dogs weird behavior

Question
hello i have a 2 yr old female pitbull named Hennessey. and although she is spoiled she is also well trained. she knows her basic commands as well as some minor tricks.unfortunately she has developed a bad habit which im sure your familiar with...she has over the years become aggressive with other dogs. now this is surprising because we have 2 other dogs at home as well as 2 cats and she isnt the alpha of any of them. i cant take her out to dog parks even though she is well trained because i fear she might fight.also all of a sudden she's developed a nipping habit.not with the family but with friends or neighbors.she will allow them to pet her briefly before turning and attempting to nip/bite.none of the other dogs are like that and i cant possibly see where this has come from.i tried to let people offer her a treat and then pet her or i've held her head away but nothing seems to work can you give me any advice on these 2 behavior issues any comment would be appreciated thank you.

Answer
Amanda, your dog's behavior is not abnormal at all, for her breed. They have been bred for decades to be aggressive towards other dogs and small animals. It's in their nature. Sometimes, this aggressive nature doesn't come out until the dog is an adult, and it sounds like your dog is 'coming into her own,' so to speak. Please know that I am not saying all of this to frighten you. I've no doubt your dog is a wonderful family pet, as most pit bulls are (I have a pit mix myself). However, I would suggest that you find a trainer locally that is experienced with the bully breeds and dog-to-dog aggression that can help you learn how to control and correct her behavior now, before it gets worse. I would recommend that you NOT leave her alone with your other dogs and cats, because if something triggers her instincts, you could come home to some seriously injured or dead pets.

As for the nipping, it needs to be corrected as well. It could be a sign that she is trying to assert dominance, or it could just be excitement. Regardless, I would have her on a leash and training collar whenever people want to pet her, and if she tries to nip at them, you should correct her with a verbal "NO" followed by a leash pop. Again, the trainer should be able to help with this, too.