If, gradually over time, your cat has come to have difficulty breathing, at first after exertion but eventually even at rest, make an appointment with your veterinarian immediately as your cat may have developed a form of emphysema, which can be painful, stressful, and possibly terminal. 

As with humans and many other animals, when a cat breathes in, air travels down the trachea, through the right and left bronchus, down through the narrowing pathways of the bronchi, and eventually into bunches of small grape-shaped sacs that are connected at the end of each bronchiole. These sacs, called pulmonary alveoli, are the mechanism through which oxygen enters the blood, a process called perfusion, and carbon dioxide is extracted from the blood and then exhaled through the reversal of this process. This entire process is called ventilation. Emphysema is a category of diseases that result in air being trapped within the respiratory system. 

The signs of emphysema are the direct results of the damage to the pulmonary alveoli, which results in air being trapped in the lungs and poor blood oxygenation. The symptoms for look for with emphysema are as follows:

One form of emphysema that can affect cats is alveolar emphysema. Alveolar emphysema is a disease that damages the inner surface of the pulmonary alveoli, which causes air that is heavy in carbon dioxide to become trapped. This trapped air prevents oxygen-rich fresh air from entering into the pulmonary alveoli and then into the blood, resulting in labored breathing and low blood oxygenation. 

The second type of emphysema that can affect cats is referred to as interstitial emphysema. This condition is the result of the rupture of alveoli sacs or bronchial rupture, both of which result in air becoming trapped in the supportive connective tissue of the lungs.

While many cases of feline emphysema may be idiopathic, meaning the cause is not known, it is believed that many cases may be a secondary condition that results from asthma or chronic bronchitis. Both of these conditions often result in the lungs becoming overinflated on a repeated, yet temporary, basis, which can eventually result in permanent damage to alveoli and bronchial tubes. This permanent damage causes air to be trapped in the respiratory system on a more permanent basis and prevents fresh oxygenated air from being inhaled in order to oxygenate the blood. Asthma and chronic bronchitis are both heavily influenced by air quality and are often exacerbated by smoke and allergens. Middle-aged and older cats tend to be most susceptible to emphysema.

After listening to your report of the symptoms you have observed and after reviewing your cat’s medical history, the veterinarian will do a thorough physical examination of your cat. During this examination the vet will take special care when listening to the cat’s breath with a stethoscope to hear if the breathing sounds wheezy or has a rattle or crackle sound to it. The most difficult aspect of diagnosing emphysema in a cat is ruling out the numerous other conditions that could be causing the coughing and breathing issues. These conditions include various bacterial and viral infections such as pneumonia. In order to rule out these other conditions, the vet may utilize the following diagnostic procedures:

Emphysema is irreversible, but it is often treatable. Because the damaged pulmonary tissue cannot be repaired or restored, treatment concentrates on suppressing chronic coughing and opening up the airways as much as possible so the trapped air can be released. Your veterinarian will likely treat your cat’s emphysema using some of the following methods:            

While emphysema cannot be cured, a cat that is provided with consistent treatment for the underlying condition can often live a normal lifespan. There may be times of year when allergens and poor air quality may cause episodes of breathing difficulty, but when under a veterinarian’s care, a cat owner can usually be cautiously optimistic regarding their cat’s long-term prognosis. This prognosis, however, will be highly contingent upon the age and overall health of the cat.