This is a cautionary tale: I bought some replacement pullets from a farmer up the road. He keeps his chickens in very clean conditions. However, he has about 100 or more chicks/pullets at a time and does not vaccinate. I don't really blame him since we live in an area where the thought seems to be "don't vaccinate" and it's easier to sell non-vaccinated chickens. I also keep my chickens in clean conditions. About 5 days ago, one of the replacements came up lame. She had only just started laying. I isolated her from the others by way of a chicken tractor in the hen yard. The first day she got slightly better. I think this may have been because the other hens weren't beating her up; after the first day she went downhill. She had stopped trying to get to food and water (near her) yesterday although she'd peck a little scratch from the ground if right in front of her. She didn't want to move but could if necessary, hobble around with the help of one wing. She responded to pressure on both feet and no signs of bumblefoot, sprain, break, etc. I picked up some antibiotic but didn't give it since there were no respiratory symptoms or diarrhea. I fed her high calorie food for omnivores by syringe. I talked to 2 vet's offices without much success. BTW, the livestock vet would put her down via injection into the heart after gas sedation. I then called the poultry extension agent who thought it was Marek's disease. (That had also been my conclusion though I had some questions.) He told me we don't get cloudy eye/blindness and we also don't usually get lesions. Most often, it takes a necropsy to find the swelling in the legs and joints as well. He said the hen becomes lame or paralyzed and just stops moving around, eating and drinking. It is a slow death from a Herpes virus/cancer for which there is no cure. It isn't contagious to humans. She was not going to recover. I decided to put her down rather than have her sit all day in 90 degree heat not able to get to food or water, (although she did have shade). Putting an animal down is a miserable job no matter how you do it. Here's the moral: Only buy chicks and pullets that have been vaccinated for Marek's disease. It's not a guarantee but it does offer protection to most of them.