Guinea pigs are highly social animals whose welfare is fundamentally compromised when kept alone, a practice still common despite clear evidence of the harm it causes.
A lone guinea pig is a suffering guinea pig. These intensely social animals require same-species companionship for psychological wellbeing in ways that human interaction cannot substitute. Switzerland recognized this legally; many other countries have not yet followed. Beyond socialization, guinea pigs require a hay-based diet, vitamin C supplementation, and a spacious enclosure far larger than commonly sold starter cages provide.