I went out to get the eggs this morning and immediately noticed that one of my buff Orpingtons wasn't acting right. she was laying in the corner of the run and unable to walk. When I opened the coop, I found my other orpington dead. Both of these chickens seemed fine yesterday and the rest of my chickens seem fine as well. I checked both of the orpingtons and there's no blood, no broken bones or any other signs of injury or sickness. I felt around the vent/underside of the Orpington who is still alive and she isn't eggbound. She is missing some feathers around her belly but other than that I can't find anything physically wrong with her. She still wants to eat, but she won't drink and is unable to walk. I'm at a loss as to what would cause this and I'm worried that I might lose all of my chickens. Does anyone know what this may be? And how I can prevent it from happening to the rest of my chickens? Edit: I'm not sure if this is just a coincidence or not, but these 2 chickens are my only orpingtons. The unaffected chickens are all different breeds. They're 2 years old.