Environmental enrichment for laboratory animals reduces suffering, improves psychological wellbeing, and often improves research validity — yet enrichment is inconsistently provided and frequently omitted on unfounded grounds of experimental interference.
The failure to provide environmental enrichment to laboratory animals is both a welfare failure and often a scientific mistake. Animals in barren, isolated conditions are chronically stressed, and chronic stress affects virtually every physiological system studied in biomedical research. The irony that enrichment is withheld in the name of research quality, when evidence increasingly suggests it improves reproducibility, makes this a welfare failure that researchers should find self-interested reasons to correct. The 3Rs framework provides the ethical mandate; the evidence base provides the scientific justification. What is needed is regulatory enforcement and cultural change within research institutions.