Hey all this is a bit long but would love peoples thoughts an opinions When I first got chickens I purchased them from a local no-name feedstore. It was so run down and all the chicks were kept in fairly terrible conditions. Of course I had to save them! Fast forward to the chickens being about a year old, one of the Buff O. has a swollen face, my BR and RR hens also start exhibiting upper respiratory problems and bubbles in the eyes. I went to the internet to figure out what their illness may be and came to the conclusion it was Mycoplasma. They were in terrible shape and I was just about convinced they were going to die. But they all pulled through thanks to Tylan 50 sub-q injections, Vet-Rx, and my very patient husbands help. Weird thing though is that my Silkie rooster and Americana hen NEVER displayed any signs of illness. I did not segregate the sick hens at the time because I figured if they had Mycoplasma they would all have it and in the end wouldn't have helped. I've had the BR hen for close to three years now and she has never since exhibited any signs. She's been in extreme Mississippi heat, traveled across country, and experienced Oklahomas ice winters, so fairly high stress situations. To my understanding those times would have been perfect for a flare up. Additionally she has been mixed with other flocks and no one ever got sick. Is it possible they all just got some type of contagious upper respiratory infection that ran its course and went away? That I may have possibly miss-diagnosed?