big sad dog Magnet

Generally speaking, canine aggressiveness is much more about nurture than nature. Any dog can become aggressive in response to its environment. The reason many people assume large and giant breeds are more aggressive than smaller dogs is due strictly to their size. Compared to smaller breeds, large dogs are taller (especially when they stand up on hind legs), their mouths and teeth are bigger, their barks sound more serious, and their bodies are more powerful. The reason we hear more about aggressive large dogs is because they cause more harm when they bite, not because they bite more often than their smaller counterparts. It's similar to an airplane crash – it doesn't happen often, but it makes a good news story when it does.