Yesterday, I let my 7 birds out of the coop for some free range time. I didn't notice anything out of the ordinary. They all came running out and followed me around the yard for a while before going about their business. About 2 hours after dark, I went to the coop to lock up for the night and noticed my Silver Laced Wyandotte was not inside. I looked all over, and found her lying under my deck, legs under her, head tucked to the side. I picked her up and carried her back to the coop and placed her on the ground. She was flapping her wings fairly strong when I handled her, but unable, or unwilling to walk. She would just kind of tump over falling forward. There was no other signs of illness. Nothing appeared wrong with her eyes, and no coughing, or drainage from her nostrils. I was not able to observe her poop. Any ideas what could be wrong. I know a lot will say Merek's, but she has been very healthy and laying well and showed no signs of any weird leg movement or paralysis. It seems whatever happened was very acute, coming on suddenly. She is about 21 months old. I put her in a makeshift coop with some hay, and this morning she was dead.
Any ideas wha cold have happened? I am wondering if maybe she was egg bound and I missed it, or maybe a Copperhead bit her? Who knows.