Chlamydia in Cats: A Common but Treatable Eye Infection

In this guide

Despite the name recognition from human health contexts, feline chlamydia is a different organism, Chlamydia felis, and a different disease altogether. It is a genuinely common cause of eye infections in cats, especially kittens and cats from multi-cat households, catteries, or shelter backgrounds, and it responds well to the right antibiotic once correctly identified.

How it shows up

• Conjunctivitis, usually starting in one eye and spreading to the other within a few days
• Watery discharge that becomes thicker and yellowish as the infection progresses
• Redness and swelling of the tissue around the eye
• Squinting or discomfort
• Mild sneezing or nasal discharge in some cats, though the eyes are usually affected first and most severely

Kittens under nine months are the most commonly affected group, and it spreads easily between cats sharing space, making it a frequent visitor in multi-cat homes and breeding catteries.

Diagnosis and treatment

A vet will usually take a swab from the conjunctiva for PCR testing to confirm chlamydia rather than a similar-looking viral conjunctivitis, since the two need different treatment. Once confirmed, doxycycline is the antibiotic of choice, typically given for a minimum of four weeks, notably longer than most other feline infections, because chlamydia tends to linger in tissue beyond the eye itself, including the respiratory and reproductive tract, and a short course often just masks symptoms without clearing the infection. In multi-cat households, vets often recommend treating every cat in the home together, even those without visible symptoms, since silent carriers are common and can reinfect treated cats.

A quick practical note: doxycycline tablets should always be followed with food or a small amount of water, since dry-swallowing this particular medication has been linked to oesophageal irritation in cats. A little wet food afterwards makes a real difference.

Should you worry about your own eyes

Human infection with the cat-specific strain is rare but not impossible, and has been documented in a small number of case reports, usually in people with very close, prolonged contact with an infected cat. Basic hygiene, washing hands after handling an infected cat's face or applying eye medication, is sensible, and anyone who develops persistent eye redness alongside a household chlamydia diagnosis in their cat should mention the cat's diagnosis to their doctor.

Preventing spread

• Isolate a newly diagnosed cat from other household cats where practical during the first week or two of treatment
• Wash hands and any shared bedding thoroughly
• Complete the full antibiotic course even once the eyes look normal again, since stopping early is the most common reason for relapse
• Ask your vet about a chlamydia vaccine if you run a multi-cat household or cattery with recurring outbreaks

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