Pet Illnesses

Chlamydia infection in cats

Respiratory disease in cats is a common problem for cat owners and a major concern for veterinary practitioners.

The main reason for this is that there are so many contributing factors to the disease that it can often be difficult to control.

Up until now, veterinarians have been able to vaccinate against most of the major diseases challenging cats today. These being, Feline Enteritis, Feline Flu and more recently, Leukaemia. However, one of the contributing pathogens in the feline respiratory disease complex has been Chlamydia.

Chlamydia are an unusual micro-organism. They are neither bacteria or viruses, but respond to anti-biotics, usually Tetracyclines.


Respiratory disease caused by Chlamydia is mainly characterised by conjunctivitis and is predominantly seen in young cats from 5–9 months of age. Once contracted, cats can be carriers for as long as 18 months post infection.

7-10 day old kittens are also vulnerable to neonatal conjunctivitis with  “sticky-eye” symptoms persisting for some time.

Whilst conjunctivitis is seen as the main clinical sign in cats, other less common conditions include, abortion, polyarthritis and pneumonitis (inflammation of the lungs). Reproductive capability has also been suggested as being impaired by cats contracting this bacterial disease.


Chlamydia infections are traditionally treated with antibiotics. We use Vibravet paste for young cats and Tetracycline tablets for older cats. In immature cats, Tetracycline can cause colouring effects on the cat’s teeth and bone tissue. A tetracycline based eye ointment is no longer available.


The disease can be controlled through vaccination with a Chlamydia vaccine. Depending on your vets preference, the Chlamydia vaccine comes as either a FeVac 4 or FeVac 5  vaccine brand. They both contain the Chlamydia antigen as well as the other Cat Flu and Feline Enteritis. The only difference between the two vaccines is the inclusion of Feline Leukaemia in Fel-O-Vax 5.

Kittens, 8 weeks of age and older and previously unvaccinated cats will require two doses 3-4 weeks apart. Annual boosting with a single dose of vaccine is recommended for adult cats.

See also...
Annual Health Checks and Vaccines
Feline AIDS (FIV)