I need some help on this. It is very important. I have the sweetest little lab (~50 pounds) I got from a breeder in Mississippi. She is 3. My wife and I (and a few others) can do anything to her, and all is fine. But with strangers, even after she has been around them for several days, or when she is in a strange situation, she gets nippy. She is very protective of our older (13 yo mixed breed), and will not let strangers get around him. Today the dogs ran off, and when someone tried to look at the old dog's collar, she bit him. The doggy police (extremely helpful) brought them home, and she is in quarantine. What can I do about this? Is there some training that can help? I hate to have her put down, but this is not acceptable. I have a 10 month old grand daughter she wants to rough-house with. Thanks for your suggestions.