I had one of my 2 year old hens gradually become more and more lethargic about four weeks ago. Diarrhea, sleeping all day, off feed, and closing/squinting one eye. I started the whole flock on Tetroxy HCA (only antibiotic my feed store carries) and electrolytes, but her condition continued to deteriorate and she died after about a week. The other birds remained healthy. This week a second hen is now sick (minus the squinty eye) with all the same symptoms. I am at a loss and ready to cull her and my one remaining healthy hen (don't want to keep a lone hen and can't give her away because she could be infected). These girls have lots of space, good food, and until recently were very healthy. Anyone have any ideas or advice? I thought infectious disease was rarely fatal in healthy adult birds, and I have no idea what they are getting sick from. Really sad to lose my whole little flock like this.