Quoting Jude ♥ JGL:" Never would I risk my life for a dog like that. Maybe if I had a large stick to beat the other dog but would that be wrong too? Uou can bet that the dog's owners would be replacing my pet though."
They don't care...I've seen some horrible dog fights (not illegal ones) and with exceptions depending on their temperament, breed, etc, most block out external stimuli when fighting. I've tried this method before and the stick, which was huge, broke before the dog let go.
There is a thing called a "breaking stick" that's usually a hammer handle that is sawed or shaved into a V shape at one end. You use it on the dog that has the hold. It's inserted into the side of the mouth between the back molars and then pried upwards for a release.
Collars are tools too. If it's twisted enough, it chokes the dog out. Yeah, it sounds horrible but if he can't breathe, he can't fight.