We bought eight chicks about a month ago. They were all the same size when we got them. The leghorn is now twice the size of the other chicks. It's legs are fatter than my hens (Rhode Island Reds) that I have had for two years. Her legs are literally huge. She refuses to perch to the point she has worn the feathers off of her underside. She refuses to stand as well. if you make her stand she will stand for a few minutes max and then she is sitting back down. She sits to eat and drink. Is this Marek's disease that I have been reading about? Since my other hens are in a coop beside them, are they now infected? Am I going to lose my entire flock????