Guinea pigs are highly social animals for whom solitary keeping causes chronic welfare impairment. Understanding their social needs enables owners to provide appropriate companionship that dramatically improves quality of life.
Solitary guinea pig keeping is a welfare failure that Swiss legislation recognized a decade ago and that welfare science clearly supports as causing harm. Guinea pigs kept alone cannot express the social vocalizations and behaviors that define their social nature — they have no recipient for the purring, rumblestrutting, and social grooming that form core components of guinea pig behavioral life. The chronic stress of social isolation affects immune function, behavior, and lifespan. The solution is straightforward: guinea pigs should be kept in pairs or small groups. The additional cost of keeping two rather than one is modest compared to the welfare benefit. Pet retailers who sell single guinea pigs without welfare guidance to prevent single-animal keeping are contributing to a preventable welfare problem.