Cause
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.
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.
Diagnosis
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.
Treatment
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
Prevention
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