Gerty, my RIR hen died yesterday suddenly after a few days of listlessness, weakness, white eggy diarrhea, loss of appetite and egg production, closed eyes, and low temp. she had been sleeping and not moving all day. when i try to make her stand, she couldn't and would fall, like there was no strength in her legs. so i put her in our portable cage and put her in my room for the night so she would stay extra warm and so i could watch her. when i left her for a few minutes, them came back to my room, she was spazing out, twisting her neck around, flopping, flapping wings and shaking. i picked her up and them she slowly feel limp, then her eyes closed. i could only hold her for a few minutes before her body started the rigor mortis (stiffening of the body after death). so if this happens to you, i am so so so sorry for you and the chook. but if your chicken dies for no apparent reason of from some virus or disease you must immediately take these cautions:
--place body in a box, wrap body to so you don't have to touch it. then if you want to bury it, place it at least two feet under ground so it wont be dug up by preying animals, so, also bury it away from your chickens incase it is dug up.
--sterilize coop by squirting hydrogen-peroxide/water on all poop stained (non-dirt) areas. scrub, then rinse with water. do the same to all feeders, or at least all the water bowls.
--rake run of poop and empty away from all gardens and animals. don't put poop in compost, because it may contain the disease in feces.
--give all your chickens (that have been around the diseased chickens) antibiotics, ask a chickens expert you know or vet
-- apple cider vinegar (1/4 cup for every 4 cups or more water, so its not too bitter), fresh water, fresh antioxidant fruits and veggies will help boost your chickens' immune system
