5. Introduce them to other pets on neutral ground
If you have other dogs that have a tendency to become territorial, introduce them to the puppy for the first time at a local park rather than at home. This will help your existing pets to accept the new member without feeling too threatened. If you are adopting a puppy from a shelter, then you can ask to bring your existing pets to the shelter first to ensure that there are no serious problems. Most shelters have nearby exercise grounds or you can take all the dogs to a nearby park.