Today I was petting my 16 year old cat with CRF and realized that he should be purring. He had been sitting on my lap for 20 minutes while I was watching TV and when I turned it off I noticed that something was missing. He wasn't purring. Then I realized I don't remember the last time he purred. It also sounds like wheezing or watery breathing through a straw? Could it just be a cold or allergies. He was just at the vet and was doing well. Has anyone elses cat ever stopped purring? What could it be?