One of our chicks, a Sebright, has had what appears to be a respiratory issue for over a week. I've tried nearly every remedy I've found on BYC forums and while its condition has stabilized, it's not getting better. It eats and drinks, but is lethargic, opens and closes its beak in an odd way (sorry not to be more specific, but it seems to be gasping for air), and its feathers look ruffled and scruffy. Last week the other Sebright had to be culled because of Marek's symptoms. This one doesn't have the same set of symptoms and isn't paralyzed. My question is: how long do you let your chickens recover before culling them? Thanks for any advice! A friend can cull it tonight, but won't be back in town for at least a week.