This is why:
© Merritt Clifton, editor, Animal People
Pit bull terriers and Rottweilers together appear to commit about two-thirds of the reported serial attacks on humans (65%), and more than three-fourths of the rampage attacks (79%), ANIMAL PEOPLE has learned, in a review of files on approximately 1,500 dog attacks in cases in which a person was killed or maimed, or police shot the dog.
Serial attacks are defined as instances of a dog injuring someone after having injured a person or an animal on a previous occasion. ANIMAL PEOPLE found that about 5% of the dogs involved in life-threatening or fatal attacks on humans, or shot by police while attacking, had attacked a person or killed a pet on an earlier occasion.
Among the 59 dogs who flunked a second chance after biting a person or killing a pet were 28 pit bulls (48%), 10 Rottweilers (17%), and 21 dogs of 10 other breeds.
The lopsided risk associated with giving pit bulls a second or third chance would be even greater if pit bull advocates are correct in asserting that pit bulls are more likely than other breeds to be killed after their first violent incident--which would mean that relatively few pit bulls get further chances, and that those who do are among the dogs considered least likely to be genuinely dangerous.
However, the rates of flunking second and third chances among pit bulls, Rottweilers, and other breeds were all closely comparable to their overall rates of involvement in life-threatening incidents, fatalities, and police shootings of dogs. This suggests that neither pit bulls nor Rottweilers are subject to statistically quantifiable discrimination in deciding which dogs get extra chances.
Rampage attacks are defined as instances of a dog attacking multiple people or animals during a single incident. About 10% of the dog attack cases in the ANIMAL PEOPLE files involve rampages in which a person is killed or maimed, and/or the dog is shot by police. Of the 153 dogs who rampaged, 89 (58%) were pit bulls; 32 (21%) were Rottweilers; and 32 (21%) were representatives of 14 other large breeds.
No dog smaller than a boxer was involved in a rampage attack, possibly because small dogs are more easily restrained after attacking their first victim.