Our existing dog is 3 years old and loves to play with other dogs. Yesterday we adopted a 9 month old - both dogs are Poms. We introduced them at the shelter and they got along. When we brought the new dog home, we immediately took the whole family on a walk around the neighborhood. When we entered the house, we let our "old dog" go into the door before the new dog. Then we let the dogs run around the backyard together and they had fun playing. But then the new dog WOULD NOT leave the old dog alone. He kept wanting to play, play, play and the old dog got pissed. Our new dog isn't trained so he doesn't know commands like "Leave It" yet. How can we get him to chill out w/ the old dog a little bit so they are friends, and the old dog isn't always annoyed and running away from the new dog?