My red heeler male does great with our chickens. He has a very high prey drive, no fence not issue. Heck he helps eat their food. Take time to teach him. Or get rid of him. It's not fair to either to have to live in fear
He's a sweet looking dog. Shock collars do work if used correctly. I also have had a very tough hen peck on cats and dogs that are too interested. With a few rare exceptions, most give the chickens more space after that.
My dog is like a nanny to them. I have to be careful when she wants to clean them or give them kisses as chicks...
I had a dog named rusty who attacked my buff orpington hen. Fortunately, she was a survivor. Some dogs who chase or go after chickens are really just chickens themselves. I have had dogs charge after them and the chicken ends up backing them down.