Guinea pigs are obligate social animals whose welfare is severely compromised by solitary housing — they require companionship of their own species as a fundamental welfare need.
Guinea pig social welfare is one of the clearest examples of a fundamental behavioral need in companion animals. Guinea pigs evolved in social groups and have maintained complex social structures over millions of years — their stress response systems are calibrated for social living. A solitary guinea pig is not simply an animal who lacks a friend; it is an animal experiencing chronic welfare compromise from the absence of a fundamental need. The welfare imperative is clear: guinea pigs must be housed with compatible companions of their own species. Switzerland's legal requirement reflects this scientific consensus.