Guinea pigs are popular companion animals but are frequently kept in conditions that fail to meet their fundamental social, spatial, and dietary needs. Understanding their biology is essential for good welfare.
Guinea pig welfare suffers primarily from mismatched expectations: purchased as "easy starter pets" or children's companions, they are often kept in conditions — small cages, solitary housing, poor diet — that cause chronic welfare deficits. The social welfare need is fundamental: guinea pigs housed alone show elevated cortisol, increased stereotypic behaviour, and reduced exploration compared to socially housed conspecifics. The vitamin C requirement is a welfare-critical dietary fact that is not widely known; owners who feed dry pellets without fresh vegetables routinely produce animals with subclinical or clinical scurvy. Dental disease is a hidden welfare problem because guinea pigs mask pain effectively — weight loss may be the first owner-visible sign, by which point significant molar pathology has often developed. Improving guinea pig welfare requires better pet shop and breeder advice at point of sale, more accurate minimum cage size standards, and greater public awareness that these animals have complex, specific needs equivalent in seriousness to those of cats and dogs.