The data on Nanny Dogs is in

No.14382884 ViewReplyOriginalReport
>Of the more than 8 different breeds identified, one-third were caused by pit bull terriers and resulted in the highest rate of consultation (94%) and had 5 times the relative rate of surgical intervention. Unlike all other breeds, pit bull terriers were relatively more likely to attack an unknown individual (+31%), and without provocation (+48%).

https://pubmed.ncbi.nlm.nih.gov/25311183/