My dog is a very sweet dog. I however am perplexed. When he sees some dogs he gets very aggressive and attacks them, whereas other dogs he wont. He turns from sweet to attack mode. He did it today at the dog park. I was concerned about taking him but he did well. Then when we were leaving I was talking to this couple and the gentleman was actually petting my dog. Then another guy came by with his dog and he attacked it. Not only that but when I tried to get him to stop he ran and attacked the dog again. The lady had to catch him by his holster for me. I was so embarrassed and always am when he does that. Funny thing is, at Petsmart where I take him quite often, all the staff love him and says how he gives them hugs and likes to play in day camp so much. He only get cranky there if another dog comes up to one of the staff and he is hugging them. Please any advice this is driving me crazy!