I have a golden comet normal in every way except I've heard a slight honking, almost like a croupy cough from her. The book that I have about raising chickens doesn't have info on this nor any other significant disease...and why is that these books that glamourize keeping backyard chickens fail to provide info on diseases and how to put a chicken down if need be? That kills me! If you are going to take on this responsibility, shouldn't these books tell you how to put them down quickly? I digress...any idea on the sound?
I would listen and see if any rattly breathing accompanies it. If you hear rattly breathing or you see sinus discharge, i would isolate to discover more. If it's just a honk, i wouldn't worry.
Mine did that for a couple of weeks, no other symptoms. I think she had a blade of grass or something stuck in her crop. She's fine now. Give it a little time, she may just have something in there, that will pass eventually.
Has it rained in your area recently? I found a few of my girls have the honk after a hard rain, because the water mixes with the ammonia in their poop and irritates them. I keep a pretty clean coop and run, but I can't be out there 24/7! If this is the case, it should go away in a day or so. Keep in mind, chickens have different 'voices' and can honk more often than others. As for culling, I can't help you there.
