How successful you are in introducing your new puppy to the resident dog depends on a couple of variables. First, your resident dog has to have a history of getting along with other dogs. If your resident dog has picked fights with other dogs, or tends to become aggressive around strange dogs, you may not be successful in bringing a new puppy into the home.
Remove all toys, bowls or objects that your dog may see has his own possessions. This will reduce the chance that a resource guarding problem will arise as a result of your dog attempting to protect his belongings. In time, you can put these items back once you see how your dog will react to another dog playing with them.
Ask a friend to assist. It is helpful to have two people for the introduction. With both dogs on a leash, allow sniffing and distract either with praise, treats or toys if you see any tension. The absolute best way to do this is to take the dogs for a short walk together. This is called parallel walking and is an excellent way for dogs of any age to get used to each other and bond. Doing this outside creates a neutral territory. Your dog is not meeting the new dog on his own territory, but in a neutral place.
Allow the dogs to be dogs. Your puppy will probably want to jump up at the older dog’s face and lick his muzzle. This is normal, submissive puppy behavior. Your dog may snap or growl. This looks scary but it is also normal and his way of teaching the puppy manners. Do not intervene unless you see actual aggression. Warning signs are fine, but if it escalates to aggression, correct your dog immediately with a loud and stern “NO!”
Be open to letting your new puppy learn manners from your well-adjusted older dog. She will learn not to bother him while sleeping and not to take his food and toys away. Sometimes the corrections will make her carry on like she is being killed but watch closely. Most likely she will get over it within 30 seconds and will continue to follow your older dog around. She is learning.
Sometimes an adult dog will not properly correct a puppy, and the puppy can become bold and obnoxious. If this happens, have the pup trail a lightweight leash in your presence and correct and distract if she is being a real brat with the older dog. Remember to praise her when she is being good, too.
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How to Introduce Your Puppy to the Older Resident Dog