My 6 month old kitten Marley breathes very heavy at times when he is sleeping on me. Is that normal or something I should be worried about? He was just at the vet on Friday for an upper respitory infection, but the vet checked his heart and lungs and said they both sounded fine. I have just noticed the heavy breathing, but he could have been doing it before and I just didn't notice. He was also diagnoised with Coccidiosis today as well. Could that cause him to breath heavy. Like I said he only does this while sleeping and only some of the time. Has anyone had experience with this?