Rats are highly intelligent, social animals used extensively in biomedical research, with welfare needs that are frequently inadequately met in standard laboratory housing.
Rats are among the most cognitively and socially sophisticated laboratory animals, yet their welfare is frequently compromised by housing conditions that reflect past assumptions of lesser sentience rather than current scientific understanding. Single housing causes measurable psychological harm; sparse, unstimulating environments produce chronic understimulation in animals whose natural behaviour includes complex social interaction and extensive environmental exploration. The 3Rs framework requires refinement — improving conditions within research use — and rat welfare offers some of the clearest opportunities: group housing, nesting material, shelters and human socialisation are all low-cost refinements with documented welfare benefits and no negative impact on research validity.