We live in Northern Utah. We purchased 6 Leghorn pullets in early November. We are down to 2. One was attacked by a dog and lost many feathers, we assumed at the time that between the trauma of the attack and the bitter winter she didn't survive. One was snatched by a hawk. The last 2 are a mystery. They actually have exhibited the same signs as the bird that was traumatized by the dog attack. They just slow down, pretty soon they don't come out and free range like the rest and then they end up just sitting on the floor of the coop. They stop moving, you can actually touch them and they just fall over. I have 3 older sex link hens and they are completely fine. Did I happen to get some chickens that have some bad traits?