I'm not sure what to do. I first noticed that some of my chickens were sneezing and had runny poo about three months ago. I treated them with Terramycin for 10 days. That didn't seem to fix the problem. Then last week found out that they were infested with Northern Fowl Mites. (We looked at it under a microscope) LOL!! I found an egg with mites crawling on it after the hen layed and then I looked at her vent. GROSS!! It was bad. Can mites cause sneezing and runny poo? Should I wash the vents of the chickens that are really bad? I treated the coop and chickens with Sevin and put new bedding and nesting material down and sprinkled Sevin under the new shavings, in the nest boxes, on the roosts and in the corners of the coop. Question #1 Can mites cause sneezing and runny poo? Question #2 Should I wash the vents of the chickens that are really bad? Question #3 Is it possible that my chickens have worms? You are all wonderful. I'm so glad I found this site!!!!