Introducing a pet to your home is exciting and everyone is usually looking forward to the new arrival. The most important step for the new pet is his introduction to the members of the household, especially the resident pets. With assurance that everyone will have a place in the new "pack", dogs usually enjoy having a companion with whom to share their family. Cats will accept dogs into the territory as long as they still have sole rights to at least one room they enjoy.

Introduce a new dog to your resident dog away from home. Have a friend bring the new dog to the park and take your dog there. Ignore the new dog yourself but allow the dogs to meet at their own pace. Allow the dogs time to get comfortable with each other. Play ball with your dog and allow the new dog to join in gradually. Be sure to appear less interested in the dog than your friend is. 

Once both dogs are relaxed, walk home with your dog while your friend follows with the new dog. Walk into your house together. Continue ignoring the new dog. Offer both dogs a treat, resident dog first. If your dog growls at the new dog, ignore it. If the new dog growls at your dog and your dog ignores it, you should too. If either dog snaps teeth, say "No". This reminds BOTH dogs that you expect them to get along.

Do not move your dog's bed or toys to make room for the new dog and don't feed the dogs closely to each other. Whenever you are away from home the dogs should be separated. The new dog should have a crate even if your old dog does not. Each dog should have separate time to play and build a relationship with you as his leader as well as time to share you.

If other members of the family are paying special attention to the new dog, be sensitive to both dogs' behavior at these times. The best way to handle any tension or aggression between the dogs is to distract them by opening the door to a fenced yard or by calling them to another room. Be sure not to appear to give your dog a reward for poor behavior toward the newcomer by allowing them to play outside every time they appear to fight--but unrelated distractions from the DOG's point of view work wonders.

If you are introducing a dog to a resident cat, you will need to set up a barrier so that there are parts of the house the dog cannot enter, to which your cat has access. Try to block off your cat's favorite part of the house, your bedroom or a sunny family room, with a baby gate. If the new dog is able to jump the gate, raise it from the ground so that your cat can run under but the dog cannot. If the dog can still get through, stack two gates or install a cat door and keep the human door to the area closed. This will give your cat a secure area so that he can build a relationship with the dog over time. You should target train your new dog to better handle him in the presence of the cat (see Basic Lesson).