American Staffordshire Pit Bull Terrier
Am Staffs are strong-willed dogs and very powerful and require a lot of attention from their owners.
If not, this animal can become destructive when they are bored and can become aggressive.
Like many other dog breeds, aggression towards other animals is the biggest issue with the Am Staff.
As long as the dog comes from a reputable breeder, the animal will not become aggressive to other humans.
Because these animals were bred to fight, if they feel threatened by another dog, they will become aggressive.
These dogs aren't the biggest on the list, but they can weigh up to 80 pounds and stand 20 inches at the shoulder and clamp down on something with bite pressure of 235 pounds per square inch!