A couple of days ago my hens started with a gurgling sounding cough. Now the entire flock has the same symptoms. They are still active, eating, and have normal behavior . However tonight, I noticed bubbles in some of their eyes. I was hoping this would just pass, but now it seems to be getting worse. What are you supposed to use to treat respiratory illness in my backyard flock of 30 in Ontario, and where do it get it? ( Ontario doesn't allow antibodics to be sold at farm supply stores. ) TIA