Shy pups and adult dogs are more likely to bite because they are scared, and that can become a huge issue. Some pups may act confident until they're in a crate and you reach inside to get them out--and the puppy attacks! What's going on with that?
Cage fear is one sign of fear aggression, and there are others. Here's an article that explains why fear aggression happens, what signs to watch for, and what you can do. Learn more here.