There is no formal breed directly called "pit bull." Rather it's a term applied to a type of dog that derives from the heritage (old) breeds of American Staffordshire terrier or Staffordshire bull terrier. Similarly, the American pit bull terrier often falls under the "pit bull" umbrella.
Dogs designated as pit bulls are often considered by the public as dangerous by their very nature, a risk to children and other dogs. The study's researchers suggest, however, that dog breeds have a variety of genetic traits that make it impossible to offer predictions about how one dog will behave.
"A dog's physical appearance cannot tell observers anything about its behavior," said Levy. "Even dogs of similar appearance and the same breed often have diverse behavioral traits in the same way that human siblings often have very different personalities."
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The study's results, according to Levy, "raise difficult questions because shelter workers and veterinarians are expected to determine the breeds of dogs in their facilities on a daily basis. Additionally, they are often called on as experts as to whether a dog's breed will trigger confiscation or regulatory action. The stakes for these dogs and their owners are in many cases very high."