It's a pup. It's curious, and will chase just about anything that moves because it's trying to PLAY. The problem is that chickens are not play toys, and can easily be hurt, or killed in the process. Start with a collar, and leash. Walk your pup on the leash whenever it goes outside. Within two weeks it will begin to work with you some, and quite fighting the leash. At this point, begin carrying a rolled up section of newspaper, and still on the leash, walk the dog near the coop. If it barks, swat with the newspaper, and tell it NO, firmly. If there is no barking, don't swat the dog. Do this for a couple days to make sure there is no barking at the chickens. At this point, enlist the help of another family member. They need to get and hold a chicken, while sitting down just outside the coop. With the dog on a tight (don't choke the dog) leash, and slowly approach the family member, and chicken, but keep a little distance. If the dog pulls hard on the leash, overly anxious to get to the chicken, tug firmly on the leash. If dog refuses to settle down, swat with newspaper, and say NO, firmly. Walk past the family member, and chicken. Turn around, and again walk slowly past the family member, and chicken. Repeat this process 3 - 4 days until the dog can see the chicken without trying to lunge for it. Now, you are ready to introduce the dog to the chicken. Continue as you have been doing, only this time, walk up and talk to the person holding the chicken. If the dog gets overly excited, tug at the leash, and continue walking, then turn around and repeat. As soon as you can approach the person holding the chicken with the dog, and the dog doesn't get overly excited, allow it to get near enough to sniff the chicken. You, and the person holding the chicken should be ready to swat the dog with the newspaper, and tell it NO, if it tries to grab the chicken with it's mouth. Repeat this for a week, trying not to use the same chicken each time. By now the dog should have settled down around your chickens. If you free range, walk him on the leash with the chickens outside. Don't let him bark, or try to chase them. If he does, a swat with the newspaper, and a firm NO should be used. Continue walking the pup in the yard on the leash, while the chickens are out, for a couple more weeks. At this point, you may slowly walk up to the chickens. They may move away, but the pup is not to try to grab them, or run after them. Yes, it will take some time, and effort, but if you dedicate the time to teach the dog now, you will be able to enjoy having it around for the rest of it's life without fear of it harming your chickens.