I am having a problem with my chickens. I have 12 hens and no roosters. In the last 2 weeks I have had 2 hens that seem to have a "bum" leg. The first one happened last week, she was a barred rock hen that is about 10 months old, I went out and she would not put any weight on her leg. When I went to check on her later she had not moved from where she was in the morning and when I got her to move she was dragging her foot. I went out this morning to find one of my other hens (same age) not putting any weight on her leg. I am not sure what to think of this...are they hurting each other or have they gotten into something? They are in a large fenced area and are locked in the coop at night. I have several places for them to roost and the floor is covered with straw. I have looked all around the coop and I cannot see anywhere that they would be getting stuck or landing on when they leave the roost. I have not seen any evidence of a predator getting in. I have seen evidence of some mice in my coop and I have traps around the outside but not anywhere that the chickens can get to them. I have not put poison out for the mice. I live in Colorado so it has been getting cold at night, I don't know if this matters but I am trying to include as much information as I can.