Just some quick info on feline asthma. When the airway of a cat is sensitive to allergens, exposure to these agents can lead to narrowing of the airways. Some of the allergens that cause this response are the same ones that lead to problems in humans such as inhaled stimuli-- cat litter dust, smoke, pollens, molds, fungus, perfumes, and sprayed chemicals such as cleansers. Different viruses and bacteria may also cause a problem along with parasites such as lungworm and heartworm. Different times of the year may be worse for an asthmatic cat depending on what the trigger allergens may be (Jonas is worse in the fall, could be ragweed, the molds associated with fallen leaves, etc). The most common symptom of asthma in cats is coughing and respiratory distress. A lot of cats will assume a squatting position with the neck and head stretched forward while coughing. Accessory mucles in the stomach may be used during respiration, open mouth breathing is always a very serious sign and the cat should be seen immediately by a vet.
Vets use different diagnostic tests to check for asthma. They may do a complete blood workup, heartworm test, Feleuk and Aids test and chest xrays. They can also do a bronchoscopy (direct visual exam of the airway). Of course when your cat is in acute respiratory distress, they first stabilize the kitty and may then proceed with testing. Some owners may decline to have a lot of tests done and instead treat the cat conservatively with meds to see if kitty responds.
Meds used to treat the cat are a lot of the same meds used to treat people. Oral steroids and bronchodilators can be used as can inhaled steroids and bronchodilators. There is a special chamber and face mask (called the Aerocat) that is made specifically for use in cats. Jonas has one. It does take some getting used to for the cat as initially I found Jonas panicked and was uncomfortable with the mask placed over his face. It's so hard as we can't explain to them that this will make them feel better. My husband has COPD and he had told me that nothing in his life has felt scarier than the feeling of not being able to breathe. You don't like the feeling of anything placed over your face, though as a human we realize that the O2 mask is going to help us.
Some of the things you can do at home are the same things you do for anybody with asthma or allergies. Avoidance of anything known to trigger the problem. Jonas has his own room with a super HEPA filter air cleaner. There are no rugs in his room, I wash his bedding down often and don't use any aeorsol cleaners in his room. Any cleaning is done with him out of the room and I use a "green cleaner". Low dust cat litter is a must. A lot of these same things I was already doing because of my husband. When you think about it, it's really a good idea for all of us to be breathing in less chemicals, pollen and dust, whether we have allergies or not.
Asthma does not have to be a death sentence, it can be treated and managed. I do think it is on the uprise in cats, or maybe it is just being diagnosed more. Allergies and breathing difficulties is on the uprise in people so why should our pets be any different. Airtight houses may be good as far as saving on your energy bills but they can also cause problems. But them you wonder about the outside air---- I guess it's a case of damned if you do and damned if you don't!
Disclaimer: I am not a veterinarian; I am sharing my thoughts and experiences from my years of having pets. Information from me should never replace the advice of your pet's veterinarian.