I've had a self-sustaining flock for several years with a strict no bird in/no bird out rule. We've dealt with some health issues over the years, but nothing like this. My flock seems to be pretty hearty. Earlier in the summer, a snake got all of our chicks that we'd just hatched. In a moment of panic, I bought 3 20 wk old pullets from a NPIP certified farm. My friend bought 3 also. She integrated after 3 wks., 1 of her *new* ones got sick- lethargic, had what she described as pasty butt and died within 48 hrs of symptom onset. I still hadn't integrated mine yet, but mine didn't have those symptoms so I integrated mine. Her other 2 got lethargic, so they culled them. My birds seemed to be fine, until 8 days after integration. Mine are having different symptoms. Some of my older birds started having "bubbly discharge" in their eyes Thursday night. I haven't done testing, but based on symptoms, I am sure we are dealing with mycoplasma gallisepticum. I began treating with oxytetracycline in their water, yesterday, and 3 hens were then having nasal discharge- 1 being one of the young new ones. These are my 2 options, right now. 1) I can still save the flock. I have 2 broody hens, 1 with 3 babies, and 1 on 4 eggs that are supposed to hatch in 4 days, and they have never been in contact with the new hens. I can cull the rest of my flock and be MG free moving forward with two 3 yr old hens and their offspring. (My hubby isn't thrilled with this idea, not being convinced that they haven't accidentally been exposed, which I have read is thru shared waterers, exposure to infected nasal secretions, etc) We ofcourse feed and water the young first, and they are up in boxes, so we aren't walking in their area with shoes. We can clean out the coop and let the chicken run 'rest' for awhile. If I am going to cull and practically start over, I'd rather do it now than later. 2) Deal with the MG- treating when symptoms flair up during times of stress, have reduced food efficiency, egg production & egg viability. But will always have it. Death rates are low, but sickness is high. I have read a few places that some birds can build up a tolerance to it. There is the possibility that some of my birds may never have symptoms, but it will always be present. What are your thoughts?