Individual or singly-housing laboratory rats is common in many animal facilities, but has an adverse impact on the welfare of this social species. It has previously been shown that a small proportion of individually housed mice (∼5%) engage in pathological overgrooming behaviour, but this has not been assessed in rats. We performed an observational study to determine the prevalence of overgrooming-related self-injury and whether providing nesting material enrichment throughout an animal's life would affect the prevalence or severity of overgrooming-related self-injury. Due to protocol differences between projects in our behavioural neuroscience lab, unenriched rats received a nylabone and a shelter (n = 167), while baseline-enriched rats received a nylabone, shelter and shredded paper nesting material throughout experiments (n = 238). Unenriched rats received nesting material enrichment after the onset of overgrooming-related self-injury. Over 18 months, rats were monitored by their experimenters on a daily basis (5-7 days/week over 2-3 months/project) and any cases of overgrooming-related self-injury were recorded. Replicating the findings of previous studies in mice, we observed 20 cases of overgrooming-related self-injury (∼5%) with no difference in prevalence between rats on the basis of supplier, cage position, experimental procedure (behavioural only or involving surgical procedures), reinforcer (ethanol or sugar) or level of baseline-enrichment. While there was no difference in onset severity between rats that were unenriched at baseline and baseline-enriched rats, baseline-enriched rats had lower self-injury severity scores at one-, two- and four-week follow-ups. These results suggest that nesting material enrichment provided throughout an animal's life may reduce overgrooming-related self-injury.

中文翻译：

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筑巢材料的富集减少了单独饲养大鼠中与过度修饰相关的自我伤害的严重性。

在许多动物设施中，单独或单居的实验大鼠都很常见，但是对这种社会物种的福利有不利影响。以前已经证明，只有小部分的单独饲养的小鼠（约5％）会进行病理性的过度修饰行为，但这尚未在大鼠中进行评估。我们进行了一项观察性研究，以确定过度修饰相关的自我伤害的患病率，以及在整个动物的生命中提供丰富的筑巢材料是否会影响过度修饰相关的自我伤害的患病率或严重性。由于我们行为神经科学实验室的项目之间的协议差异，未浓缩的大鼠在整个实验过程中都接受了尼龙袋和遮盖物（n = 167），而基线丰富的大鼠在整个实验中都使用了尼龙膏，遮盖物和切碎的纸巢材料（n = 238）。未丰满的大鼠在过度修饰相关的自残发作后接受了筑巢物质的富集。在超过18个月的时间内，实验人员每天对大鼠进行监控（在每个项目2-3个月内，每周进行5-7天/周，每天进行监测），并记录与过度修饰相关的自我伤害的情况。复制先前小鼠的研究结果，我们观察到20例与修饰过度有关的自体伤害（〜5％），根据供应商，笼子位置，实验程序（仅行为或涉及手术程序），大鼠之间的患病率没有差异），增强剂（乙醇或糖）或基线富集水平。基线时未充盈的大鼠和基线期充盈的大鼠之间发作严重程度无差异，但基线充盈的大鼠在1、2和4周的随访中自我损伤严重性评分较低。