Only a vet can tell, and not with one test. Cornell's Feline Health Center says asthma affects between 1 and 5% of cats and that no single test proves it, so the vet first rules out the other causes of coughing and wheezing. A cat that breathes with its mouth open or struggles for air needs a vet now, whatever the cause.
Asthma is a disease of the lower airways of the lungs. Cornell says most vets and researchers agree it is an allergic reaction to particles the cat breathes in. The airways become irritated and swollen and tighten, mucus can build up, and air has trouble moving through.
Cornell puts the average age of the cats found to have it between 4 and 5 years, and sees no difference between males and females. The Merck Veterinary Manual says young cats and the Siamese and Himalayan breeds are most often affected, while Cornell says a Siamese link has not been definitively proven. A second Cornell page gives a lower count than 1 to 5%: about 1% of cats.
The suspected triggers Cornell lists are tobacco smoke, dusty cat litter, vapors from cleaning products and aerosol sprays, pollen, mold and mildew, dust mites, smoke from fireplaces and candles, and some foods.
Cornell's list is difficulty breathing, wheezing, rapid breathing, coughing or hacking, open-mouthed breathing and vomiting. During an attack many cats hunch close to the ground and stretch the neck forward. The signs range from a mild, long-running cough to a sudden crisis, and the Merck manual says they may come and go.
The cough is easy to take for a hairball. Cornell says a hairball every week or two is nothing to worry about, but that frequent hacking with no hairball may have nothing to do with hairballs and may be a sign of a serious breathing problem such as asthma. Film an episode on your phone and show it to the vet.
So the vet uses several tests and rules other diseases out.
| Test | What it looks at | What it tells the vet |
|---|---|---|
| Listening to the chest | Breathing sounds through a stethoscope. | Cornell says the vet uses it first, to find where the wheezing comes from and to look for heart or lung problems. |
| Chest x-rays | The airways and the size of the lungs. | Cornell says they often, but not always, show a bright branching pattern along the airways, and lungs that look too large because air is trapped. |
| Blood test | Eosinophils, white blood cells linked to allergy. | A high count fits an allergic cause. |
| Stool test | Lungworm, a parasite that can live in a cat's airways. | Whether a parasite is behind the cough. |
| Heartworm tests | An antigen test and an antibody test on blood. | The American Heartworm Society says heartworm in cats can cause attacks that look like asthma. |
| Bronchoscopy | A flexible camera passed into the airways under heavy sedation or general anesthesia, with cells collected from the lining. | Cornell says cells from an asthmatic cat's airways may show high numbers of inflammatory cells. |
| CT scan | A three-dimensional x-ray picture of the chest. | Cornell says it may help tell asthma from other airway diseases. |
A study in the Journal of Feline Medicine and Surgery compared 73 cats with asthma and 24 with chronic bronchitis at the University of Munich's small animal clinic, and found that no single sign, x-ray finding or blood result could tell the two apart. Coughing was reported in 95% of the asthmatic cats, 40% had a high eosinophil count, and 6% had normal x-rays.
Cornell names the look-alikes: chronic bronchitis, lungworm and other parasites in the lungs, and infections that cause pneumonia. Heart failure is another common cause of breathing trouble, and it is covered on What does heart disease mean for my cat? Petipedia also explains x-rays and ultrasound and the blood test.
Cornell says vets usually prescribe a corticosteroid, a steroid that reduces the inflammation in the lungs, with or without a bronchodilator, a medicine that opens the airways. Both come as pills, as injections and as inhalers. Cornell says a bronchodilator is usually not used on its own, because it does not treat the inflammation, and the Merck manual says the same.
Cornell calls the inhaler the ideal route, because more of the drug reaches the lungs. The drug is puffed into a small chamber called a spacer, which fits a mask held over the cat's face for about 10 seconds. Cornell also says frequent and long steroid treatment in cats is linked to a higher risk of pancreatitis, diabetes and other conditions.
The steroid on Petipedia's medication pages, prednisolone, has a label that says it is for dogs only. A vet can still prescribe it for a cat. The FDA says the law allows a use that is not on the label only on the order of a licensed vet who is treating the animal.
At home, the Merck manual says it is important to avoid sprays and things the cat may react to, such as cigarette smoke, perfumes, pollens, molds and dust. Cornell is more cautious: it says avoiding allergens and purifying indoor air help people with asthma but have not been rigorously tested or proven to work in cats. Keeping smoke and sprays away costs nothing, so start there, and be slower to pay for an air purifier or other extras. Cornell says allergy shots and omega-3 fatty acids show some promise but need more research. A review in the Journal of Feline Medicine and Surgery says antihistamines cannot be recommended as the only treatment.
Cornell says asthma is often a progressive condition that does not improve much over time, with flare-ups that range from mild to life threatening. A cat is never truly rid of it. But Cornell says owners who watch the cat's breathing effort, keep an eye out for coughing and step in with medication when it is needed can help their cats live happily for years.
None of these sources gives a price, so there is none here. Expect tests at the start, then medicine and rechecks for the long term. See what a vet bill costs, what to do when you cannot pay it and what pet insurance pays for.
Cornell says any cat showing signs of breathing difficulty, whatever the cause, is at high risk of dying if it is not treated promptly. Go now if your cat breathes with its mouth open, pants noisily, breathes noticeably fast, or holds its head low with its body stretched forward. The Merck manual adds bluish gums as a sign that the blood is short of oxygen.
Keep the cat calm, call the clinic to say you are coming, and see Cats: is this an emergency?
If something here is out of date, tell us at hello@petipedia.io and we fix it the same day.
Sources read on 2 October 2026; every number is as the source gives it. Three of the Cornell pages carry no date.