Guinea pigs get lonely, so it is highly recommended by experts for people to own the pets in pairs. In fact, in Switzerland, it is actually illegal to own a single guinea pig. Since guinea pigs are by nature very social animals, they often become withdrawn when on their own due to not having other guinea pigs around to communicate, play, and groom together as they would in the wild. Two baby guinea pigs of the same gender typically have the highest likelihood for successful cohabitation, followed by a baby guinea pig and older guinea pig of the same gender. Guinea pigs may have distinctive personality traits that can clash if two older animals are introduced.
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