If you already have a dog, you know how wonderful they are to be part of the family. You also probably have already proven to your dog that you are the leader of the pack. All dog breeds thrive better in a pack, it's just part of their natural way of being and there must be a leader and they have to understand the hierarchy of how things work in your pack or family. However, if you decide to add another dog to the family pack, you will need to know how to introduce this new dog to everyone, especially your other dog. By introducing them slowly you will lessen the stress and any negative behavior that might be between both of them.
The first thing you need to do is to try and introduce the two of them somewhere that it is neutral. They should not be introduced in your home. You should ask a family friend or a member of your family to go on a dog walk with you. This is a great way for the two dogs to meet on their own terms and in a positive manner. All dogs love going for a walk and this gives them a way to interact without feeling like they are rivals.
After you get the two dogs home, it's probably a good idea if you keep them separated for a few nights even if they appear to be compatible. You should especially do this if there seems to be some aggression between the two of them when they get home. You can either put up a baby gate to separate them or put them in two different dog crates. Whatever you do, still make sure that they have a guarded access to one another so they can sniff and see each other without actually coming into full contact.
Once they start showing some friendly interest in each other, it's time to let them play with each other either in your yard or in the living room. Make sure that you put leashes on them so that if they start to show any signs of aggression you can easily grab the leash and correct their negative behavior by pulling them apart and then putting them in separate rooms.
After awhile you should start increasing the amount of time that they are allowed to spend time together and play. In a lot of cases, the new dog is accepted in a week or so. But don't get discouraged if that doesn't happen. It could take as long as three or four months before they are running around acting like best friends. After all, it takes a while. Do you, for instance, become instant friends with someone you meet on the first day? So why should dogs be any different?
Make sure to never feed the dogs together, this is one of the quickest ways to get a dog to become aggressive. You should also not let the new dog play with any of your other dogs favorite toys. You should get the new dog his own toys. In time they may be sharing each others toys but in the beginning it's not a very good idea to let this happen.
You are going to let both dogs know that you love them and you can do this by giving each dog some personal attention, just for them. This will boost their confidence in themselves and in the fact that you love them. You should also take time out to try and pay attention to both of them at the same time. This lets them both know that you love them both and they need to share that love with you.
Safety Note: Whatever you do, should the two of them get into a real fight, never try to step between them and stop it. Either throw a blanket on them or make some sort of loud and startling noise to get them to stop the fighting.