Dogs are predators so hunting is a natural instinct. That does not mean, however, that your dog has to busily express this instinct by catching and eating poultry. It might be upsetting if the chickens are your own, but if they belong to somebody else, you risk legal trouble. A habit like this also puts your dog in danger. People do not respond well to dogs eating their animals.
Separate the dog from the chickens immediately. If you have chickens of your own, do not allow your dog unsupervised access to the yard at the same time as the chickens. Either lock up the chickens or put your dog on a short leash every time he has access. If he is killing other people’s chickens during walks, revert to a short leash and take a route that does not take you past poultry.
Begin chicken training, if your dog is not a habitual poultry killer. If he is, it might be better to continue with complete separation, at least until you have arranged sessions with a professional dog trainer. There is no need for him to become best friends with your chickens if he’d rather eat them. To begin chicken -- or any other animal -- training, locate a spot where there are chickens wandering about, but not too close. Ask permission if this spot, and the chickens, are not yours.
Take your dog to the chicken site on a short leash. As soon as he shows any interest in a chicken, even just looking, call his name and walk rapidly away from the chicken. Once you are out of sight, provide praise and possibly a treat. Engaging in his favorite game also helps.
Repeat this procedure over a period of at least a few weeks, gradually allowing the chicken encounters to become closer. Once you are certain that he is showing little interest in the birds, start increasing the length of the leash, but do not let it trail.
Take him into the yard on a short leash if the chickens are yours. Let the chickens out, but tell your dog to sit and maintain constant eye contact. He should be focusing entirely on you. Keep these sessions very brief to begin with, gradually increasing the time period. Asking him to perform a trick or two that he already knows would help him concentrate. Terminate a session immediately if he makes any moves towards the chickens.
Attach a long line to his collar and let it trail while he walks near chickens, but only if he was not a habitual chicken killer and the chickens are yours or you have full permission from the owners to conduct this training and they are aware of this step. If he shows interest in a chicken, pick up the end of the line as a precaution but leave it loose. Call his name and get his attention focused on you before walking away to do something else.
Allow him to run free near chickens once he starts showing no interest in them, but only if they are yours, and always supervise him. A dog who has killed a chicken once might again, especially when he thinks nobody is looking. The urge to hunt is a powerful one and everybody has moments of weakness.
Book a series of sessions with a professional dog trainer, preferably one who has extensive experience of training dogs to behave nicely around other animals. Ask your vet, friends, local breeders or local dog clubs for recommendations and check the trainer’s qualifications. According to the ASPCA, the qualifications to look for in a dog trainer are: CPDT (Certified Professional Dog Trainer), CAAB (Certified Applied Animal Behaviorist) or a board-certified veterinary behaviorist (Diplomate of the College of Veterinary Behavior, Dip ACVB).