Introduction to other dogs
When dogs are young puppies (under 12 weeks of age), as long as the dogs are UTD on vaccinations, it is generally safe to do a simple introduction and allow the puppies to sniff each other and start playing. With older dogs, however, dog introductions must be done properly, often times slowly, in order to be successful.
Walk dogs side by side (about a leash lengths distance) in a neutral manner. Do not let dogs pull, sniff, or interact with one another at this point. Walk until dogs are not paying any attention to one another. For neutral dogs, this should only take a minute, but for excited, agitated, or reactive dogs this may take some time. Be patient, and know that for some dogs this walking may need to be done over the course of multiple sessions in order to achieve a neutral state between both dogs. Once dogs are able to be around one another and show no more than casual interest, allow the dogs to greet on leash. This must be done so properly. Leashes must be slack and dogs should never sniff nose to nose. The dogs should sniff each other’s hind end first, then move up the body if desired, but again NEVER nose to nose greeting.
The Next Step:
Once the dogs have walked and greeted appropriately on leash and all has gone smoothly, drop the leashes (assuming you are in a safely enclosed area). Be sure all toys, bones, and other items that could cause tension are removed for all initial meetings amongst new dogs. Watch the dogs interact to determine if they are a good fit as housemates and/or playmates. Look for loose body language, relaxed ears and tails, play bows, etc. These are all good signs that the dogs will get along.
B.S. Animal Science
AKC CGC Certified Evaluator, Selected Mentor Trainer for Animal Behavior College, APDT Full Member