We nearly lost our Ol to asthma last year
he developed it around the time we moved, and they reckoned it was trggered either by an allergy or an infection
It responded a bit to steroids, but best to antibiotics, with about a 5 week gap between attacks - which were life-threatening. He got very mopey, lethargic and fat.
It got worse and he responded less to the treatment, and it culminated in a trip to cat hospital for a battery of tests. That cost £700, found
nothing and triggered a
really bad attack that they couldn't fix. We were given the "well, he's had a good innings" talk and they tried one last completely off-the-wall treatment which was a
mycoplasma-specific antibiotic. injections every day for 10 days.
And that fixed him
Within 2 weeks he was thin, happy and active again and he's been right as rain for 9 months now.