Feline chlamydiosis or pneumonitis is a fairly common disease that is caused by infection with a Chlamydia (also called Chlamydophila) bacteria. These microorganisms are very contagious, and cats that do not have strong immune systems (e.g., young kittens) or those that come into contact with lots of other cats (e.g., those residing in animal shelters) are most at risk. In rare cases, Chlamydia bacteria may be transmitted from cats to people, so be sure to wash your hands well after handling an infected animal.




Cats with chlamydiosis have red, swollen and painful eyes with either a clear or a thick, discolored discharge. Commonly, only one eye is involved early in the course of the disease, but within a few days both eyes show similar symptoms. Some cats may also have a fever and sneeze. Many veterinarians will diagnose chlamydiosis based on clinical signs alone, but if a more definitive identification is required, samples that are gently scraped from the mucous membranes around the cat's eyes can be tested for the bacteria.




Antibiotic eye ointments are the mainstay of treatment for feline chlamydiosis. Oral antibiotics may be required in severe cases. Supportive care, including keeping the cat's eyes and nose clear of discharge and encouraging it to eat and drink is also extremely helpful. A vaccine that can lessen the severity of chlamydiosis is available. Most cats recover uneventfully after two to three weeks, but a few may have occasional flare-ups of the disease or develop long-lasting eye abnormalities.


Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008