Pet behaviorist and author Steve Duno answers this week's question.

Question: What is the best way to introduce a dog to a new home that already has at least one other dog in residence?

Answer: It depends on a number of factors, the most important being the resident dog. If the established dog is gregarious, well-adjusted and well trained, it can be an easy matter.

I've introduced new puppies and adult rescues right into my home without problems. Generally this works for me because my resident dogs are confident, friendly and obedient, with a real sense of how to communicate the home rules to the new kid on the block.

I usually will mainstream the new dog right in, let the dogs work it out themselves, stepping in only if there is untenable aggression.

A sign of serious aggression would be any altercation that lasts for more than a few seconds, or one that results in the actual wounding of one or both dogs. Nips and/or growling are common; blood is not. If this happens, separate the dogs, and seek out professional help.

Then I include the newbie right into the routine, albeit with more restrictions regarding sleeping and eating areas (both must occur in a crate for the first few weeks).

I also need those first few weeks to establish the new dog's housetraining, which, even if adequate in its old environment, needs to be readjusted to the new home.

Within a month or two, the new dog is a happy, functioning member of my pack.

Question: What do you recommend for clients?

Answer: I usually recommend that, after finding a well adjusted, friendly dog at a shelter or from a breeder, they first introduce the new dog to the resident dog off the home property, if at all possible.

Home is the resident dog's castle, and territorial guarding can often adversely color the initial meeting. Getting them together on neutral turf is always the better bet.

I usually advise them to walk the new dog and the resident dog down a street, with purpose, one person to a dog, before even letting them greet -- a controlled, all-business kind of walk, a block down then back.

Then, if they can find a fenced-in area, I recommend the dogs be allowed off their leashes to meet and greet, run around, posture, work it out.

Being off leash is crucial, as the restriction of the leash can often incite worry during the critical greeting ritual.

The initial walk simply sends the statement that the owners are in charge of the choreography and the social dynamic, and that, once they have displayed the ability to walk sanely for a few minutes, they'll be rewarded with a romping introduction.

Most of the time this off-leash greeting works, provided both dogs are reasonably sociable. If the dogs tolerate each other, they then can be taken to the home, where the new dog is shown the layout on leash, and training can immediately begin.

Question: How does an owner teach a new dog the rules of the house?

Answer: It is crucial that the new dog be taught what the rules and routines are as soon as possible, and that it understands it must earn total autonomy and trust from you and the resident dog.

Crating for eating and sleeping are good ideas for the new dog, at least for a few weeks, to prevent food aggression and to ensure good housetraining.

Once the dogs settle in, these restrictions can be eased. But the new dog must be trained and must be taught to respect the established dog's rank in the home. Over time they will work out a hierarchical arrangement, but in the beginning, the owner must maintain order and civility. Some nipping and growling is to be expected; let it happen, and step in only if it erupts into overt aggression.

Usually it will work itself out as the new dog learns the etiquette of the home. During the first few months, both dogs should be required to do "down-stays" within sight of each other, in different areas of the home, under supervision. This helps teach them that it's not always play time, and that they need to be able to act civilly when together.

The "down-stay" anchors them to a spot, teaches focus and helps build confidence and thoughtfulness. The new dog will have to learn this behavior. And if the old dog doesn't know it, it will have to do the same.

Question: How is introducing a puppy into the mix different from introducing an adult dog?

Answer: Introducing a puppy into the home of an adult dog is much easier than bringing in an older rescue; the established dog will most likely teach the puppy the rules, while tolerating a certain level of juvenile behavior.

But the puppy must start its training right away, and learn the ropes and routines. Luckily, if the resident dog is well behaved, the puppy will model after the old timer and learn to fit in quickly. That is one of the benefits of getting a new dog while the older dog is still around; they pass on their knowledge and habits to the rookie.

If the resident dog has a history of dog aggression, it's best to work on that first, before thinking about introducing a new dog into the fray. A new dog isn't the answer to the old dog's failings, or to the owner's.

Steve Duno

Pet behaviorist and author Steve Duno has authored 19 books and scores of magazine and Web articles. He has covered a wide variety of subjects on both dogs and cats, including basic training, aggression, environmental enrichment, behavior modification, breed profiling, trick training, and pet health care. Formerly a teacher in New York City and Los Angeles, he now lives in Seattle with his family and an ever-changing assortment of rescued pets.

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