He could have airway issues or asthma issues. Mookie is similar. Even though he had his nares and palate done, he still gets wheezy. He is much worse on hot, bad air quality days. The palate is hard to diagnose, until they actually get in there. If they are having a hard time breathing, they can develop everted sacules. He could have a narrow airway or a collapsing larynx. The collapsing larynx is caused when they have been dealing with the other conditions and labouring to breathe. This site covers some of these issues
http://www.cavalierhealth.org/brachycephalic.htmWith Mookie, I would stop him from running, if he became wheezy. He also sounds like Darwin, when he breathes.