Preferences of mice, Mus musculus, for different types of running wheel

Mice are increasingly used in research. In particular, their wheel running is often used as a measure of activity, and as a marker of phase of circadi an rhythms. Learning about the preferences of mice for different types of w heel may improve their welfare and suggest ways of increasing activity leve ls. Mice, Mus musculus, were given a choice between different types of runn ing wheel by putting them in cages equipped with two wheels. Strong prefere nces were shown for wheels with a plastic mesh flooring, rather than the st andard metal rods only. The mesh was even preferred over a solid base, alth ough this effect was not seen in mice that had been given access only to wh eels with the solid base immediately prior to the choice test. Small diamet er wheels, sometimes sold as mouse wheels, were preferred less than standar d-sized wheels with rods. The results suggest that types of running wheel o ften used in laboratories can be improved by considering the animals' prefe rences. The types of wheel tested here are easy to maintain and entail litt le additional cost, while increasing the mouse's interest in running and ex ercise.