Guinea pigs are highly social animals that suffer significantly when kept alone, with group housing being an essential welfare requirement for the species.
Guinea pig social welfare is one of the most well-established welfare requirements in small pet species. Solitary guinea pigs show stereotypies, elevated stress hormones, and reduced exploratory behaviour compared to group-housed animals. The species' need for conspecific companionship is so well established that Swiss law mandates pair housing. Providing appropriate social housing requires attention to bonding procedures, space requirements, and sex management, but the welfare benefit is substantial and the management challenges are tractable.