I've lost 4 silky chickens out of 12. The symptoms sound like Marek's but they are less than one month old i.e. seem slow, then sleepy, eyes close, wing edges tattered, then die. They are with their hen, but separate from the 'flock'. Can you give me an idea of what it might be/treatment or do I need to take a corpse to the vet? Thanks for your help (I hope).