land shark

A word often used to describe dangerous dog breeds such as Bullterriers (Pitbull, Stafford) and Mastiffs (Rottweiler, Dogo Argentino, Boerboel) because they tend to have large jaws, sharp teeth and muscular bodies, which goes with the ability to severely injure and kill other humans and animals.

"My crappy neighbour recently bought an American Pitbull Terrier, the jaw was so huge that it reminded me of some kind of land shark. I heard they kill more people than all other breeds combined!"