I went in to bring fresh water for our girls and saw blood outside and in the shed. I went in and got my husband to help me find out where it was coming from. It was quite a bit. One of the chickens was on the perch and there was blood on her foot, and also looked like some on her neck. Also found a couple others with blood coming from their feet. We looked around and can't find anything inside or outside that would have cut them. Any ideas? Could it be the cold? Should I do anything or put anything on their feet to avoid infection? This is the first time something has happened since we've had chickens I have no clue how to take care of it. Please help with advice.