Quote Originally Posted by Nadie View Post
Well, we take her to the dog park at least four times a week, nearly every day in the summer, and she's usually very good and gentile while playing with other dogs. She never barks at them, and she's good at matching their aggressiveness. I've seen her hold her own against a giant Mastiff and then turn around and start chasing a puppy with extreme sensitivity. That is why it confuses me so much that she would have an aggression problem. There doesn't seem to be any warning signs that I have noticed. She's not protective of me :P. Once there was food involved, but the other three times there wasn't.
She knows sit, down, stay, come and a few tricks like weave and holding treats on her nose. We have been to obedience school as well.

Do you know of any behavior specialists or where to find one? Would her Vet be helpful?

Oh, also, three of the times the dogs were female old black labs. the fourth was just a random little dog who wasn't black at all, but it's curious that the first three were all very similar.
Sure, where are you located? You vet probably would not be very helpful, as they are trained to look for medical, not behavioral issues. Did the incidents happen close together, or are they sporadic? When she gets into it with another dog, can you distract her or call her to you successfully? Sounds like a coincidence 3 were older black Labs, after all - they are the most popular breed in America! Knowing where you are would help us (Pet Talk people) find a good behaviorist for you!