I have a black Pitbull, his name is Momo..
He weighs 75-80 lbs and is almost 2 years old. He is the BIGGEST baby you will ever meet, but he is so protective of my wife its not even funny. I love it.
When Im around he is fine. But when Im not. He will bark at every little noise. When she walks him without me he will growl at older guys that are walking toward them. I dont know if he would actually do anything. But, he doesnt do it when Im around.