Laboratory mice are the most widely used research animals, with over 100 million used globally annually. Simple, low-cost enrichment significantly improves their welfare without compromising research validity.
The welfare of laboratory mice matters despite their small size and large numbers. Each mouse experiences its own life — its own fear, curiosity, and social relationships. The standard barren cage of many research facilities frustrates the natural behaviors that these animals are strongly motivated to perform: burrowing, nesting, hiding, foraging, and social interaction. Nesting material added to cages costs pennies per animal and significantly improves welfare through reduced stress, better thermoregulation, and natural behavior expression. The 3Rs framework (Replace, Reduce, Refine) applied rigorously to mouse research requires active investment in refinement through enrichment, not passive acceptance of historical husbandry standards that were designed for convenience rather than welfare.