It helps to creates a bond (yeah she may be dead) if constant exposure to your hens is not working.
I did this with my dog once, all it took was one day. He had this chicken following him where ever he went around his neck. Now he is way over protective of them. He hears the hens singing, and...
Tie one of the dead hens around his neck where he cant reach it. Shock collars do work, but you might not always be around to push that button. Shock collars can also induce agression in some breeds.