Since classes are over for the summer and I'm in the process of finding a new house, I'm spending a lot of time staying at my parents'. That's all well and good aside from the fact that my one year old pup doesn't get along with my parents' cocker spaniel poodle mix. He's only about 20 pounds and has always been hostile towards other dogs due to the fact there was never another one in the house until now. He's never been known to do any damage but from the time I first brought my dog here way back when he was a pup, their dog has growled and barked at him. He's just a dog that doesn't like to be bothered and of course still being a puppy and full of energy, my dog is all the time trying to be right up in his face. It's to the point where if my dog is in the house, the cockapoo stays hid away in my sister's room upstairs. I would put all the blame on their dog being antisocial except for the fact that any time my dog hear's a door upstairs opening, he goes flying up the stairs and runs straight for their dog barking jumping and snapping. It's like he doesn't really bother him until he sees the other dog move. Then he's right up on top of him and a barking fit ensues between the both of them. I've dealt with it the best I could until today when he got upstairs and started it and I was using my leg to break them up and nearly sent my dog flying down the stairs. Any ideas as to what I can do? My dog has been around other dogs but never one this much smaller than him and I'm scared he may actually hurt their dog one day.