Well, consider the fact that kids can be very cruel. I can picture this poor little boy walking to class with a big smile and the other kids cry "It's Mad Dog!" and jokes about rabies and the like. So parents only consider this as a middle name. Again, kids can be so cruel. I hope I didn't offend those named this! I mean no harm.
I think this is an okay name, but I would probably only give it to a kid as a middle name, unless for some reason I really wanted the kid to get picked on.