That is insane and I think criminal. That dog should never be in a no-kill shelter and there should be no debate about its future. It does not matter what the cause is of the behavior. Of course there needs to be a rabies assay, but I am sure you can determine that after a dog is dead. And the owner should face severe legal justice and never ever have a dog again. Or a wildebeast, cougar, boa constrictor or whatever. mg