As far as the American Kennel Club is concerned, there is no such thing. The AKC recognizes the Staffordshire bull terrier and an American Staffordshire terrier, both of which have blocky heads, wide jaws, broad shoulders and barrel chests. They’re born with floppy ears, which some owners crop to triangular points.

Both breeds compete at the Westminster Kennel Club show.

Other kennel clubs recognize the American pit bull terrier as a discreet breed. The American pit is likely “a cross between the original bull dog and the extinct English white terrier,’’ according to the Animal Planet ‘Dogs 101’ guide to “pits.’’

All the rage in Victorian England, the English white is believed to have contained genes from the fox terrier and Italian greyhound.

The guide describes the APBT as “a solid, athletic dog with a short, smooth coat [and] while every dog has his own personality and attitudes — some as a result of breeding, some of the way the dog was raised — [they] are loving, gentle, cuddly family dogs who love attention and enjoy being with people.’’

For centuries, pit-type dogs were selectively bred to fight, initially bears and bulls, then after bloodsports were outlawed, each other. They were likewise engineered not to attack the humans who handled them.

APBTs won’t back down from a fight, the guide notes, and “what another dog starts, the pit will definitely finish.’’