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Chlamydia in Cats

Chlamydophila felis (formerly known as Chlamydia psittici) is a common disease caused by an intracellular bacterium (a bacterium which lives inside the host's cells). Chlamydia psittaci has been reclassified by veterinary microbiologists. The family Chlamydiae is now divided into two genera, Chlamydia and Chlamydophila. The genus Chlamydophila contains four species, including Chlamydophila felis, a causative agent for conjunctivitis in cats.

Pneumonitis was a term used to describe upper respiratory infections and it was originally believed that the culprit was Chlamydia psittaci.

This was due to isolation of the bacterium from cats with "pneumonitis". Pneumonitis means "inflammation of the lungs".It was later realised that Chlamydophilia felis is not the main cause of respiratory disease in cats, but feline viral rhinotracheitis and feline calicivirus are the cause of the majority of feline respiratory diseases.

Chlamydophila felis doesn't survive well in the environment and is easily killed by routine disinfection.

What are the symptoms of Feline Chlamydophila?

The predominant clinical sign of C. Felis is conjunctivitis; an abnormal eye discharge due to inflammation of the conjunctiva, the membrane lining the inside of the eyelid and the white part of the eye itself, (known as the sclera). The eyes initially develop a watery  discharge, as the infection progresses, the conjunctiva becomes reddened and swollen and the discharge becomes thicker. It may start out with discharge from one eye but usually, spreads to both eyes. Symptoms usually appear around 5 days after exposure.

Mild upper respiratory symptoms such as low-grade fever, nasal discharge, and sneezing may also be present.

It is possible for a cat to appear outwardly healthy but be shedding the bacteria which can be passed onto other cats via eye discharge.

What does Feline Chlamydophila do?

Chlamydophila felis attach themselves to the mucosal cells of the conjunctiva, gastrointestinal and genital tracts. The eyes become red, inflamed and develop a discharge.

In young kittens, chlamydiosis may cause pneumonia.

How do cats become infected?

Direct: Contact with an infected cat, such as nasal and ocular discharges. Kittens may become infected during the birth process.

Indirect: Unlikely as Chlamydophila felis doesn't survive well in the environment, contact with food bowls, bedding, litter trays, pet owner's hands etc. It is always advisable to exercise caution when dealing with infected cats and practice routine hand washing and disinfecting in order to minimise the risks of infecting other cats.

Which cats are at risk?

Chlamydiosis can affect any cats but it is more often seen in kittens between 5 and 9 months of age and cats in overcrowded or stressful environments such as animal shelters.

How is Feline Chlamydophila diagnosed?

Diagnosis may be tentatively made based on clinical symptoms. Your veterinarian will take an eye swab from an infected cat which will be sent to a laboratory for testing. There are several tests which can be performed, including PCR (polymerase chain reaction), Immunofluorescent assay (IFA) or bacterial culture.

How is Chlamydophilia in cats treated?

Antibiotic eye ointment (usually tetracycline) or oral antibiotics will be prescribed. In some cases, a steroid-based antibiotic ointment will be given.

Cats with Chlamydophilia may also become dehydrated, in which case he will be given IV fluids.

Encouraging your cat to eat is important, cats with URI's can lose their appetite.

Prevention of Feline Chlamydophila:

Vaccination. There is a vaccination available for Chlamydophila felis. It can reduce the severity of symptoms but doesn't prevent infection in the first place. There are side effects associated with a small percentage of cats including lethargy, lameness, depression, anorexia, fever and therefore it is only recommended for high-risk situations. The use of this vaccine and as such the American Association of Feline Practitioners don't recommend routine use of this vaccination.

Routine disinfection. Chlamydophila felis is easily killed in the environment and proper hygiene control is recommended.

Also see:

Cat flu   Cat symptoms