Many laboratory animals are housed in isolation for experimental reasons, but solitary housing causes significant welfare harms in social species. The shift to social housing is a major welfare priority.
Mice, rats, rabbits, primates, and many other laboratory species are intensely social animals whose welfare suffers severely in isolation. Solitary-housed animals show higher baseline stress levels, disturbed sleep, stereotypic behaviours, and reduced cognitive function — which also confounds experimental results. The scientific case for social housing therefore aligns with the welfare case. Researchers sometimes resist social housing due to concerns about fighting, disease transmission, or confounded data from social interactions. However, these concerns can generally be managed through appropriate group composition, environmental enrichment, and monitoring. Regulatory requirements for social housing are spreading and implementation is improving.