Last year around this time one of my two hens (a now circa 7 year old hatchery EE) started sneezing a lot. She seemed to be a little worse at breathing, almost like she was "stuffed up," if you know what I mean. Everything else was normal. She doesn't produce a lot of eggs at her age anymore, but she does produce some. I kept an eye on it whilst I was home for Christmas, and it neither got better nor worse, so I thought something infectious was somewhat doubtful, instead thinking it to be an environmental thing I couldn't figure out. The other hen was entirely unaffected. When I last visited home in April, she seemed to have "recovered." I'm home for Christmas again, and my parents haven't said they've noticed anything off with this hen. The other hen has since passed away from what I suspect to be entirely unrelated causes, as there was no respiratory involvement and she pretty much just dropped dead. I've heard that's not uncommon after about 5 years or so with hatchery birds. So anyways, she's not sneezing a lot this time, but if you stand close enough to her and it's quiet you can hear breathing "clicking." Again, no other signs. I now suspect it's Chronic Respiratory Disease. My family certainly doesn't plan on getting any more chickens, so that's not an issue. My question is, should I take her to a vet? Should I get her antibiotics? It's so mild, my concern is if I medicate her every winter for the rest of her life it'll just result in antibiotic resistance, and I want to have the meds as an option in my "back pocket" in case it gets worse and I have to save her life. My family and I have been doing our best keeping the coop and run clean, but admittedly it's hard (poorly-designed coop; I now know for next time if I ever build another one).