I have a 2 year old Barred Rock hen with what I believe is an upper respiratory infection, but I've had zero experience with that type of illness in my flock. She showed no signs of illness until day before yesterday (Tuesday morning) my DH came in and said she didn't seem as perky as usual and she seemed to be favoring one of her eyes. He immediately thought injury, I immediately thought infection. Her left eye had a slightly puffy ring around it, but no nasal drainage or other symptoms besides slight lethargy. So we quarantined her and I began to look for solutions. I decided to put her on Tylan 50 if I could find it, Duramycin 10 if I couldn't find Tylan. The local co-op only carried Tylan 200 & was out of Duramycin 10. The woman working the counter asked me what I needed it for & when I told her she said they'd been selling out of the Duramycin 10 for chickens because something was going around Anyway, I ended up finding Tylan 50 at a TSC. By the time I got home with it later that afternoon, her bad eye was really swollen (almost shut) and she had clear nasal discharge on that same side. I treated her with 1/2ml Tylan 50 injectable given orally at 3pm and again at 11:30pm (Tuesday - Day 1). The next day (yesterday - Day 2) she received 3/4ml at 8:30am & 8:30pm. This morning (Day 3) I gave her 3/4ml at 8:30am. In addition to her regular food/water (which she seems to be eating), she's also been getting plain Greek yogurt, crumbled boiled egg, and a few meal worms. We plan to treat with the Tylan orally twice a day for 5 days total. The swelling around her eye has improved quite a lot and her eye is fully open. Her breathing sounds like a percolator and she still has some clear nasal discharge, but she's eating good and pooping normally from what I can tell. She didn't lay yesterday or today. So my question is, how long do these things last? How much improvement should I be seeing with the Tylan after 5 doses (2 days) or should I try something else? I read a lot of forum posts about Tylan 50 and got a lot of differing info about dosing... Once a day, twice a day, 1/2ml for full grown LF hen, 1ml for full grown LF hen... I've just never dealt with anything like this before and I want to make sure I'm not missing something and I'm giving her the best opportunity for recovery. If anyone has any advice or experience with this type of illness, any information would be appreciated. Thankfully, nobody else seems to be showing any signs of illness at this time.