Guinea pigs are popular small pets, especially for children, but their welfare needs — particularly around sociality, diet, and space — are frequently misunderstood, leading to preventable suffering in millions of animals.
Guinea pig welfare failures are extremely common despite — or perhaps because of — their reputation as easy starter pets. Social isolation causes depression and chronic stress in animals evolutionarily adapted to group living. Vitamin C deficiency from inadequate fresh vegetable provision causes painful scurvy. Dental disease from inadequate hay intake causes chronic mouth pain. Commercial cages marketed for guinea pigs are almost invariably too small for proper movement. These problems are entirely preventable with correct information: pairs minimum, large enclosures, unlimited hay, and fresh vitamin-C-rich vegetables daily. The Swiss legal requirement for companion animals is an appropriate welfare baseline that other countries should consider.