I have what seems to be a respiratory issue affecting a few chickens in my flock and I have no idea what it could be.
We have 8 hens, and 1 rooster, all of which we've had for years; some for several years, others for just a couple. In that time all have been very normal and healthy, with no major issues.
2 years ago we bought two salmon faverolle hens from the same farm (I assume they were sisters). One was 100% fine and healthy, the other one we discovered, after having her for a couple weeks, was a little off. She started getting very sneezy, and we noticed that you could hear a sound when she breathed, like it was snotty or congested. She also always acted a bit differently from the other chickens, just kind of submissive and dopey. She has a great appetite and does everything the other chickens do, she's just a little different. Also, once in a while her eyes will crust up in the morning, in which case I would put a warm compress on them and they would open back up almost immediately. But that actually hasn't happened for a long time.
So after having this hen for months and months, and not seeing these symptoms spread through the flock at all, we assumed that she was not contagious. We have had her for about 2 years and there has been NO worsening in symptoms, no chickens have died, and until just a few months ago, NONE of our other chickens had any symptoms whatsoever.
About 3-4 months ago, I noticed that her sister seemed to be sneezing more, and was making a similar sound when she breathed. And now our rooster sounds like he has a frog in his throat when he tries to crow; he sounds very weird. I have no idea if these things are related, but I'm going to assume they are.
Other than the symptoms I mentioned, they are all completely healthy seeming. They're eating well, drinking, laying eggs, tearing up our yard, and doing all the other normal things that free range chickens do. They seem completely normal. And the other 6 hens have no symptoms at all.
I don't understand how if our salmon faverolle hen had something contagious, it could take two years for it to affect anyone else in the flock!
What could be going on??