Guinea pigs are obligatorily social animals that suffer psychological distress when kept alone, making correct companionship one of the most important welfare requirements for this widely kept companion species.
Guinea pig welfare fundamentally requires the company of conspecifics. These are animals that have never lived solitarily in their evolutionary history and have no capacity to adapt to isolation. A guinea pig kept alone is a guinea pig in chronic psychological distress regardless of how attentive the owner is, because human interaction cannot replace the constant social contact of a companion. Welfare-conscious guinea pig keeping begins before acquisition by planning for a pair or bonded group, and continues through understanding that each animal requires its own veterinary care even when keeping multiple animals increases costs.