Impact of Refinements to Handling and Restraint Methods in Mice

SIMPLE SUMMARY: For laboratory mice, handling methods used for routine husbandry and procedures can cause stress, particularly if tail handling methods are used. We first sought to investigate if there were any measurable impacts of different handling methods when tested in a controlled real-world study. Animals were handled at our breeding site using different methods, and their impacts on handling post-transport to the research site were analysed by animal care staff. We found a clear effect of handling method on technician scores relating to overt signs of stress and how easy they were to handle. Based on this study, the institution implemented a refined mouse handling policy. However, one barrier to the use of non-tail handling methods has been arguments that tail handling is necessary for restraint in mice. With a relatively minor adaptation to the conventional restraint method, we have been able to combine cupping with physical restraint for procedures avoiding any use of the tail. Here we provide data showing that our modified restraint method is associated with reduced signs of aversion in the mice. Together, our findings support the implementation of refined handling policies for mice, and this can include handling for both husbandry and restraint for procedures. ABSTRACT: There is increasing evidence that, compared to non-aversive handling methods (i.e., tunnel and cupping), tail handling has a negative impact on mouse welfare. Despite this evidence, there are still research organisations that continue to use tail handling. Here, we investigated handling for routine husbandry by three different methods: tail, cupping and tube in a relevant real-world scenario involving mice bred off-site. After transfer to the destination unit, mice were assessed for overt behaviours associated with anxiety and fear. Mice that experienced tail handling were less easy to handle, were more responsive to the box opening, and scored lower in a hand approach test. One barrier to non-tail handling methods is the current practice of restraining mice by the tail for procedures. We therefore next assessed whether a modified method for restraint that takes the animal from cupping to restraint without the use of the tail was associated with better welfare. This refined restraint method reduced overt signs of distress although we did not find any differences in corticosterone levels or anxiety-related behaviours. These findings suggest that avoiding tail handling throughout the animal’s laboratory experience, including during restraint, benefits their welfare.