I have two Goldens, brother and sister. Ginger, the female, extremely well behaved. Diego, the male, has a few problems. He used to pull, but I have trained him loose leash walking, except when he sees dogs on walks. There are some times when he shows aggression towards big dogs. I let him meet, usually it's face to face, and he will bark like crazy if he isn't friendly. Anybody know why? I've read things where dogs do not show dominance, so is this a form of fear or something? He wasn't socialized as a puppy, I was really little when we got them. So I understand why he is this way. Other big dogs he's fine with, others not so much. Like today, these two dogs came our way and he walked right up to them and started barking constantly. It was very deep and really got me nervous. I'm a teenager so when I'm in these situations I forget to look at his body language and such. Any advice? I'm going to go to a professional trainer's house sometime soon for a private lesson.