HI, I have 8 chickens that recently had an upper respitory infection. I treated the chickens with duramycin -10 for seven days and keep them isolated in the hen house. I also cleaned and sanitized the house and feeders. I also installed a heat lamp to keep them warm at night. The days have been plenty warm so no lamp during the day. Two of my girls were treated with daily shots of Tylan 50 as they were much worse then the others, and I had feared I might loose them. Everyone is much better, after the full treatment of antibiotics, except for one Australope. She is still having a bit of trouble breathing and has lost her voice. I have continued to give her VetRx orally and applied it under her wings and on her beak at night. My question is, is it normal for hens to loose there voice after this type of illness or could this be a different issue all together? She is eating, eyes and nose are clear and she is energetic, just no voice? Poop looks normal as well.