Feline bronchitis, commonly called feline asthma, is a disease in cats affecting the smaller airways that branch off the windpipe (trachea). These branches, called bronchi, allow the transport of air into and out of the lungs. When the bronchi become obstructed because of constriction or con-traction of the muscles in the walls of these airways, the inflammation or irritation of the airways, or excessive secretions that plug the insides of the airways, the end result is an impaired ability to bring oxygen into the lungs for delivery to the rest of the body. Although the term "asthma" is commonly used to describe this syndrome in cats, this term is somewhat misleading.

Asthma, in people, specifically refers to the reversible constriction of muscles in the walls of the bronchi. Some cats have true asthma, whereas others have bronchitis. Bronchitis is associated with inflammation and swelling of the walls of the bronchi that cause a narrowed passageway and airway obstruction by plugs of mucus or other secretions, which also narrows these tubes.

Bronchitis can be acute (short duration) and associated with reversible changes in the structure of the airways or chronic (long duration, usually more than 2 to 3 months) and associated with permanent, irreversible changes in the airways.

Bronchitis and asthma can occur at the same time and can be caused by bacterial infections, parasites, allergies, or inhaled irritants; in many cases, the underlying cause cannot be found.

The most common signs of bronchitis in cats include constant, cyclic, or seasonal coughing; difficulty breathing; and/or wheezing. Episodes of coughing can mimic vomiting; some owners think their cats are vomiting up hairballs when they are truly having a coughing fit followed by retching. Breathing may be rapid or require excessive effort; some severely affected cats may breathe with their mouths open.

If your cat ever displays any of these symptoms, it should be promptly taken to your veterinarian for further evaluation, as these signs are a warning of potentially serious disease. These signs are not specific for bronchitis and can also be seen with many other diseases including heart failure, pneumonia, and lung cancer.

In the diagnosis of feline bronchitis by your veterinarian, the first test is usually to take a radiograph (x-ray) of the chest.

Second, your veterinarian may recommend obtaining a sample of cells from the trachea and bronchi to examine under a microscope and to culture for any infectious organisms.

It is also common to check the blood and feces for parasites (heartworm and lung worm, respectively). There are several principles to follow in the treatment of feline bronchitis.

First, any underlying disease (for example, bacterial or parasitic infection) must be appropriately diagnosed and treated.

Second, changes must be made in the cat's environment, since cats with bronchitis often have sensitive, hyperactive airways, and inhalation of irritating particles from the environment can cause worsening of their disease. Consequently, it is strongly recommended that their exposure to smoke (cigarette or fireplace), dusts (cat litter, carpet fresheners, flea powder), and sprays (insecticides, hair spray, perfumes, and cleaning products) be eliminated or minimized.

Third, weight reduction in obese cats should be attempted under the supervision of a veterinarian. Finally, medication should be given to treat the airway obstruction directly.

Two classes of drugs are commonly prescribed: steroids (such as prednisone, dexamethasone, and methlyprednisone), and bronchodilators (such as theophylline, aminophylline, and terbutaline).

Bronchodilators help to dilate or open the airways by relaxing the muscular walls. Common side effects of bronchodilators in cats can include gastrointestinal upset, restlessness, and lethargy.

Steroids decreases the inflammation and swelling of the airway walls. Side effects in cats are uncommon but may include behavioral changes.

It is important that your cat have regular rechecks with your veterinarian, as the doses of the medications commonly need to be adjusted. Prognosis is variable for this disease. If the underlying cause can be identified and successfully treated or eliminated, the prognosis is excellent. If permanent damage to the airways has occurred, the disease cannot be cured. With proper medical management, clinical signs can be controlled and the damage to the bronchi can be stopped or slowed.

Some cats suffering severe asthma attacks can die despite intensive medical efforts.

The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.

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From the Textbook of Veterinary Internal Information: Client Information Series. Copyright © 2000 by W.B. Saunders Company. All rights reserved.

Linda Mar Veterinary Hospital and its cat-only affiliate, Coastal Cat Clinic, are small animal practices located in Pacifica, California. To find a veterinarian or to learn more about the vet clinic and our staff, visit:[http://lindamarvet.com/]