Guinea pigs are highly social animals that suffer profoundly when kept alone. Understanding their social needs is fundamental to good welfare.
Guinea pig welfare science is clear: these are obligate social animals for whom solitary housing constitutes a welfare failure. The Swiss law prohibiting lone guinea pig keeping is a rational legislative response to this evidence. In the UK and most countries, however, solitary guinea pigs are common. The welfare cost is real and measurable - elevated cortisol, reduced engagement with enrichment, and stereotypic behaviours in lone animals compared to paired ones. The solution is straightforward: always keep guinea pigs in at least pairs, introduce them carefully, and seek advice from knowledgeable rescuers if introduction difficulties arise. Rescue organisations can often provide pre-bonded pairs.