Reducing Mouse Anxiety during Handling: Effect of Experience with Handling Tunnels

Kelly Gouveia,Jane L Hurst,Eric M Mintz

doi:10.1371/journal.pone.0066401

Abstract

Handling stress is a well-recognised source of variation in animal studies that can also compromise the welfare of research animals. To reduce background variation and maximise welfare, methods that minimise handling stress should be developed and used wherever possible. Recent evidence has shown that handling mice by a familiar tunnel that is present in their home cage can minimise anxiety compared with standard tail handling. As yet, it is unclear whether a tunnel is required in each home cage to improve response to handling. We investigated the influence of prior experience with home tunnels among two common strains of laboratory mice: ICR(CD-1) and C57BL/6. We compared willingness to approach the handler and anxiety in an elevated plus maze test among mice picked up by the tail, by a home cage tunnel or by an external tunnel shared between cages. Willingness to interact with the handler was much greater for mice handled by a tunnel, even when this was unfamiliar, compared to mice picked up by the tail. Once habituated to handling, C57BL/6 mice were most interactive towards a familiar home tunnel, whereas the ICR strain showed strong interaction with all tunnel handling regardless of any experience of a home cage tunnel. Mice handled by a home cage or external tunnel showed less anxiety in an elevated plus maze than those picked up by the tail. This study shows that using a tunnel for routine handling reduces anxiety among mice compared to tail handling regardless of prior familiarity with tunnels. However, as home cage tunnels can further improve response to handling in some mice, we recommend that mice are handled with a tunnel provided in their home cage where possible as a simple practical method to minimise handling stress.

Highlights

Handling stress is often pointed out as a potential source of unexplained variation within and between animal studies
A major complication of variability in the responses of research animals is that it implies an increase in the numbers required for experiments [5,6], while important responses may be overshadowed by handlinginduced stress and missed
While this study showed a striking difference in response to handling by these different methods, it is unclear whether the reduced stress response to tunnel handling depends on mice being familiar with the handling tunnel

Summary

Introduction

Handling stress is often pointed out as a potential source of unexplained variation within and between animal studies. This is because handling stress is known to influence both the behaviour and physiology of animals [1,2,3,4]. The need for research on how to overcome confounding effects of handling in experimental studies has been underemphasized This is important because it is impractical to standardise exactly when, how frequently or for how long animals are handled for routine maintenance and experimental manipulations between studies; and yet stressful experiences may have a major impact on the status and responses of experimental animals. In addition to the impact on research outcomes, the influence of routine handling on the expression of anxiety behaviour raises concern for the welfare of many millions of mice that are kept within animal facilities

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