I'm sorry you lost your chicken.
I too understand wanting a good dog. I have quite a few animals indoors and out, and it's been very hard for us to find the perfect dog. I wasted a lot of time with rescues, adult dogs, and hoping to train the wrong breed to do the job I needed. I finally wised up, found good homes for the problem dogs, and got a livestock guardian dog (LGD).
This is one area where you need to be very, very careful and get a dog that is bred to the purpose: which is guarding animals. I would not get an adult dog, even of a LG breed. If the dog has not been raised around the livestock you want it to guard it might see it as a snack or a toy. I also would not get a dog from a pound/rescue that claims it's 'X' breed without really knowing. I just don't think it's worth the risk. I have a friend that has a Pyr/Heeler mix. No way would I ever trust that dog around my chickens. Never know when the heeler part might come out and make the dog want to chase and kill.
There are a lot of great dogs out there of many different breeds that for what ever reason will not hard small livestock, but they tend to be the exeptions. Everyone has a story about their heeler (lab, border collie, pit bull, etc.) that wouldn't hurt a fly. Maybe so. I'm not going to chance it!
So, we bought a gorgeous Great Pyranees x Anatolian shepherd LGD puppy. I like the cross, I'm hoping for a little hybrid vigor (and less hip problems than the pure breds). Either breed mixed or alone makes a wonderful livestock guardian dog with proper training and socilization. We got Koda at 11 weeks old and have been very careful to properly introduce him to all our outside animals (horses, cows, chickens, turkeys and cats) so that he knows from the start what he's allowed to harass and what he isn't. He's 14 weeks old now and I'm just amazes at his temperment. He gets bouncy and silly like all puppies do, but he does not have the prey drive that every other breed of dog I've ever owned has had. He's not 100% reliable around all the animals yet, but he's still young and learning. His urge to protect is already very much there even as young as he is. In another year or so he's going to be a wonderful guardian dog.
But, it's going to take a lot of time and training on my part to get him there.
Oh, and at 14 weeks he's already 30 lbs. Should top out around 100 lbs. Big investment in time and dog food!
Liz