Hello-- I had posted earlier that I am currently treating my flock for coryza. I have two Polish hens that have severe symtoms, and have noticed minor symptoms in my 2 roos and one or two other hens. I have close to 30 birds of varying breeds. I do not free range because of heavy predation from stray dogs and coyotes but have a large henhouse and run. It is primarily the older birds that are affected. I currently have them on sulfamethoxine, with the two sickest birds segregated from the flock. I will be throughly disinifecting the henhouse and replacing the litter today. Prior to the repiratory infections I was wondering why I was only getting 2 eggs a day despite the girls being under supplemental lighting. Then I discovered lice on some of the hens. I believe this all started when I brought 3 new chickens from a fur and feather swap into my flock without quarantine. I read however that recovered birds will always be carriers which can then infect other birds even though they are seemingly healthy. So would quarantining have even mattered if they were asymptomatic carriers (though one did die within a week of purchase)? If this is the case, how can one ever add new birds to their flocks? Should I cull my sick birds even though they may recover? Ethically can I ever sell any of my birds knowing they were exposed? I am tempted to get rid of all but my favorites (even though I love them all!) And start over with all new birds in the spring. I have never culled, and I really don't want to either. My chickens have always been a pleasure to raise, but this is becoming a nightmare! Any advice would be greatly appreciated!