Guinea pigs are highly social animals that suffer when kept alone, and the welfare case for social housing is now firmly established in veterinary and welfare guidance.
Guinea pig social welfare is one of the clearest examples in companion animal keeping where the welfare science is unambiguous: keeping guinea pigs alone causes chronic suffering through social deprivation. The species has evolved complex social communication and relies on conspecific contact for security and emotional regulation. Solitary guinea pigs show higher stress responses to novelty, vocalise more in response to separation, and have elevated corticosterone levels indicating chronic stress. Switzerland's legal requirement for social housing reflects the strength of this evidence. Welfare guidance in the UK from the RSPCA, PDSA, and RWAF all strongly recommends social housing as a fundamental welfare requirement.