It started with a silkie hen. I went out a couple mornings ago and found all the other chickens awake and waiting for breakfast. She remained sleeping. I pet her, but she didn't move away. I thought it odd, but chocked it up to the storm over night. Maybe she hadn't gotten enough sleep because of it. I went out later and found her laying on her side on the ground. She was alive, but laying there stiff. So, I brought out a towel and wrapped her loosely for warmth, then put her in a kennel and brought her inside. She worked her way out of the towel and stood....but she was moving strangely. Rocking back and forth on her feet and shaking her head. After a minute, she tucked her head and went to sleep. ...And died in the middle of the night. This morning, I found yet another silkie moving strangely. He was hunched up, rocking on his feet. He turned in a circle once, and while I went for a kennel, he made his way to shelter, tucked his head and went to sleep. He now sits in a kennel, separated from the others. I suspect he will be dead by tomorrow morning, just like the hen. So the run down of symptoms is; sudden onset, odd movement or lack of balance, sleep, then death and if this one follows suit, death in 48 hours or less.