The diagram above shows the correct skull structure, jaw alignment, and dentition for mesocephalic breeds of dogs. Mesocephalic refers to those breeds whose length of muzzle approximates the length of the top skull. These breeds when correctly structured have a scissors bite, with the top teeth meeting tightly in front of the bottom teeth.
Most of the breeds of dogs lumped under the ubiquitous heading of “pit bull” are mesocephalic, but some are not.
There is no supernatural structure to these breed’s skull, jaw, or teeth. That any dog is capable of locking its jaw is a myth.
Sound, correct dogs have 42 teeth after the seven month molars erupt. Dogs may exhibit malocclusions, or genetically missing teeth, usually pre-molars.
There are two more types of skull that are displayed in dogs. The brachycephalic which is the very short faced seen in breeds such as the Bulldog, Pug, Boston terrier, Pekingese, American Bulldog, etc. These breeds are predisposed to malocclusions, and to missing teeth due to crowding. These breeds are prognathous jawed, with the lower teeth protruding in front of the top teeth.
The dolichocephalic type of skull is long, and narrow, the muzzle is longer than the top skull. It is common in breeds such as the Borzoi, the Bull Terrier, and the Collie. The long narrow jaws appear to be able to hold more teeth, but these breeds also have 42 teeth.
These are the facts about dog skull configuration.