So you want to adopt another dog. How do you handle the first one?
It is natural for the first dog to try and protect his territory but it’s great that you want to find a solution so you can bring them together!
Walk your dogs together
Dogs, when they get company, need to learn that they are together and that you are the boss. The simplest, easiest way to reinforce that is by walking them on a leash. Walk them on either side of you, keep the leash short so they can’t go across you and lunge. Walk them as many times in a day and for as long as you can. It will reinforce that they are together and that you are the leader.
Keep them together in the house
Do not separate them in your presence in different rooms. You need to discourage the first dog from attacking the second. As a rule, we would never allow any dog to bring on an attack. Keep a rolled-up newspaper handy and use it on the dog that attacks first. Dogs tend to announce it much before they pounce- their body becomes tense, there’s low growling and a baring of teeth. Talk to the dog at this stage firmly and tell her not to do it. If she pounces, use the rolled-up newspaper immediately and separate them.
You need to reinforce the behavior that they can’t go at each other. Dogs need discipline and they need to learn to listen to what you want.It’s not difficult to bring about this change and it does not take more than a couple of days.