The American Bulldog is a large breed of utility dog descended from the now-extinct Old English Bulldog. American Bulldogs also successfully compete in several dog sports such as dog obedience, Schutzhund, French Ring, Mondioring, Iron Dog competition and weight pulling. To a dog, a baby does not smell like an adult human and thus he must be taught before the baby arrives that this odd, squealing and strange-smelling creature is precious to the master and that the master is to be minded when he commands the dog to leave the nursery, 'heel', or 'leave it': American Bulldogs are a breed with a background as a guard dog and thus this step should not be ignored or skipped, especially when evidenced by its weight being heavy enough to knock over a cradle in its over-exuberance and high sensitivity to unfamiliar things: he has to learn that this weird thing is a human version of a puppy and that baby is too little to play rough .