I think there are statistics, but I don't know where they are, so take this with a load of salt. Most dog bites are done by small dogs. I think it's something like a Napoleon syndrome. And the reason why they bite is loyalty, and their desire to protect their owners.
I've dealt with all kinds of animals - I'm thinking Stilly has too, and you pretty much have to realize it's THEIR world. The dogs, gerbils, raccoons, cats, or whomever, can't. Some of us - I ain't naming names ;) - are, for whatever reason, more at home in certain animals' worlds. I'm good with cats. I think I'm better with dogs. And horses. There are people who get upset being expected to adapt to another creature's world, but that never does any good. As someone famous (possibly, but at least, quoted a lot) once said, "it is what it is."