1) What type of bird , age and weight (does the chicken seem or feel lighter or thinner than the others.) She's an ISA brown and is either 2-1/2 yrs old or 4-1/2 yrs old. (Two batches and they all look alike.) She has rapidly become larger than the other hens. It's not just feathers, she feels larger too. 2) What is the behavior, exactly. She's willing to eat but gets around much more slowly than the others. Walk has changed to more like a waddle than a natural chicken gait. Even for an ISA brown, she's very passive. Last night she did not go up to the roost but stayed down in the bedding. 3) How long has the bird been exhibiting symptoms? About three days. 4) Are other birds exhibiting the same symptoms? No 5) Is there any bleeding, injury, broken bones or other sign of trauma. No 6) What happened, if anything that you know of, that may have caused the situation. Nothing apparent. 7) What has the bird been eating and drinking, if at all. Layer mash. Water. Scratch when the weather is cold. The chickens are out of the coop for several hours every day and have free run of the front yard. 8) How does the poop look? Normal? Bloody? Runny? etc. Appears normal. The egg channel looks pink and healthy -- no mucus or foreign matter. 9) What has been the treatment you have administered so far? Worry. 12) Describe the housing/bedding in use They have a two level coop with nesting boxes on the higher level. Wood shavings for bedding. Does anyone have a suggestion as to what to try?