The nose of the bulldog has been slanted backwards so that he can breathe without letting go.
It is believed that man’s first interactions with dogs (wolves at the time) resulted in a beneficial relationship for both species. The wolves got easy pickings from the scraps that people left behind after their meals and people got the benefit of having the wolves around to protect them from any other predators that may prey on those people. In more recent times, dogs were trained by the military as sentry guards, protecting troops from attack. And as silent scouts, dogs would warn troops to the presence of enemies, diminishing the chances of an ambush. The troops lucky enough to have these attack dogs by their sides were most likely to survive war. From puppy-hood, dogs innately learn to watch and be aware of anything rotten coming your way. Potential burglars are put off by a barking or watching dog in the window.