http://www.realpitbull.com/myths.html
"Pit Bulls have locking jaws." The jaws of the Pit Bull are functionally the same as the jaws of any other breed, and this has been proven via expert examination.
The few studies which have been conducted of the structure of the skulls, mandibles and teeth of Pit Bulls show that, in proportion to their size, their jaw structure and thus its inferred functional morphology, is no different than that of any [other] breed of dog. There is absolutely not evidence for the existence of any kind of ’locking mechanism’ unique to the structure of the jaw and/or teeth of the American Pit Bull Terrier, says Dr. I. Lerh Brisbin of the University of Georgia (from the ADBA booklet, “Discover the American Pit Bull Terrier.)
"Pit Bulls can hold on with their front teeth while chewing with their back teeth." As stated above, the Pit Bull’s jaws are, functionally speaking, the same as all other breeds.
“Pit Bulls don’t feel pain.” Pit Bulls have the same nervous system of any other breed, and they can and do feel pain. Historically, those dogs that would tolerate or ignore discomfort and pain and finish the task they were required to perform were the dogs that were bred and the sort of dogs breeders strove to produce. This is the trait of “gameness” that so many breed fanciers speak of, which may be defined as, “The desire to continue on and/or complete a task despite pain and discomfort.”
“Pit Bulls have more bite pressure per square inch (PSI) than any other breed.” This is pure speculation at best, damaging myth at worse. There have been no exhaustive studies conducted to prove that Pit Bulls have the strongest jaws of any breed. There likely could not be any truly conclusive testing done to measure something like strongest breed PSI. A reason for this lies in the fact that dogs bite with varying pressure depending upon the situation, and what factors are driving the bite at that particular point in time. A dog cannot be instructed to bite down on a measuring device as hard as possible, so a tester could have no way of knowing whether or not a particular dog being tested is actually using its jaws to capacity in any given testing phase. There is also large size variation in any breed, and one must assume strength varies as well. A very large (but not typical or standard) Pit Bull may bite harder than a small Rottweiler, German Shepherd, or other breed, while a standard sized Pit Bull may not have as much jaw power as a larger, typical sized Rottweiler, etc. Also, if one breed is to claim “highest bite pressure”, all breeds would have to be compared. All 500+ of them.
Dr. I. Lerh Brisbin of the University of Georgia states, To the best of our knowledge, there are no published scientific studies that would allow any meaningful comparison to be made of the biting power of various breeds of dogs. There are, moreover, compelling technical reasons why such data describing biting power in terms of ‘pounds per square inch’ can never be collected in a meaningful way. All figures describing biting power in such terms can be traced to either unfounded rumor or, in some cases, to newspaper articles with no foundation in factual data. (From the ADBA booklet, “Discover the American Pit Bull Terrier.)
“Pit Bulls attack more people than any other breed.” Bite statistics are difficult to obtain accurately. Dogs that are referred to as “pit bulls” in statistical reports actually are a variety of breeds and mixes all lumped together under the “pit bull” heading. Also, many people have a difficult time properly identifying a true Pit Bull, so added to the statistics are those dogs that have been misidentified. Considering these factors, the actual number of attacks attributable to American Pit Bull Terriers is considerably lower than represented. Also important to understand is the extreme popularity of the Pit Bull and pit bull-type breeds. By some estimates, numbers-wise they are the most popular of all dog breeds. It is only logical to assume that the breed with the higher number of individual dogs would be represented with a higher number of bites. Viewing older statistical reports for the Center of Disease Control, one will see that trends in breed popularity reflect in the number of bites attributed to a specific breed during a specific period of time.
“The brains of Pit Bulls swell and cause them to go crazy”. Prior to the boom in Pit Bull popularity, the Doberman Pinscher was rumored to suffer from an affliction of the brain in which the skull became too small to accommodate a dog’s grey matter. This would, according to the rumor, cause the Doberman to go crazy, or “just snap” out of no where and attack their owner. This rumor could never be quantified, and indeed had no merit whatsoever. Now that the Doberman fad has run its course the Pit Bull has inherited the swelling brain myth. It is no truer now than it was during the Doberman’s fad days.
“Pit Bulls ‘turn’ on their owners.” Dogs, as a species, do not perform behaviors “just because”. There are always reasons for behavior, and when aggression becomes a problem the reasons can be such things as improper handling, lack of socialization or training, a misreading of dog behavior by the owner, or, rarely, disease. Aggression, when it presents in pet dogs, follows specific patterns. First occur warning signs, then more warning signs, and finally, when those signs are continually ignored or misinterpreted, the dog resorts to using its teeth. When an owner is startled by a sudden, aggressive outburst, it is because they have been unaware of problems that were brewing. This is true of all dogs, not just Pit Bulls. Pit Bulls, indeed no dogs, “turn” on their owners.
“The only thing Pit Bulls are good for is dog fighting.” Unfortunately, a large amount of attention has been brought to the fact that the Pit Bull was originally created for fighting other dogs in the pit. Since the breed was selectively bred for and excelled at this task, there is a common assumption that fighting must be all for which the breed is good. The truth of the matter is that the Pit Bull is one of the most versatile of canines, capable of excelling at just about any task his owner asks him to complete. This breed is routinely used for: obedience trialing, conformation showing, weight pull, Schutzhund (a German sport which requires dogs to perform in obedience, tracking and protection phases of a competition), agility, and have even been known to participate in herding trials, search and rescue work, and a variety of other tasks including police and armed services work. But fanciers will argue that the task this breed performs best of all is that of beloved companion.
"Dogs that are aggressive towards other dogs are aggressive towards people." Human aggression in dogs is entirely different than aggression directed at other animals. Inter-dog aggression is a normal trait of the breed (as it is in many terrier breeds, among others). Historically, humans were always in the pit, handling fighting dogs closely, while the animals were in full fight drive. A dog that was a danger to people and prone to biting was not feasible, and therefore carefully selected against.