I've got two German short-haired pointers. They are natural bird hunting dogs and I hunt with them. They also chase squirrels, chipmunks, frogs, deer, etc. They kill field mice daily. My point is they have an incredibly high prey drive. We have about 40 free range chickens and ducks. It took training and lots of attention, but the dogs have peacefully coexisted for 4 years now. They did kill a chicken early on, but that's on me. Shock collars are the way to go, with ALOT of attention at first. Now, I let them out amongst the chickens unsupervised for hours with no worries. They have learned that if they lay in the woods and watch the chickens from afar, sometimes a fox will show up and it's game on. I've even got a duck that will lay next to my male on sunny days and peck him occasionally. I wouldn't give away/put down your dog until you've done everything you can to teach them to behave. It also sounds like your dogs didn't do wrong until you weren't around for awhile. Maybe try boarding them if your going to be gone more than a day. Good luck!
