Obstructive and allergic lung diseases affect many cats and are sometimes called "asthma," "bronchitis," or "bronchial asthma." Unfortunately, these diseases are not easily classified and probably represent a variety of lung disorders. They do share a common finding of "hyper-responsive" (over-reactive) airways.
When the airway of the cat is sensitive to certain stimuli, exposure to these agents leads to narrowing of the airways. The inciting agents are usually direct irritants to the airways or things which provoke an allergic response in the respiratory tract. Regardless of the cause, the end-result is the same: muscle spasms in the bronchi (breathing tubes), buildup of mucus, and accumulation of cellular material. In particular, the inability to clear the bronchi of this material leaves the cat susceptible to secondary infections.
The cat is most stressed during the period of expiration (forcing air out of the lungs). The difficulty with expiration is typical with obstructive disease of the lung. Air may become effectively trapped in the lungs, causing them to overinflate. In some cases, this trapping leads to development of emphysema in the cat.
Are some cats more likely to get asthma?
Obstructive lung disease is most common in cats from two to eight years of age. The Siamese breed seems more susceptible. Also, some reports indicate that it is more common in female cats.
What are the clinical signs?
Coughing and respiratory distress are the most commonly reported signs with obstructive lung disease. Coughing is a significant finding since there are relatively few causes of cough in the cat. Also, many cats assume a squatting position with the neck extending during these coughing episodes. Wheezing is easily heard with the stethoscope and is sometimes so loud that it can be heard by the owners. Occasionally, sneezing and vomiting are noted.
What causes asthma?
As mentioned above, this group of diseases is characterized by hyper-responsive airways. The small breathing tubes (bronchi and bronchioles) can react to a number of stimuli, such as:
How is asthma diagnosed?
Several tests may be performed to achieve a diagnosis of allergic lung disease in the cat.
In some cases, an underlying cause cannot be identified, despite a thorough diagnostic workup. Even when the underlying cause is not identified, many cats can achieve a reasonable quality of life with medical management.
Some owners decline the complete workup for a variety of reasons. In such cases, it may be acceptable to treat the cat with a course of corticosteroids ("cortisone" or "steroids") since most asthmatic cats respond very favorably to these medications without side-effects. However, this approach may create two problems. Corticosteroids can complicate the management of cats harboring secondary bacterial infections; therefore, prophylactic antibiotics are reasonable in cases where a workup cannot be performed. Cats with heartworms often cough like cats with asthma and will respond temporarily to corticosteroids. Therefore, cats with heartworms may be misdiagnosed as having asthma.
How is asthma treated?
Successful management of allergic lung disease employs several therapies.
Will my cat recover?
Cats with obstructive lung disease are usually manageable. Sometimes "cure" may be achieved if a specific underlying cause can be identified and treated.
Extreme respiratory distress constitutes an emergency and the cat should receive immediate attention.
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