https://www.livescience.com/27145-are-pit-bulls-dangerous.html
"A five-year review of dog-bite injuries from the Children’s Hospital of Philadelphia, published in 2009 in the journal Plastic and Reconstructive Surgery, found that almost 51 percent of the attacks were from pit bulls, almost 9 percent were from Rottweilers and 6 percent were from mixes of those two breeds.
In other words, a whopping two-thirds of the hospital’s dog-attack injuries involved just two breeds, pit bulls and Rottweilers.
Other studies confirm these statistics: A 15-year study published in 2009 in the American Journal of Forensic Medicine and Pathology revealed that pit bulls, Rottweilers and German shepherds were responsible for the majority of fatal dog attacks in the state of Kentucky. [See What Your Dog’s Breed Says About You]
And a 2011 study from the Annals of Surgery revealed that “attacks by pit bulls are associated with higher morbidity rates, higher hospital charges and a higher risk of death than are attacks by other breeds of dogs.”
The authors of that 2011 study go on to say, “Strict regulation of pit bulls may substantially reduces the U.S. mortality rates related to dog bites.”"
"Pit bulls join several other breeds on the list of dogs that are recognized as more likely to attack and cause significant injury: The Centers for Disease Control and Prevention analyzed data and found the following breeds are implicated in a majority of dog-bite fatalities:
Pit bulls
Rottweilers
German shepherds
Huskies
Wolf hybrids
Malamutes
Doberman pinschers
Chow-chows
Saint Bernards
Great Danes
It’s worth noting that no matter how these data are arranged — mixed breeds versus pure breeds, injuries versus fatalities — pit bulls consistently rank at the top of the list for attacks, and by a wide margin. (Rottweilers generally rank a distant second.)"
"What exactly is a ‘pit bull’?
The term “pit bull” is a general term encompassing three distinct, though related, breeds: the American pit bull terrier, the American Staffordshire terrier, and the Staffordshire bull terrier.
They were originally bred as “catch dogs” for hunting and attacking large animals like wild boar, for herding livestock and for pit fighting."