History: I have 6 hens, all approx 8 mo old. They're laying good except for 1 whose been molting for 3 months now. About Thurs, I noticed my EE (molter) was laying down more. Didn't notice her limping until Friday evening. Today, it seems worse and then I also noticed my Lt Brahma is doing the same thing but not as severe. She is still foraging as normal. They free-range a little bit in my small yard but are not exposed to other hens in our neighborhood. I haven't been to any other farms in a long time. How do I determine if it definitely Marek's? They are not vaccinated. Do I vaccinate now? Do I have to kill them at all? I tried googling information but it seems so vague for all my questions. You guys are the best and I trust your wisdom here. I don't write much but I do read.