I have two hens that are around 3 years old that are not even kept in same area together (one resides in coop) and the other resides full time in my barn and roams the back yard. They both have mysteriously come down with somewhat similar symptoms.. the one being a bit worse than the other.. both have the clear bubble like froth in their eyes.. the hen in the barn is worse.. the hen in the barn had a crusty dried substance over part of her nostril.. not sure if it was discharge or actual mud/food build up.. but I cleaned it off tonight and noticed a smell to it/her.. not really describable.. just an off odor. the other hen has no nasal discharge.. both are eating and acting for the most part normal.. somewhat not as active but still clucking around and acting like chickens. I have a flock of various other hens and roosters and noone else is displaying this so far.. there have been no changes to my practice. no new birds, no visitors, no food changes, weather has remained same.. mostly warmer (NE Ohio).. cleaned areas out quite a while back.. so they are in far cleaner areas than during winter build up.. plus they are out roaming all day.. I do notice what seems to be some sneezing and head shaking from both hens also. as stated they both seem to be eating.. not sure if it as much as normal but are eating.. drinking too. the one hen I noticed that her poop output seems smaller.. she is a buckeye hen and her poop would be similar in size to small bird turds.. could be if her eating has declined. anyway wondering what to do.. not sure what or how they could have even caught something.. but I would rather be on safe side..