In animals, as in humans, pneumonia is an infection or inflammation of the lungs. Dogs and cats can develop pneumonia for several reasons, and pneumonia is usually a complication of an underlying problem. “Community-acquired pneumonia”, which is the most common form of pneumonia in people (often a resulting from a cold, or the flu), is rare in pets. In other words, when pneumonia is confirmed in a dog or cat, it is essential to search for the underlying cause with medical tests, such as blood and urine tests, and to treat both the pneumonia and, whenever possible, the underlying cause as well. Pneumonia often produces generalized symptoms like most other infections in animals: lethargy or tiredness, poor appetite, and so forth. In addition, animals with pneumonia may also develop specific respiratory symptoms as a result of the infection within the lung tissue. These symptoms can include shortness of breath, coughing, raspy or fluid-sounding respirations, hacking, and gagging. It is important to know that symptoms of pneumonia in dogs and cats may be subtle, so the absence of visible symptoms should not be used for assuming that pneumonia is absent.
It is also important to keep in mind that many disorders other than pneumonia can produce these same symptoms, so a dog or cat cannot be known to have pneumonia, even by the most skilled veterinarian, without diagnostic tests such as radiographs (x-rays) of the chest.