This is going to sound a little crazy but worked for my mum. She had a lab and a jack russell and then got 4 chickens. She was told to hold chicken and dog firmly and bounce bird up and down a few times on the dogs head!!!! Its something to do with establishing dominance, don't pretend to understand it. Her 2 dogs watched the birds from a distance but never tried to catch or attack them. I've got chickens too and did same with my cats, but don't think they were ever that interested in the first place, far too busy catching mice.