This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Note for Pet Owners:
NOTE Chlamydial infections can be transmitted to humans. They therefore represent a Zoonosis and precautions should be taken by people such as veterinary personnel and owners when handling infected animals

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Chlamydial infections can affect a variety of species including birds, cats, dogs, sheep, and humans.

Chlamydia are obligatory intracellular bacteria that contain both DNA and RNA. They have a cell wall and are affected by some antibiotics. C.psittaci is a main pathogen in birds and others. In cats the pathogen is chlamydofila felis. Each strain is species specific and causes respiratory, genital or systemic disease.

Serological surveys

Cats : There is a high prevalence of contact with Chlamydofila felis in cats based on serological screening (45% of farm cats, and 30% of household cats showing conjunctivitis).

Dogs : Up to 50% of normal healthy dogs have antibodies to Chlamydia.

Breed Occurrence
There is no breed specific increased incidence .


Cats : Chlamydofila  felis is a common cause of conjunctivitis which often affects one eye a few days before the second one gets inflamed. Affected cats have inflammation of the conjunctiva, blepharospasm and an ocular discharge. Cats with feline immunodeficiency virus  infection may develop prolonged signs. Chlamydia may be involved in genital infections of cats - but this is inconclusive.

Dogs : Chlamydia have been suggested to cause chronic keratitis in dogs, but they are also found in the eyes of normal dogs, so the significance is not proved. Only isolated cases of infection has been reported - possibly indicating transmission from other species e.g. budgerigars.



Generally swabs taken from superficial sites or aspirations from deeper tissues are examined directly for inclusions, or cultured on McCoy tissue cultures. Fluorescent antibody techniques are highly specific, and there are some ELISA tests available but interpretation is problematic.

Cats : Intracellular chlamydial inclusions can be seen in epithelial cells collected by swabbing the conjunctival membrane, or on positive fluorescent antibody testing of conjunctival scrapes. Chlamydia can be isolated from faeces and rectal swabs and may inhabit the genital tract.


Oral tetracycline is the treatment of choice (except for superficial infections) at a dose rate of 22 mg/kg three times daily for 3-4 weeks. Alternatively doxycycline at 5-10 mg/kg twice daily for 3-4 weeks.

Cats : Treat conjunctivitis due to Chlamydofila felis  with topical tetracycline ointment administered four times daily for 2 weeks. Some authors recommend oral tetracycline or doxycycline as well. To eliminate the disease from a colony ALL cats have to be treated with doxycycline for 6 weeks, and kittening should occur in isolation.

NB Zoonosis Risk


Chlamydia have a lipid-containing cell wall that is susceptible to lipid solvents and detergents so quaternary ammonium compounds diluted 1:1000 are recommended for environmental cleaning.

Maternal antibodies provide protection in kittens until they are 7-9 weeks of age Live and killed vaccines are available for prevention . Sometimes a transient fever, anorexia and lameness are seen 1-3 weeks post-vaccination

The prognosis is good in individuals showing just conjunctivitis.

Long term problems

Because Chlamydia are intracellular organisms complete elimination may not be possible from some individuals and they can become chronic carriers of the disease

Updated January 2016