Originally Posted by Pyxis
The feather loss can be indicative of mites, so I'd dust her and the flock for them. It can also be a sign of bullying. I would split her away from the main group for now if you haven't and provide her with her own food and water. The other thing the feather loss could indicate is over-mating - do you have a rooster? If so check her sides and under her wings for wounds. Roosters can accidentally injure hens with their spurs and they can leave some nasty puncture wounds. Is she having any trouble breathing? How is her poop? Diarrhea is a common symptom of coccidiosis so look for that. Also look for blood in the poop. If she does have it you'll want to treat the whole flock for it because it spreads.
But I agree with horsekeeper that it sounds like a really quick onset for a disease, so I'd look for other things it could be too.
Originally Posted by MorrisRdFarms
The symptoms that I see are her wings drooping, not being able to stand without swaying or laying down, and her mouth hanging open. She is usually timid and scurries away, but tonight she didn't move and I was able to pick her right up. She has also started losing some feathers at the base of her bun tail. There are no other animals other than the 5 adult BO and 6 RSL pullets.
It's so hard to tell, but I have had to cull two turkey toms this year that were ganged up on and injured by the other toms bad enough that they were acting the same way. I already had too many toms so I put them in the freezer instead of trying to help them. I have culled some chicken hens as well that were injured either by breeding or other chickens ganging up. They either had back or leg injuries and the rest of the flock was relentless going after them. Same symptoms, difficulty walking, wings drooping, mouth open from pain (I assumed), and using wings like a crutch to walk with an obviously painful and crippling injury. Much kinder to cull to prevent further suffering.
I pressure cook old or "questionable" birds either to tenderize or destroy any organisms I worry about. I've discovered broken bones, dislocations and bad bruising while processing. One of the big toms had a shattered hip and I think he flew down from the tree or off the roost and smacked into something.