This is an extract from a US non-profit created to educate about dangerous dog breeds. Clearly, they have an agenda, but they do use evidence based material/case law citations:
www.dogsbite.org/dangerous-dogs-pit-bull-faq.php#bitestyle
Q: Why do people say that pit bulls "don't let go?"
^Through selective breeding, pit bulls have developed enormous jaw strength, as well as a ruinous "hold and shake" bite style, designed to inflict the maximum damage possible on their victims. This bite trait delivered winning results in the fighting pit. When the Colorado Supreme Court upheld the Denver pit bull ban in 2005, the high court set aside characteristics that pit bulls displayed when they attack that differ from all other dog breeds. One of these characteristics was their lethal bite:
"[pit bulls] inflicted more serious wounds than other breeds. They tend to attack the deep muscles, to hold on, to shake, and to cause ripping of tissues. Pit bull attacks were compared to shark attacks." - Kory Nelson, One City's Experience15^
^Leading pit bull education websites, such as Pit Bull Rescue Central, encourage pit bull owners to be responsible and to always carry a "break stick" a tool used to pry open a pit bull's jaws in case their dog "accidentally" gets into a fight. These same websites also warn that using a break stick on any other dog breed may cause serious injury to the person.16 This is true because no other dog breed possesses the pit bull's tenacity combined with a "hold and shake" bite style.
One of the most powerful examples of a pit bull "not letting go" occurred in an Ohio courtroom. During the Toledo, Ohio v. Paul Tellings trial (Tellings was convicted of violating the City of Toledo's pit bull ordinance), Lucas County Dog Warden Tom Skeldon showed a videotape of a tranquilized pit bull hanging from a steel cable. The dog is essentially unconscious and still does not release its grip. At the time of the taping, the pit bull was being housed at the Lucas County Animal Shelter.^
Q: Do pit bulls bite more than other dog breeds?
^Depending upon the community in which you live and the ratio of pit bulls within it, yes and no. But whether a pit bull bites more or less than another dog breed is not the point. The issue is the acute damage a pit bull inflicts when it does choose to bite. The pit bull's "hold and shake" bite style causes severe bone and muscle damage, often inflicting permanent and disfiguring injuries. Moreover, once a pit bull starts an attack, firearm intervention may be the only way to stop it.
When analyzing dog bite statistics, it is important to understand what constitutes a bite. A single bite recorded and used in dog bite statistics is a bite that "breaks the skin." One bite by a poodle that leaves two puncture wounds is recorded the same way as a pit bull mauling, which can constitute hundreds of puncture wounds and extensive soft tissue loss. Despite the "quagmire" of dog bite statistics, pit bulls lead biting incidents across U.S. cities and counties.^