Hi all! I'm pretty new here, and in the past four weeks I've had chickens, I've learned a lot! I have one 2-year-old bantam frizzle rooster, as well as five silver laced wyandotte chicks (three confirmed pullets and one confirmed cockerel) that are about 1.5 weeks old. One of the wyandotte pullets is breathing a bit heavier than usual, her cheeks and throat expanding noticeably when she does, and a smacking sound (like mucous) when she inhales. A few days ago, I started taking the chicks out of their brooder in the morning and letting them run around in the rooster's pen while he free ranges. The rooster had similar symptoms when he came home, but he was a rescue with scaly leg mites, poultry lice, ingrown spurs, and twisted toes. I got the chicks two weeks after I got him so that he would have time to be treated and recover (he's happy as can be without lice and with his mites receding!) without putting the babies at too much risk. I have a couple of suspicions; 1) The dust/hay in the environment is bothering them (I have horses as well) 2) There are new germs that the chick's immune system is learning about. Any thoughts on what it could be? I'm leaning towards the latter, so tomorrow I'm planning to give everyone a little bit of yogurt (for use as a probiotic) for good measure.