Optimising reliability of mouse performance in behavioural testing: the major role of non-aversive handling

Kelly Gouveia,Jane L Hurst

doi:10.1038/srep44999

Abstract

Handling laboratory animals during test procedures is an important source of stress that may impair reliability of test responses. Picking up mice by the tail is aversive, stimulating stress and anxiety. Responses among anxious animals can be confounded further by neophobia towards novel test environments and avoidance of test stimuli in open areas. However, handling stress can be reduced substantially by using a handling tunnel, or cupping mice without restraint on the open hand. Here we establish whether non-aversive handling, brief prior familiarisation with the test arena and alternative stimulus placement could significantly improve performance of mice in behavioural tests. We use a simple habituation-dishabituation paradigm in which animals must discriminate between two urine stimuli in successive trials, a task that mice can easily perform. Tail handled mice showed little willingness to explore and investigate test stimuli, leading to poor test performance that was only slightly improved by prior familiarisation. By contrast, those handled by tunnel explored readily and showed robust responses to test stimuli regardless of prior familiarisation or stimulus location, though responses were more variable for cup handling. Our study shows that non-aversive tunnel handling can substantially improve mouse performance in behavioural tests compared to traditional tail handling.

Highlights

The handling of laboratory animals during testing is a widely recognised source of stress that needs to be controlled, as stress induced by handling can suppress exploratory behaviour and result in impaired test performance[4,5]
As tail handling is aversive to mice and stimulates anxiety compared to the alternative non-aversive handling methods, we hypothesized that use of non-aversive handling could significantly improve the performance of animals in behavioural tests by reducing or removing unnecessary anxiety that may interfere with attention to test stimuli and/or learning
As handling method had such a major influence on general exploratory behaviour, we investigated whether adding the level of exploratory behaviour to our model, together with handling method and stimulus location, significantly predicted habituation and dishabituation responses (Table 1b)

Summary

Handling method

General exploratory behaviour was a significant predictor of the habituation response. Many studies recommend the use of extensive prior familiarisation with repeated exposures over many days, but 10 minutes familiarisation immediately prior to testing was effective in improving initial stimulus investigation in the current study Though, this mostly influenced tail handled mice, which showed extremely low stimulus investigation across all trials without arena familiarisation (confirming responses in Experiment 1). Mice handled with a tunnel performed well, with or without prior familiarisation to the test arena They showed consistently greater exploratory behaviour than those handled by tail, which led to reliable investigation of novel urine stimuli (as expected and required by the habituation-dishabituation test). This could save valuable time during testing, as well as substantially improve the reliability of behavioural responses to test stimuli that are not confounded by handling-induced anxiety

General Discussion

Methods

Findings

Additional Information