Respiratory rate?

My cat, Pie, is breathing funny. Something the vet noticed when he was diagnosed with an URI. He's seemed fine since recovering, but today he is open-mouth breathing some (not all the time). He is purring quite a bit, but doesn't seem to be in distress. Vet said before that he might have asthma. Can I count his respiratory rate while he is purring? It seems faster when he's purring.

Cats purr when they are comfortable and content, they also purr when they are in distress. Asthma in cats is very similar to that of humans and can be caused by several different things. You need to know what is causing it.

Heavy breathing is also an indication of other illnesses. some serious. I would take my cat to a vet to get a concrete diagnosis.