My six month old Black Australorp (Pearl) suddenly died yesterday. She seemed fine the day before, although I noticed her comb looked pale but she had just laid an egg so I attributed it to that. The next morning she wasn't talking to me when I let the hens out of the coop as usual and she just sat and panted so I took her in the house and she passed within the hour. I took her to the avian vet for a necropsy. She bleed to death from fatty liver hemorrhagic syndrome. The vet said this is very common in pet chickens. Turns out our little, sleek Pearl was obese. We had no clue. The rest of the girls are now on a diet. As an aside, I've tortured myself over worming, should I, shouldn't I. I never have. She had no parasites.