Mirror, mirror, on the wall (2020)

Reading, P., Reading, R., Branstone, C.

Abstract

When mice are grouped together for the first time it is a novel experience filled with new sights and smells which will stress the animal too much and may cause aggression. It has been proven that mice can see a reflection of another mouse in the mirror, so by adding a mirror prior to grouping, they become accustomed to the sight of another mouse. A mirror is placed inside each cage hanging from the grid using a hook. A handful of bedding and nesting material should be swapped over daily and placed by the mirror. This should be repeated for 2-3 days. On the final day the mice should be placed together in a clean cage with no mirror. This method currently has a 78% success rate and has been used across a variety of different strains including different strain pairing. The mirror has been proven to be a vital part of the strategy as only 16% of non-mirror pairings were successful.