So it started with an adult hen, then spread through my flock before I had a chance to react. This respiratory infection. They sneeze and some have raspy breathing. I've been very careful about keeping the chicks separated, but eventually they caught it too. I've lost only one adult bird, but I'm loosing a chick every one to two days. Some gasp, some are raspy breathing. Some don't seem sick at all. I have the entire flock on antibiotics, but it is measured in Milligrams, and None of my scales go that low, so I've had to do some reverse calculations and some serious guessing on dos sage. I also removed all the litter and bleached everything down before replacing the birds back into their respective areas. So here is a question. Is it possible to OD a bird on antibiotics. Second, anything else I can do? I've never had a serious illness sweep through my flock like this before. I have had a history of Merrick's in my flock, but that only kills a bird for me once every couple of years. (I also disclose the Merrick's exposure to anyone who wants a bird from me.) I usually avoid antibiotics, since I breed for hardiness, and quick to cull a sick animal, but this moved so fast, and i knew without medication i would loose all those chicks in a matter of days, if not hours. This is day four of the antibiotics, the older birds seem to be better, only one hen is still having raspy breathing but she eats and drinks fine, no runny nose, no more sneezing. I am still loosing chicks on a rate of every other day. Any insight or suggestions would be greatly appreciated. PS could it be parasites? If so, what wormers are safe for chicks?