What is the most common cause of community-acquired pneumonia in cats?

The most common cause of community-acquired pneumonia in cats is Mycoplasma. Mycoplasma species are often associated with respiratory conditions in cats, particularly in younger or immunocompromised individuals. They can cause interstitial pneumonia and have been documented as opportunistic pathogens, especially when the respiratory tract is compromised due to other underlying issues.

In cats, Mycoplasma can lead to chronic respiratory problems and is frequently isolated in cases of pneumonia associated with feline viral diseases, further complicating the clinical picture. The bacterial nature of Mycoplasma allows it to thrive in the respiratory epithelium, contributing to inflammation and pneumonia.

While other pathogens like Streptococcus pneumoniae, Chlamydia felis, and various viral infections can also cause respiratory issues or pneumonia, they are less common as primary agents of community-acquired pneumonia in feline patients. Streptococcus pneumoniae is more associated with humans, Chlamydia felis typically causes conjunctivitis and respiratory disease rather than pneumonia on its own, and viral infections often serve as predisposing factors rather than direct causes.