I spent all last summer cleaning dirty butts. They were clean from end Sept to end Jan and now they're dirty again. Not all of them, but several. They were all vaccinated by the hatchery. My question is, could dirty butts be a mild case of cocci? I don't see how, but I've wormed, dusted them all for mites, cleaned the coop and waterers/feeders, put a 2" layer of sand in the entire pen and do my best to keep things clean (can't do much with all this rain, but I try). What in the world can be causing this chronic dirty butt? I had a fecal done last fall and there were tapeworms, I successfully treated (even tho you never get 100% clear of parasites), everyone got the correct dose by weight and again in 7 days, then again in another 7 days. I'm at a loss. Maybe just wash and trim the feathers and keep them trimmed? The poop boards don't show messy poops except the periodic intestinal lining ones. My coop is 8 X 12 for 9 hens and 1 roo, the chicken yard is probably 50' x 50', so should be plenty big.