Mice like their cages warm, research finds

Mice raised in cages may relieve stress with behaviors more often associated with mice living in the wild, Purdue University in Indiana reports.

For researchers, this finding may mean they have to give up some control and allow mice to express themselves more naturally to ensure more reliable research data, the West Lafayette, Ind., university said in a news release.

Laboratory mice live in sterile environments controlled by humans, which can create stress for the animals since they don’t have much control, said Joseph Garner, assistant professor of animal sciences and lead researcher.

The perception of (the lab mouse’s) ability to control stress has a bigger impact on the animal than does the stress itself, he said. Chronic, uncontrollable stress changes animals, making them different than normal. This ultimately makes them less valid research subjects.

The scientists placed mouse cages in water baths set to different temperatures, connected the cages with tunnels and waited for the mice to beat feet to their favorite locale. The most popular choice was the warmest cage kept at 86 degrees Fahrenheit, he said.

They actually select different temperatures at different times of day and for different behaviors, Garner said. So, while they preferred the warmer temperatures most of the time, it may not be possible to select a single preferred temperature for all mice.

The research was reported online in Applied Animal Behavior Science.