可靠评估剪趾或剪耳引起的不适，现有证据的质量也不确定。需要开展有足够效力、高质量的研究，报告可靠、相关的结局指标，以准确评估这些识别技术的影响。在获得更可靠的证据之前，无法确定或排除剪趾或剪耳对动物福利和研究结果的任何影响。
