When they’re all played out, have both animals a moderate distance away from each other so that they can see each other but still remain calm. Give them treats for remaining calm.
For dogs, have them both on leash, with one person per dog. Do your best to keep the leashes slack, so you don’t transfer any extra stress into the situation. If in a fenced area, the leashes can be trailing on the ground.
Make sure neither pet gets too anxious, fearful, or aggressive during the introduction to ensure that the experience is a good one. Look for stress signs including yawns, tightly closed mouths, shake offs as though the dog is wet, tail tucked or head averted. If either dog appears anxious, walk them away and redirect them using simple commands and rewards. You can use a game of tug or fetch to help redirect them, and be sure to have them slightly hungry so that the treats are truly a motivator.
Slowly approach with the resident dog, stopping every couple of feet to ask a simple command and reward both animals frequently. If they seem comfortable with this, walk them close enough to allow them to just sniff each other’s noses. If one of the dogs is young or very under-socialized, you can step on their leash, leaving it long enough to keep their four paws on the ground but not long enough to let them jump into the other dog’s face, which is often considered rude behaviour by mature dogs. Lead them away after just two to three seconds and engage with them individually, rewarding them for their good behaviour.
You can repeat this again, gradually leaving them together for longer periods before walking them away each time. Don’t get greedy! Break off the session while things are going well, so that they’re happy to get together later. Before taking them inside, walk them together side by side for a little bit, as being near but not staring at each other is great practice for building tolerance for proximity.
Take a break and let both pets settle down before inside introductions. If at any time things escalate and the dogs begin to growl, snap, or act aggressively, separate them. Stress hormones take 15 minutes to start to subside and will reactivate more quickly once they’ve been triggered, so wait at least an hour before trying again.
Mealtime and high-value resources are common triggers of unwanted competitive and guarding behaviours. Animals should be fully separated at meal times, ideally in different rooms to prevent any stress, but at least behind a barrier. When trying to introduce high-value items like bones, be sure to do so at a time when the animals are tired and full, so that they’re not too excited about getting them. Bones should not be left unattended initially, as they can trigger guarding or hoarding behaviour.
Laps and proximity to you are often even more highly valued than treats! Be sure to tire out your pets before looking to settle in, with one on either side of you receiving calming pets. Avoid having either directly on your lap if they’re on the furniture, which is more likely to trigger a response. If either growls, stop petting and if it continues, either move off the furniture or move the dogs away from you. If either dog growls intensely or snaps, move them to behind a gate.
You want to teach both pets that the highest likelihood of their receiving lots of positive physical attention from you is when the other pet is present, and this is true across species – cats, birds, lizards, etc.
Lucinda Glenny, MSc. Animal Behaviour, HBSc. Psychology