I have two 8 week old RIRs and one started sneezing about 3 weeks ago and still is (I'm not sure if the second one is or not). It's really just a little "chew" sound, but quite she does it frequently like every few minutes. I see no other signs - no runny nose or anything. She is now in the coop along with four 5 week old chicks of various breeds - they've been together about 5 days now and I just noticed that some of the younger ones are now sneezing as well. They do it inside or out, although they're only out for short periods of time right now as the run still needs some work for me to leave them in it. I use purchased pine shavings that came in a bale on top of newspaper. I used this while they were inside (when the RIR first started sneezing) and now also in the coop outside (I still have a brooder lamp on at night for the young ones in the coop). The chicks were supposed to be vaccinated for both Marek's and Cocci. Any ideas?