Enrichment for laboratory mice has been extensively studied, and the evidence shows clear welfare benefits with minimal impact on experimental validity.
Laboratory mice are among the most commonly used research animals, with hundreds of millions used annually worldwide. For decades, barren caging was standard practice based on the assumption that enrichment would introduce unwanted experimental variability. Evidence has overturned this assumption - enriched mice are not more variable but are healthier, less stressed, and produce more reliable data. Providing enrichment for laboratory mice is now both ethically required and scientifically beneficial. The welfare obligation to these animals is clear, and the excuses for barren housing have largely been dismantled.