Nanny dog was a nickname for pit bulls, because they were considered the perfect dog for children. Because of the breed's friendly, non-aggressive and loyal nature, pit bulls were thought to be a good breed to suit rambunctious children.
Pit bulls are often portrayed negatively in the media because some owners train them to be aggressive, either for home defense or for violent acts such as dog fighting. Because of this reputation, pit bulls have been one of the most abused and misunderstood breeds in the United States. Although the breed is friendly and loyal when treated properly, many people now think of the breed as naturally aggressive rather than as a nanny dog.