Guinea pigs are highly social prey animals that should always be kept with companions. Solitary housing is a major welfare failure — recognising and meeting their species-specific needs is essential for responsible ownership.
Guinea pig welfare failures are widespread due to underestimation of their space, social and dietary needs. Solitary guinea pigs develop anxious behavioural profiles with reduced exploration, increased vigilance and vocalisation reflecting distress. Small commercial cages prevent natural movement patterns — guinea pigs in appropriate spaces popcorn (joyful bouncing and running) that is entirely absent in confined animals. Dietary welfare is critical: guinea pigs cannot synthesise vitamin C (like humans) and require fresh vegetables daily. Dental disease from insufficient hay is common and causes chronic pain that is difficult to detect. Rabbit/guinea pig cohousing — historically recommended — is now known to cause welfare problems as rabbits can injure guinea pigs and species communication is incompatible.