I had a sick chicken that I had posted on. Someone suggested Marek's disease. I finally had my son to put that hen down as she was not getting any better (had her here in the house in a plastic tub). I was out letting them all free range yesterday evening and giving them bread, and notices some foamy poo on the rear of a silver laced wyandotte. She was acting a little off, but was eating. It has been pouring, and has let up so I went out to let them out and put some food in their feeder, and the Wyandotte was laying out there dead.....she has not been dead long, was still warm underneath her. I am totally freaking out. From what I was reading, they can get a different strain of Marek's even if vaccinated. At this point, I don't know what to do. These vets here no nothing of chickens. I got in touch with the agriculture person and she won't come out if not respiratory.