Just a note, that I did not receive a mycoplasma diagnosis, but rather talked to other experienced chicken owners and did some online research. My experience with Denagard has been very positive. I dosed at 16 ml per gallon of water for 5 days. Total birds treated : 16 . Not all showed symptoms of upper respiratory, but most had at least a sneeze. Some had coughing. Four had sneezing, rattly breathing, and one had that in addition to very swollen nasal passages around the eyes with yellow discharge. Everyone is now completely healthy. My two barred rocks that have had the rattly breathing for since July are now breathing normally. They're starting to cluck like chickens, something they didn't do before and I just didn't notice until they started. My barred rock rooster is starting to actually act like a rooster now, being a little cocky. MY other rooster who had a sudden onset of swollen nasal passages combined with yellow discharge that stained his white chest is doing just dandy. I also believe the mycosplasma prevented my barred rock from laying. Now that she's better, she's started laying eggs for the first time since we we brought her home. It cost about $55.00 for the product and shipping, and we have plenty left over. We'll use it monthly as a preventative as we bring in meat roosters from outside sources. For me, the cost was worth it because administering it was SIMPLE and we have so much left over. I'm so grateful to backyardchickens as I learned about Denagard from different threads on here. I hope someone finds this review informative.