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Pet Owner Version

Chlamydial Conjunctivitis in Cats (Feline Pneumonitis)


Kirk N. Gelatt

, VMD, DACVO, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida

Reviewed/Revised Jul 2018 | Modified Oct 2022

Chlamydial conjunctivitis is an infection of the membrane around the eye (the conjunctiva). Different strains of Chlamydia felis and Chlamydia pneumoniae bacteria cause significant eye infections in cats. The disease in cats is also known as feline pneumonitis, which can be misleading because these bacteria rarely cause pneumonia in cats. The infection usually involves the eye and occasionally the nose. Most affected cats are less than a year old.

Signs in cats include clear or colored discharge from the eyes; reddened, swollen conjunctivae in one or both eyes (conjunctivitis); discharge from the nose; and sneezing. The signs are most severe 9 to 13 days after onset and then subside over 2 to 3 weeks. In some cats, however, signs can last for weeks despite treatment, and recurrence is not uncommon. Untreated cats can spread the infection to other cats for months after an infection.

Your veterinarian can confirm the diagnosis by taking a smear from the conjunctiva and finding the chlamydial organism on laboratory tests or under a microscope. It is important to identify the organism causing conjunctivitis in order to provide effective treatment.

Your veterinarian can prescribe antibiotics to treat the infection. Treatment usually lasts 4 to 6 weeks. Be sure to follow directions carefully and for the full period prescribed by your veterinarian. To reduce recurrence, treatment in cats is usually continued after signs disappear. So, even though your cat looks better, be sure to follow the treatment program for the full length of time prescribed.

Vaccines are available for chlamydiosis in cats. The vaccine does not completely protect the cat from infection, but it can significantly reduce the severity and likelihood of infection. You may want to discuss with your veterinarian whether vaccination is appropriate for your cat.

There have been occasional reports of transmission of the Chlamydia bacteria from cats to people, so frequent hand-washing and other good hygiene measures are recommended when treating a sick cat to reduce the chance of infection in people.

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