I've looked elsewhere, but could find nothing noting this individual symptom. We had an older Buff -O hen (pretty sure she'd quit laying) who had a dirty, scraggly posterior, a condition that lasted for about a year. I'd wash her off occasionally (when I could catch her) but the condition would only return. No other members of our flock exhibited this. There were occasionally runny stools in the barnyard from some bird, but I could not determine which. No changes in appetite or behavior from that particular hen. She was about 4 - 5 years and just HUGE!. I thought Cocci and was going to treat her individually, but was unable to confirm. She passed on a day or so ago. Not sure why she passed, but likely related to her ailment. I feel badly that I didnt' treat her as I didn't want her to suffer, but she was pretty much a convelescence case, so I was going to retire her this fall anyway. We're pretty poor. I now have one year old hen who is showing the same thing. What can it be please? If Cocci, the instructions on the bottle of medicine (sulpha?) says I can not collect or eat, (or certainly sell) eggs after treatment to the flocks drinking water, but it does not say for how long (- a reason I resisted treating the entire flock).