We lost one of 9 white Leghorns yesterday without warning. Another just now found dead in her house. A third is showing symptoms of lethargy and no appetite. Hubby did notice very runny poo in the coop. Nothing has changed regarding food, water, etc. Hens are about 16 months old. We got them from Myer Hatchery when they were 1 day old. What's going on? What can we do or treat them with? Is it viral, bacterial or parasites? It is hot here in Alabama, but they have a large, roomy coop that's under huge shade trees. They don't free-range, but do have a large coop with room to run.