Rottweiler
Rottweilers were bred for their strength. They were used for pulling carts and herding livestock. They’re loyal animals but have a tendency to react violently towards strangers. They have strong personalities and need strict training in order to control them.
Bullmastiff
Bullmastiffs can grow to be very large and can be aggressive, which can pose a risk around small children. They don’t seem to be aware of their size so can knock kids down and trample on them without realizing it.