Training an adult dog who has never been around chickens can take more time and effort then raising a pup around chickens. A smart older dog quickly learns that chickens in their run are boring so he may ignore them, but let one of them be seen outside the fence or running around and game on. So in that regard what you need to do is MORE contact, not less. Daily, restrained exposure is how I raise my ranch pups to be good farm dogs. They go right into the pens with me among the chickens to do chores etc but pup is on a leash attached to me at all times so I can quickly nip bad behavior in the bud and reward good behavior, i.e. ignoring the birds. This goes on for as long as it takes for pup to get bored with it all. Chickens become old news and pup learns that I expect him to leave the birds alone. He then graduates to running along with leash dragging, provided he has by then proven willing to listen to me even in the face of great temptation lol. With the breeds I keep this usually comes pretty easy, with some dogs it may take a long time and some dogs will never be trustworthy around chickens. Breed has influence but temperment and training are key.
