There is no evidence for the existence of a physiological "locking mechanism" in the teeth or jaw structure of normal pit bull-type dogs,[33] although a dog's jaws can be locked in a closed position by surgically correctable jaw abnormalities.Despite the lack of a physiological "jaw locking" mechanism, pit bull-type dogs often exhibit "bite, hold, and shake" behavior and refuse to release when biting; methods to force pit bull-type dogs to release their grip include breaking an ammonia ampule and holding it up to the dog's nose, or using a "break stick" to lever the dog's jaws open if it bites a person or animal.
