Stage one: quarantine before any meeting
A new guinea pig should live separately for a settling period before introductions, in its own cage with its own equipment, tended after your existing pig each day. This protects your resident from anything the newcomer might be carrying and gives the new pig time to learn your household's sounds, smells and routine without the added pressure of a stranger. Use those days to confirm the newcomer is eating well, producing normal droppings and breathing quietly, and to let it get used to your hands delivering food.
Stage two: the neutral-ground meeting
Introductions belong on ground neither pig considers home: a large pen on an unfamiliar floor, set with scattered hay piles, vegetables spread widely, two water bottles and hideys with two exits so nobody can be trapped. Place both pigs in together and supervise continuously. A bigger space for a longer session works better than a small box for ten minutes, because guinea pig introductions are mostly negotiation — rumbling, teeth chattering, nose-to-nose stand-offs, chasing and mounting — and the pair need time and room to finish the conversation.
Knowing when to watch and when to step in
Most of what you will see and hear is normal sorting-out, and pigs who break off to eat or wander apart between bouts are progressing well. Step in calmly, sliding a towel or board between them rather than grabbing, only for biting that draws blood, a locked rolling fight, or a pig cornered and screaming with no escape. If a first meeting ends in blood, separate the pair, let them live side by side in divided housing where they can see and smell each other, and try again after a break; some pairs — particularly adult boars — need a slower road, and a few simply will not pair.
Choosing the newcomer with the meeting in mind
The introduction starts at selection. A younger pig is often accepted more readily by an established adult than another adult is, and a neutered boar with a sow, or two sows, tend to be calmer combinations than two adult boars meeting for the first time. If the newcomer comes from a rescue, ask what it has lived with before; a pig who has already lived happily in company usually settles into a new partnership faster. Whatever the pairing, bring the newcomer home to its quarantine cage first — introductions made on arrival day stack travel stress on top of social stress.
Stage three: living together
After a long session of eating, resting and moving calmly together, move the pair into their permanent cage scrubbed clean, rearranged, and furnished with two of everything — bowls, bottles, hideys — to remove both territorial scent and competition. Watch feeding times closely across the first week, and weigh both pigs, since a subordinate pig can quietly lose access to food. A newcomer or resident with a bite wound, or either pig going off its food, should be seen by a vet. Logging the quarantine days and introduction sessions in KinsLe's Care Teams gives the new pig's whole settling-in a shared record, so whoever is on duty knows exactly which stage the introduction has reached.