Hi, I am new to this group and this is my first post. Tonight as I locked my chicken coop I noticed one of my chickens had a very swollen, bald butt. The vent is not blocked from the outside, but the area below is soft and swollen to the size of a tennis ball. Most of the feathers below her vent are gone. She was active today and eating okay. I got an egg from her yesterday. She does not squawk when I touch the area, which is soft and ply-able, but I am not sure how she would react if it did hurt, so that does not tell me much. She was a little dirty around the butt.( it is the rainy season here in California) and I put her bottom in warm water to clean her off. She is in the house tonight and acting a bit agitated at the new surroundings, but other wise no distress. Anyone have a suggestion as to why her belly is so swollen and what I should do about it? Doris from Oakland Ca.