The mere act of chaining the dog up like that will make an already vicious animal even more vicious.
Yes, and for sure! And these people did not recognize this? Good grief, folks - wake up to 'dog realities' if you have one; moreso; if you have one that is riled to 'madness' easily; better, for sure; not have one of these dogs to begin with.
(There is no way to trust a potentially dangerous dog or to contain said dog, safely and humanely).