Implementing strategies to reduce singly housed male mice.

There are different husbandry situations that lead to social isolation of male mice. Besides legal considerations, single housing has a negative impact on behavioural and molecular studies. We have implemented two strategies, the 'companion mouse' and just-weaned male grouping, to reduce the number of male mice housed singly in our facility. We have achieved a progressive reduction (42% in three years) without an increase in aggression.