Thank you for all the specific questions--answers to which I should have included in the first post!
She is not vaccinated that I know of but I doubt it could be Marek's since none of her four flockmates has shown any symptoms and I understand Marek's to be highly contagious. Plus, these five...
We have a lovely, sweet Austrolorp, just about 3 years old, who started limping six weeks ago. I thought she'd broken her leg or dislocated it. Then she got very sick, breathing hard and unable to eat much. I took her to a vet who x-rayed her and found no problems with her skeleton. Another vet...