Stereotypic behaviors in laboratory mice are primarily caused by barren, inadequate housing, and preventing their development through environmental design is more effective than attempting to reduce established stereotypies.
Stereotypy prevention demonstrates a fundamental principle in welfare science: early intervention is dramatically more effective than later correction. Mice that develop stereotypies during the sensitive juvenile period maintain them even when later moved to enriched environments — the behavioral patterns become neurologically entrenched through habit formation. This means that the welfare decision made at weaning — whether to provide adequate nesting material and shelter — determines the welfare trajectory of the animal for its entire laboratory life. Providing proper enrichment from birth costs virtually nothing relative to the welfare improvement it delivers. The scientific case is equally compelling: stereotypic mice show increased behavioral variability and altered stress physiology that confounds experimental results. Prevention is simultaneously the welfare-optimal and science-optimal approach.