Feline asthma is an inflammatory respiratory disease that appears very similar to the version of asthma we recognize in humans. It's considered a chronic or recurring condition in which the lining of the lungs' airways suffer inflammation and consequently constrict. This kind of asthmatic airway constriction can occur either spontaneously or secondary to an allergic reaction.
The exact cause of the disease is unknown but it's presumed to have a genetic origin. As such, feline asthma is recognized as a disease inherited with varying severity. Some affected cats can suffer severe airway constriction leading to acute respiratory distress and death while others experience a simple occasional cough.
Symptoms and Identification
Airway constriction typically leads to the following symptoms: shallow breathing (it's hard to take a deep breath when your airways are swollen), exercise intolerance, coughing (or hacking), wheezing (which can sometimes only be heard with a stethoscope) and/or the presence of abdominal effort while breathing (particularly upon exhalation). But not all cats will experience these symptoms at once. Indeed, most mildly affected animals display only a low-grade cough with none of the other symptoms present.
The symptoms can be present chronically or episodically so that some seemingly perfectly normal animals can even suffer acute respiratory compromise and sudden death as a result of one terribly severe event. Ultimately, the course of this disease is difficult to predict and, consequently, to diagnose.
Diagnosis is most often achieved on the basis of clinical signs, physical examination (which includes chest auscultation) and X-rays showing a characteristic pattern of chronic or acute airway compromise. The lungs of asthmatic patients will show evidence of being overly inflated (as the patient ties to draw more and more air into the lungs and it gets trapped there) and/or characteristic signs of airway inflammation (little bright "donuts" or parallel lines).
It's important to recognize that patients suffering acute respiratory difficulty can die during the diagnostic process (positioning for X-rays can be highly stressful to a cat that cannot breathe well), which is why sometimes empirical treatment precedes definitive diagnosis.
Another problem confounding diagnosis is that the lungs of cats who are currently not suffering an asthma "attack" commonly appear perfectly normal. That's why response to treatment and ruling out other conditions (like heartworm disease) is often the best approach to diagnosing feline asthma. Tracheal washes and bronchoscopy are two procedures that are commonly employed to help rule out other major diseases.
The disease itself is not treatable. It can, however, be managed with oral, injectable or inhaled drugs. The goal of these approaches is to relieve airway constriction. Preventing future episodes is a fundamental aspect of ongoing management of these cases.
Drug-wise, corticosteroids (like prednisone) are at the top of every veterinarian's list of the most effective, least costly approach to treatment. Corticoteroids, however, have to be administered long-term to feline asthma patients and, as such, their serious side effects have to be weighed against their benefits.
That's why inhalant drugs to reduce airway inflammation have become more popular in recent years. Bronchodilators and inhaled corticosteroids are far less side-effect fraught, though they do offer the down-side of greater expense and greater difficulty in delivery (many cats resent mask-type inhaler devises).
Other approaches include oral bronchodilators (like theophylline), oral cyproheptadine, antihistamines (like cetirizine or diphenhydramine), cyclosporine (marketed for pets as Atopica) and the human drug zamflurkast (Accolate), which is considered experimental in cats.
Diagnosis and treatment can be very inexpensive or it can very quickly run into the thousands of dollars. It all depends on how severely the patient is affected and how carefully we choose to make a diagnosis. Typically, the expense of asthma comes down to whether owners can afford to rule out other diseases or try safer drug alternatives. At a minimum, owners should expect to shoulder at least $250 for a basic diagnosis and a wide range of $10 to $250 every month for drug therapy.
There is no known mode of prevention for feline asthma, though it should be obvious that afflicted cats should not be bred. Ideally, none of their first-degree relatives should be bred, either, particularly if the condition manifests severely.
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