This may sound a strange question, but we had a cat who developed heart disease at 15 and despite everything we could do for her the vet after 6 months eventually suggested being kind and putting her to sleep.
We then adopted a bengal mix and he is nearly 4 and started to show similar symptoms like breathing heavily and sitting with his elbows up but my son did pick him up a couple of weeks ago and he twisted to get away and I sort of hoped he had just pulled a muscle or something, am not sure whether a cat can pull a muscle but the breathing lis getting ess heavy now. It is just that I read you should not be able to see a cat breath and before I take him to the vet wondered if anyone elses cat does this. The thought of 2 cats having heart disease is too sad to think about.