Watching the rate of breathing is one of the simple observations that you can make on a pet cat at home. This cat has a problem known as "tachypnoea", which means rapid breathing. IF you watch her side carefully, you'll notice that her sides are moving much more quickly than a normal cat at rest. Her problem is being investigated, so the precise cause is under review, but it's most likely that she has "hyperthyroidism", caused by a benign tumour on her thyroid gland