The Bulldog Standard
"The nose should be large, broad and black, its tip set back deeply between the eyes. The distance from bottom of stop, between the eyes, to the tip of nose should be as short as possible and not exceed the length from the tip of nose to the edge of underlip. The nostrils should be wide, large and black, with a well-defined line between them. Any nose other than black is objectionable and a brown or liver-colored nose shall disqualify."
Bulldogs belong to a group of dogs know as "brachiocephalic" breeds or "short-nosed" breeds. Since dogs do not sweat to cool themselves as people do they rely on panting to help expel excess heat. The short nosed breeds cooling mechanism and air transfer is much less than other breeds. Being aware that your Bulldog needs attention to avoid overheating is an important role for you as owner.