Check your local animal care ordinances re permissible chain weight. The size of that thick, heavy chain might be illegal, depending in where you are (too heavy). A call to animal control might conceivably spring her from that life...and into your arms when she becomes adoptable at the shelter.
I know of at least one state that allows prosecution for too-heavy chains under cruelty laws (since the weight can severely damage the neck and spine). I don't think most will, though.