Guinea pigs are highly social animals whose welfare is severely compromised by solitary housing — yet millions of pet guinea pigs are kept alone, often in small hutches without adequate companionship or space.
Guinea pigs are prey animals that evolved in social groups — their stress-response systems are calibrated for the presence of companions. Solitary housing triggers chronic low-grade stress that suppresses immune function, reduces social behavior, and impairs psychological wellbeing. Solitary guinea pigs in small hutches — the most common housing configuration sold to families — fail on two of the most critical welfare dimensions simultaneously. Switzerland and Germany have recognized this through legislation; most countries have not.