Chlamydophilosis in cats


Caused by the bacterium Chlamydophila felis, Feline chlamydophilosis is considered a relatively severe disease. The main health implication following infection from this is conjunctivitis. It is very rare for this bacterium to infect other species since it is highly adapted to using cats as a host and human chlamydia is caused by a different, albeit similar, pathogen. The bacteria are intracellular which means they are found inside the cells of the host’s tissues, in this case those of the cat. It enters and reproduces in the lining of the eye lids where it causes high levels of damage to the cells and is able to travel to other areas of the body where epithelial cells are found. Kittens are more susceptible as they have an underdeveloped immune system although cats at any age can become infected with the bacteria. Vaccines can be given as a preventative measure against this disease which can prevent infection or result in any infection which may occur being much milder in its effects.


Transmission occurs via direct contact between the cats or the infected ocular discharge. Kittens are able to catch the disease during the process of their mother giving birth and so care should be taken with infected and pregnant queens.

This disease is more commonly seen in areas of overcrowding and stress such as multi-cat households and boarding catteries. Animal shelters are considered stressful environments and this can also spread the disease amongst the cats within them. Fortunately, the bacteria do not survive very long outside the host and so transmission from the surrounding environment is not seen as a large risk. It is rare for transmission to occur via infected objects such as food bowls. However, most disinfectants on inanimate surfaces can be used to destroy the bacteria.


Conjunctivitis can be observed in the form of different levels of severity as well as sneezing and nasal discharge. Concerning the conjunctivitis, the symptoms begin with ocular discharge and one or both eyes may become partially closed. The discharge progresses from a watery to a more yellow and viscous substance. In addition, redness and swelling will be observed around the lining of the eyelids. Fever may develop and as a result, lethargy and a lack of appetite. Feline chlamydophilosis is more commonly seen in kittens ranging from five to twelve weeks of age.

Treatment and Prevention

Eye drops are administered and a wide range of antibiotics may be used. Medicine can also be applied orally. To prevent further transmission, all the cats should be treated within the household regardless of whether they show any signs or symptoms. Additionally, hands should be thoroughly washed, when treating an infected cat.

Vaccination is recommended and, although it may not completely prevent infection, the disease is much milder as opposed to how it would be in unvaccinated cats. Kittens should be vaccinated twice between nine and twelve weeks of age. To provide long term protection against feline chlamydophilosis, annual boosters are highly recommended.

Diagnosis and Prognosis

The disease can be diagnosed by obtaining swabs around the eyes and isolating the bacteria. Cultures are then grown and identified. The prognosis, if caught in time, is usually good though kittens may have reoccurring infections throughout their life. It has been seen that some kittens develop pneumonia after contracting the disease.


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