Here is my 2 pennys. If you have an animal that is charging you. You need to be the aggressor. If you are protecting someone or another animal, You need to present a target. It is like a Knife fight ( No one ever wins). Once a dog gets a hold of a target, As long as it is moving, He won't let go. You need to decide what target you want to present, Not the animal.
I have worked as a ( Agitator) Helper with numerous breeds of dogs. I have owned 5 Rotties and have caught Shutzhund 1-3 dogs on a sleeve.
Ivan