Ahaaa, I can bet the shock collar did the exact opposite to what you were hoping for. Thats what makes them so dangerous. The dog blamed the pain he experienced on the other people and dogs. No wonder he hates them so much.

No doubt he is trying to drive the other people and dogs away for the reasons I described above. If it was sheer excitement, he wouldn't attack other dogs when he managed to get loose. A dogs size has no bearing on whether they are afraid or not. I've had a tiny yorkshire terrier try attacking our Jess, a border collie...it regretted it. She didn't hurt it but she pinned it to the ground. It thought twice after that.