by Lucinda Glenny, MSc. Animal, Behaviour, HBSc. Psych., CPDT-KA, owner and lead trainer of Canine Campus (

Our pets are important family members, and new animals need to be introduced into the home with care. Dogs have the mental maturity of a two- to four-year-old child, so it’s a bit like the sibling rivalry when a new baby is brought home. While there may be a positive experience of excitement, there will likely be a reaction of displacement and, to some degree, jealousy.

Resident animals get into a routine and may see the home as their personal territory. When you bring home a new animal or have visitors with pets, your resident pet’s first instinct may be to run away or to fight off the “intruder.”

Adding a new pet to your household can be stressful for your current pet and may lead to stress-related sickness or behavioural issues. It is important to slowly introduce resident pets to any new animals – don’t just throw them together and hope for the best!

Choosing an animal that will fit in well with your resident pet will help immensely. Understanding the health, activity level, and personality of your current pet and the new pet you are thinking of bringing home will help you anticipate – and preempt – any problems. For example, a slower, older dog may not get along with a high-energy puppy. While the two can eventually coexist happily, you’ll need strategies that safely keep the pets apart initially, until the pup is more mature.

Before bringing your new pet home

Your current pet must be healthy enough to handle the stress of the new family member. Undiagnosed pain can reduce tolerance levels for interactions and result in aggression. Prior to committing to the new pet, take your current pets to the vet. Sick animals may be unable to adapt to changes in their environment because they are not at their best. They may also pose a risk to puppies or kittens, which are more susceptible to germs due to their young age.

Set up a temporary area for the new pet using gates, exercise pens, or doors. This area should have all the essentials they need. Allowing your new pet full access to your house might overwhelm them. Setting up a small space will allow them to get used to one area at a time.

It is a good idea to have different belongings for both pets. Sharing can be difficult, especially at the beginning. Giving each pet their own toys, bowls, bed, and crate (and scratching posts and litter boxes for cats) will reduce anxiety.

Making the introduction

The car ride home is the beginning of training your new pet. It is important to provide a carrier, crate, or safety harness for them in the car so they are more likely to remain calm. Resist the urge to bring along your resident pet for the pick-up; it is already a highly charged and stressful situation, and the confines of a car is not a good place to start the introductions.

Familiar smells can help to calm animals. Bringing your new pet home with a blanket or bedding that they have been using will help lower their anxiety. You can also get something from them when you go for the initial visit to bring home; put the new pet’s blanket in the bed of the current pet, so that they get the idea that something different is coming.

Be aware of the timing for the introduction: immediately after a long car ride to their new home is not ideal. Allow the new animal to explore their separate area before bringing them to a neutral area to greet the resident pet.

 Before the initial introduction, spend time with each animal individually, with the goal of tiring them out. This will help prevent either animal from being reactive.

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.

Resource guarding

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