Laboratory rats are highly intelligent, social rodents whose welfare in research settings has improved substantially through social housing, environmental enrichment, and refined procedures.
Laboratory rat welfare reflects a species with exceptional cognitive and social complexity that requires accordingly complex environments for adequate welfare. Social housing with compatible cage-mates provides companionship, play, and allogrooming that are fundamental behavioral needs for rats. Environmental enrichment that includes shelters, nesting material, and manipulable objects engages rats' strong exploratory and play behavior. The empathy research - rats freeing other rats from restraint and sharing food with hungry companions - has welfare implications beyond the experimental findings: these results reveal animals with social and emotional lives more complex than their historical treatment in research reflected. The Rat Grimace Scale allows pain to be objectively assessed and managed, completing a welfare framework that addresses both positive and negative welfare states.