Dogs are social creatures.  When you added your dog to the family, your dog established his place within the hierarchy of your family. He may be on top, but hopefully he knows his place is below all the humans!  When you bring in your 2nd dog, the dog will be working through this hierarchy once again.  Depending on the temperament of the 2nd dog he may challenge all or some of the humans for their spot, so be warned!  There is going to be at some point some tension in the house with your new dog.

Choose A Neutral Location

Introduce the dogs in a location that is not part of either dog’s territory. Each dog should have his own handler. With both dogs on leash, take them to an area, such as a park, with which neither dog has been before.

Use Positive Reinforcement

You want both dogs to expect “good things” from their meeting. Depending on the dogs reaction to each other, you may need to hold these meetings for a few times. Let the dogs sniff each other and as they do, talk to them in a happy, friendly tone of voice, “Good Boy, Good Girl”.

Do not allow the dogs to investigate and sniff each other for a prolonged time. This can escalate to an aggressive response from one or both dogs. After a short time, get both dogs’ attention, and give each dog a tidbit of a treat in return for obeying a simple command such as “sit.”

Take the dogs for a walk and let them sniff and investigate each other at intervals. Continue with the “happy talk”, food rewards, and simple commands.

Taking the Dogs Home

When the dogs seem to be tolerating each other’s presence without fearful or aggressive responses, and the investigative greeting behaviors have tapered off, you can take the dogs home. Whether you choose to take them in the same or different vehicles will depend on their size, how well they ride in the car, how trouble-free the initial introduction has been, and how many dogs are involved. If you have more than one dog in your household, it may be best to introduce the resident dogs to the new dog one at a time. Multiple resident dogs may “gang up” on the newcomer.

At Home

Whenever more than one dog lives in a household, the dogs will establish a hierarchy. This social hierarchy is determined by the outcomes of interactions between the dogs. Owners cannot choose which dog they want to be on top. When a new dog is brought into the family, the hierarchy is upset because the newcomer’s place is unclear.

It is difficult to predict which dog will ultimately be on dog. Individual personality traits as well as breed characteristics are important factors. Initially, the resident dog is likely to appear on top, but this may change rapidly.  And that is OK

Dogs usually establish their hierarchies through a series of interactions involving ritualized behaviors that include body postures and vocalizations, that do not cause injury. One dog may “stand over” another by placing her paws on the shoulders of the other dog, or by draping her neck across his shoulders. However, because of past experiences, inadequate socialization, or genetic temperament tendencies, some dogs may instead, with very little warning, escalates into aggression. If this occurs, you may need to seek the assistance of a certified animal behaviorist.

You need to support whatever hierarchy the dogs establish for themselves. Do not undermine the natural hierarchy by attempting to treat the dogs equally or scolding the dog when he asserts his status. Dogs can and should be allowed to take toys away from more subordinate dogs, to push in and receive attention and petting from the owner, to control favorite sleeping places, toys, and other valuable (from the dog’s point of view) resources. Support the hierarchy by allowing this to occur. This can be difficult for owners to do if the resident dog becomes the subordinate dog in the hierarchy.

Keep the resident dogs’ routine as much the same as possible by keeping feeding, exercise, play, sleeping times, and locations the same as before the new dog arrived. You can also give each dog some time alone with you. 

Introducing Puppies to Adult Dogs

Puppies usually pester adult dogs unmercifully. Before the age of four months, puppies may not recognize subtle body postures from adult dogs, which are signals they have had enough. Well socialized, adult dogs with good temperaments, can set limits with puppies with a growl or snarl. These behaviors should be allowed, even if the puppy over-reacts and “screams bloody murder!” Adults, which are not well socialized, or who have a history of fighting with or challenging other dogs, may attempt to set limits with more aggressive behaviors, such as biting, which can harm the puppy. For this reason, new puppies should not be left alone with an adult dog until you are confident the puppy is not in any danger. Be sure to give an adult dog some quiet time away from the puppy and some individual attention.

If Problems Develop

If the introduction of a new dog to your household does not go smoothly, do not allow the conflicts to continue. Punishing one or both dogs is NOT the answer, and is likely to make the problem worse. Talk to a certified animal behaviorist for information about behavior modification.