Laboratory rats are among the most cognitively complex animals used in research, and their intelligence creates both welfare obligations and research opportunities.
The rich cognitive and emotional life of rats means that laboratory conditions significantly affect their welfare and experimental validity. Social isolation, barren caging, and chronic mild stress protocols cause genuine suffering in animals capable of complex emotional experience. The 3Rs framework mandates refinement of rat housing to include social housing, environmental enrichment, and positive human-animal interaction. These welfare improvements also reduce experimental variability by controlling stress-induced physiological changes.