Take it Slow
When bringing a new dog home, take it slow. Separate dogs using baby gates or crates so they can spend time neutralizing by seeing and smelling each other. When using crates to integrate, place them in the same room, but spaced apart. Position them parallel to each other and gradually close the distance between the crates over the course of days or weeks. Cover the back half of the crates allowing the dogs to share space but still retreat to privacy. Over the course of the first few days, rotate dogs, taking turns with one in the crate and one out.
Only have them out together for short time periods - always supervised. Remember, the new dog has to settle in with EVERYTHING so it’s a lot to take in and learn. The existing dog must make a big adjustment as well, so be understanding.
Acclimating on a Walk
Walk the dogs together with one handler per dog.
Begin in a single file line eventually moving to side by side with the handlers between the dogs.
As the dogs settle, close the gap and switch the dogs one at a time to the inside.
Stagger into a single file to allow each dog to sniff the other’s rear while continuing to walk forward.
Avoid face to face greets while on leash.
See this guide for full step-by-step instructions.
Allow the dogs to bond
It's wise to limit human affection towards dogs at first, including your existing dog(s). Doing this allows the dogs to bond with each other, without starting a competition for human attention. Otherwise, jealousy will arise along with all those problems.
Don't treat the new dog like a stepchild; you must be fair to both. Also be aware that your original dog may become a brat at times, challenging this new situation, and he/she will need to be told "no." Rules should be the same for both dogs, whether the rules are new or well-established.
Let the dogs establish their own relationship at their own pace. Don't be upset if they do not play or snuggle together from day one. There is no need to encourage them to do so. Friendships take time and you can't force it.
Mealtime
At mealtime, feed dogs separately, one in the crate, one outside, OR put the leashes on both dogs. Even the most mellow, finicky eaters can turn back to wild animals over protecting their food! Food guarding is a normal instinct for a dog, but you will want to avoid any and all potential incidents, so separate them. Over time you may be able to figure out what works best for your pack at feeding time but take it slow.
Toys and bones
Please do not give toys or bones in the beginning as they can quickly become a resource to fight over. In foster, we recommend kongs or benebones. Do not attempt to take toys or bones directly from the dog. Teaching “drop it” can be useful but will take time. If you need to remove an item from your dog, offer a trade or use a leash. Alternatively, you can use a water spray bottle to create space between the object and the dog so you can claim it. Keep your eye on the dog and make sure the dog yields the object to you before reaching for the object with your hand. As time goes by, you will get to know the dynamic between the dogs and may have toys out again if you desire.
Reminders
Take the entire process slow, nice and easy: rules & boundaries first, allow the dogs to bond at their own pace and remove objects that can lead to arguments, and supervise the dogs at all times.
For more information on introducing dogs, visit: Blue Man Dog