I have a flock of 25 chickens. Different ages ranging from 6 weeks old to 2.5 yr old. Mostly hens. When I am in the yard I hear lots of sneezing, snorting and there has been a BIG drop off in eggs. Out of 8 layers I am getting 1 or maybe 2 a day. I have 2 others that are with eggs or chicks. Last year I have a round of CDR with some of the hens and thought that they would not get sick anymore. Do you think that the heat has brought it back???? I am going to start them on Lincomycin-Spectinomycin again like I did last year. If it is the heat I would guess it will happen every year???? THey have lots of shade and a automatic waterer and I spray their "bath" area with water mid day. I just want my chickens to be better.