I've got a hen that I've noticed panting for the past 3 days. No other chickens are. It's been hot, so I thought maybe she was just hot. Made sure they had fresh water and moved on. After noticing her panting while none of the others are, I decided to check her out. She seems to be acting normally in every other way. Fresh water is readily available. I waited until tonight when the temperature had finally dropped into the 70's and she is still panting. I've put some ACV in the water. She's not showing any other signs of illness at the moment, but using that much energy to breath fast can't be good. Any ideas?