Feline asthma is a common ailment among cats. An allergen, inhaled into
the cat's lungs, causes the smooth muscles around the airway to suddenly
constrict, causing difficulty breathing. 
While the specific allergens
vary from one cat to another, common allergens include tree and grass pollens,
cat
litter dust, cigarette smoke, and common sprays such as deodorants, hair
spray, room deodorizers, or
flea treatment products. It is often difficult or even impossible to
determine which specific allergens may trigger a reaction in a cat.
Feline asthma afflicts about 1% of the general adult cat population, and is found in cats of all ages and in all parts of the world. Cats with feline asthma generally display symptoms such as coughing and wheezing. The cough is usually a dry, hacking cough and is sometimes confused with the sound of a cat with hairballs.
In order to properly diagnose a cat with feline asthma several tests must be completed. These include a chest x-ray, a feline heartworm test, a complete blood count, and a sample of cells from the cat's lower airway. This sample may be obtained through techniques such as bronchial wash, Tran tracheal wash, or bronchoalveolar lavage.
Feline asthma is not curable, but it is treatable. When properly diagnosed and treated, many cats with feline asthma suffer far fewer symptoms. Unfortunately, feline asthma is also a progressive disease and symptoms generally continue to worsen over time. The most effective treatments tend to be inhalers similar to those used by humans with asthma. These inhalers need to be specially tailored to be used with cats, usually by adding a mask and spacers to the inhaler.
A corticosteroid is the most commonly prescribed drug for feline asthma. This
acts as an anti-inflammatory agent, helping to reduce the chronic swelling in
the airways that feline asthma commonly causes. Bronchodilators may also be
prescribed. 
These help to open the airway during coughing or wheezing
attacks. Some cats do not respond to inhalers alone and require additional oral
medications. Generally, inhaled medications are thought to be more effective
against feline asthma and are normally preferred by veterinarians.
While it may be difficult or even impossible to identify the specific allergens that trigger your cat's feline asthma, reducing common allergens in the environment may have a positive impact. Smoke from fireplaces and cigars or cigarettes tend to settle down near the floor, putting it directly in the cat's immediate area. Reducing exposure to smoke can help reduce asthma symptoms. Using a low-dust clay cat litter or switching to a non-clay formula can also help your asthmatic cat's symptoms.
