Laboratory animals across species have strong social needs that are frequently inadequately met, and improving social housing is one of the highest-impact welfare interventions available in research settings.
Social housing represents one of the most consistently effective and feasible welfare improvements in laboratory animal care. The evidence base is strong across species: socially housed animals show lower baseline cortisol, less stereotypic behaviour, better immune function, and more natural behaviour patterns than singly housed counterparts. Critically, social housing does not simply make animals happier - it produces better science by reducing the stress-related variables that confound research results. The resistance to social housing in some research facilities reflects unfamiliarity, space constraints, and concern about inter-animal aggression rather than evidence that isolation is preferable. Careful group formation, appropriate environmental complexity, and staff training make social housing achievable for most commonly used species.