Hi all. I have an English Bull Terrier - 2 years old. He's very friendly, obeys commands, we've been attending a dog trainer since he was a pup. He loves people and is very playful, plays with other dogs. The thing that bothers me happened recently - we were on a walk and he was playing with another dog in the park ( a Samoyed, I prefer him playing with bigger breeds, because he's heavy ) when a woman came with her Jack Russel Terrier and he started running through the playing dogs' legs and barking - I called my dog and leashed him - we were leaving when the Samoyed followed us, because he wanted to play again, and the Jack Russel ran after the Samoyed and again barked and ran - than the thing happened - my dog caught the Jack Russel by the skin of the neck, I didn't expect my dog to do that, he didn't bark or growl or show any signs of attack. I immediately told him to release and pulled him back, the Jack Russel was very frightened but wasn't injured at all. The reaction of my dog after I pulled him back was whimpering and whining and wagging tail as if he was playing. I don't know why he did that, he had never fought or attacked before and that didn't look like a typical attack. Does someone have a clue why that could have happened and why the reaction after that was wagging tail?