I'm loosing my 3rd young chicken (around 5 months old) to something similar to Mareks, but she came vaccinated. These were "show quality" violet Americaunas, and one day she just lay in the run all day. I have since brought her in and rehydrated her. She still just can't walk as much as the others, her legs seem very stiff like a partial paralysis. I'm trying to get hold of the breeder, with no luck so far. My research points to a virus such as Lymphoid Leukosis that can actually get into the dna and affect any chicks hatched from their hens. Anyone have any knowledge of this? Also how to move forward. Do I just put this one out of her misery. I have only 1 left after this that I expect to come down with this as well, we've had to detach from these hens emotionally. Is this something the ag exemption is interested in? Any help appreciated. Thanks! Also, I have 2 dozen others that were acquired elsewhere (many unvaccinated) who show no signs of this - which is why I'm leaning toward something that came from this particular seller.