I just adopted my first Cornish X chicks from the TSC about 2 weeks ago. I didn't even think to quarantine them, I don't know why. So, in they went with some mutts I'd just hatched. A few days after I brought them home, the Cornish started showing signs of a respiratory illness: coughing, sneezing, wheezing. They're still eating and drinking like mad, of course. I have ACV with the mother in their water, and that seems to help their congestion. The main thing I've noticed is that my mutts are showing absolutely no symptoms and continue to breathe easy. So my question is: Do Cornish X have weaker immune systems than regular chickens? Just curious. Thanks in advance for any info on the subject!