Guinea pigs used in laboratory research are highly social animals whose welfare is severely compromised by individual housing, and evidence supports group housing as achievable and beneficial in most research contexts.
Guinea pig welfare in laboratory settings suffers from a structural mismatch between the species social needs and the convention of individual housing. Guinea pigs are herd animals with no natural solitary existence; isolation exposes them to chronic stress that affects both welfare and potentially the quality of data generated in experiments. The argument that social housing complicates experimental design has been challenged by numerous researchers who have demonstrated compatible group housing protocols. Individual housing should be considered a welfare-compromising exception requiring specific justification rather than the default. Guinea pigs in enriched social housing show more natural behaviour, lower stress hormones, and better growth, all of which benefit research validity as well as welfare. Vitamin C deficiency, a common welfare problem in inadequately managed colonies, causes scurvy with painful joint and tissue changes that represent a preventable welfare failure.