Guinea pigs are highly social animals that suffer significant welfare costs when kept alone, making group housing an ethical requirement for responsible ownership.
Social housing for guinea pigs is not simply preferable but essential for their welfare. Solitary confinement in guinea pigs causes measurable physiological and behavioural stress equivalent to a chronic welfare compromise. Yet many guinea pigs continue to be sold and kept alone, partly because owners are unaware of the strength of this social need and partly because housing space for pairs seems to require more investment. In reality, a properly sized enclosure for two guinea pigs provides better welfare than a smaller enclosure for one, and the companionship benefit is profound.