Rabbits used in laboratory research have complex social and behavioural needs that are inadequately met by conventional single housing in small metal cages, and evidence supports pair housing as achievable in most research contexts.
Laboratory rabbits experience welfare deficits from both individual housing and environmental impoverishment. Rabbits are social animals that in natural conditions live in group burrows with complex social bonds; isolation in a single small cage is profoundly stressful. The stress response to isolation includes elevated cortisol, stereotypic bar-chewing, and abnormal postures that reflect frustration and fear. Pair housing reduces these welfare indicators substantially and is feasible across the majority of research protocols used with rabbits. The argument that social housing complicates experimental design has been largely refuted by researchers who have implemented pair housing without protocol compromise. Environmental enrichment including hiding spaces, chewing material, and elevated platforms further improves welfare without experimental cost. The regulatory gap between EU and US requirements for rabbit housing has created a situation where location determines welfare outcome for equivalent research species.