How to successfully introduce two dogs?

Introduce on neutral territory. It’s best to let dogs become familiar with each other on neutral territory: outdoors. Each dog should be walked separately on a leash, and each walker should have a bag of high-value treats or food broken into small pieces. At first, walk the dogs at a distance where they can see each other but are not too provoked by each other’s presence. If the dogs are not showing any negative behaviors, reward them with treats just for seeing each other. Pay attention to each dog’s body language. Watch carefully for body postures that indicate a defensive or wary response, including hair standing up on the dog's back, teeth baring, growling, a stiff-legged gait or a prolonged stare. If you see such postures, either when the dogs are at a distance or near each other, immediately and calmly interrupt the interaction by interesting the dog in something else. If the dogs seem relaxed and comfortable, you can shorten the distance between them. Let the dogs determine the pace of the introduction. The most important thing is to take this introduction slowly. Do not force the dogs to interact. Once the dogs are able to view each other at a close proximity, allow one dog to walk behind the other, and then switch. If the dogs remain comfortable, allow them to walk side by side. Finally, let the dogs interact under close supervision. If one or both dogs show any signs of stress or agitation, proceed more slowly with the introduction.

When you're introducing two dogs to each other, first impressions matter. How the dogs interact in their first few encounters can set the tone for their entire relationship, so follow these steps to set their relationship up for success. Start on neutral territory where you have plenty of space, like a park, open field, or quiet street. Start on opposite sides of your space walking the same direction. When one dog looks at the other one, they get a treat. Keep walking until they are no longer focused on each other. Repeat your walk and reward method moving about 3-5 feet closer. As long as the dogs continue to pay more attention to you and less attention to the other dog, continue walking. If the dogs become too focused on each other, add more distance until they can successfully walk, take treats, and ignore each other. Slowly decrease the distance until the two humans can walk next to each other with the dogs to the far right and left of them, and can move forward without obsessing over the other dog. Once you’re consistently walking well, allow the dogs to circle and sniff each other for a few seconds then lead them away. Repeat this several times. Any time the dogs’ bodies go still, lead them away and take a break. Once you have several meetings where the dogs’ bodies appear relaxed, the next step is to try the two dogs loose in a fenced area so they can move around as they wish. Do outdoor introductions before bringing the dogs into the house together. Leave the leashes on so you can control both dogs if needed. Be sure to remove any bones, toys, and food bowls that your resident dog might feel the need to protect from the new dog. Keep the dogs separated while you are gone until they are comfortable with each other under a variety of circumstances. When you are home, supervise their interactions and give them breaks from each other by crating one at a time or taking them for separate walks. If an altercation occurs, separate the dogs for a few days to give them a break from each other.