The long droopy ears of a bloodhound did not evolve to improve their hearing, but to stir the air and waft scent past their keen noses. Chihuahuas are the only breed of dog to be born with an incomplete skull. Like human babies, chihuahuas have moleras, or a soft spot in their skulls, that fill in with age. Statistics show that raccoons have the largest number of rabies cases in a single species. The Afghan Hound is scientifically proven to be the dumbest dog in the world. Unvaccinated dogs are the number one transmitters of the rabies virus worldwide.