Feline Asthma

What is Asthma?

Asthma is a recurring respiratory compromise featuring constriction of the lung’s airways. First, excess mucus forms, then the airway walls swell with inflammation and can actually ulcerate, and finally the airway muscles go into spasm, which leads to constriction. Airway constriction leads to inability to draw a deep breath, intolerance to exercise, coughing, and musical sighing sounds called wheezes, though not all these symptoms may be apparent at the same time. Sometimes a low-grade chronic cough is the only manifested sign but an acute asthmatic crisis can arise at any time and can represent a life-threatening event. Asthmatic airway constriction can happen spontaneously or as a type of allergic reaction. When it comes to treatment, relieving and preventing airway constriction is what it is all about.

Is Feline Asthma the Same as Human Asthma?

The feline condition was named asthma due to the clinical features shared with the human disease. As of this time, it appears that all the diagnostic criteria needed to make the asthma diagnosis in humans are shared by cats, yet we are still working out the mechanics of this syndrome in cats and have a great deal to learn. For example, in humans we know that while actual symptoms of asthma occur in episodes, the airways of the lung are diseased all the time. We do not know yet if feline airways are also diseased all the time or if the actual airway structural changes occur only when there are clinical signs of distress.

How is the Diagnosis Made?

Because of the constricted airways, the actual volume of air this patient can move in and out of the lungs in each breath is reduced. Often there is a great deal of effort seen in the cat’s breathing. The abdomen appears to be working to push air out and the breaths are shallow and rapid. The cat may even be breathing with the mouth open in an effort to move the largest possible amount of air.

The next step toward making a diagnosis of feline asthma is the chest radiograph, assuming the cat is not in too much distress to hold still in position for this procedure. Classically, this radiograph will show asthmatic cats have what is called air-trapping. This means that the small airways have constricted to the extent that inhaled air cannot be exhaled. The lungs are larger in appearance than normal as they are over-inflated. The diaphragm may seem flattened due to this over-inflation. 

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