Chlamydial Conjunctivitis in Cats
What is feline chlamydial conjunctivitis?
Feline chlamydial conjunctivitis is an infection caused by a bacterial organism (called Chlamydophila felis). The most common signs of chlamydia in cats involve the eyes or the upper respiratory tract (nose or throat), and only when infection is not treated does it spread to the lungs. This bacteria has also been reported to infect the genital tract and joints.
How does a cat become infected with chlamydial?
Because chlamydia lives inside cells of the body and is not able to survive for long in the environment, spread of infection relies on direct or close contact with an infected cat. Following infection, the incubation period (the time between infection and development of clinical signs of disease) is between three and ten days.
Which cats are most at risk for this disease?
Young cats and kittens are especially vulnerable to this infection, although chlamydia can be detected in cats of all ages. It is one of the most common causes of infectious conjunctivitis in cats.
What clinical signs does a cat infected with chlamydia develop?
The bacteria primarily infects the conjunctiva, which are the delicate membranes lining the eyelids and covering the edges of the eyeballs. The infection causes inflammation known as conjunctivitis. In normal cats, the conjunctiva is not readily visible and has a pale, salmon pink color. In cats with conjunctivitis, the conjunctiva becomes swollen and red, making it more visible. The nictitating membrane or third eyelid in the inner corner of the eye may protrude partially across the eye. One or both eyes may be involved.
Affected cats initially develop a watery discharge from the eyes that quickly becomes thicker and is usually a yellow or greenish color. The eyes are uncomfortable and cats often keep the affected eye(s) closed. Many cats remain bright and otherwise appear normal, but some may develop a fever or lose their appetite. After one or two days, sniffles and sneezing may also occur. In kittens, the infection may spread to the lungs and cause a fatal pneumonia.
"Affected cats initially develop a watery discharge from the eyes that quickly becomes thicker and is usually a yellow or greenish color."
If left untreated, the conjunctivitis and associated discomfort and discharge may persist for several weeks or months during which time the cat is a source of infection to other cats. Infected cats may appear to recover and then develop a relapse.
How is chlamydial conjunctivitis be diagnosed?
Chlamydial conjunctivitis can be difficult to diagnose because there are many causes of conjunctivitis and cats may have multiple infections at the same time. The preferred method of diagnosis involves taking a swab sample from the conjunctival membrane. The swab is then sent to a laboratory where the sample is grown in culture and subsequently identified. Occasionally, the organisms are visible in stained smears prepared from conjunctival scrapings.
Another diagnostic option is testing conjunctival scrapings and swabs for chlamydia antigens and DNA. This test can be useful in cases where the laboratory culture result is negative or as a general screening test for catteries or multi-cat households where conjunctivitis is a chronic problem.
Are other cats in the household at risk of infection?
Chlamydia is spread by close or direct contact with an infected cat, so all cats in the home can become infected. For this reason, if one cat in the home is diagnosed, all cats in the household should be treated.
Is my family at risk?
There are isolated reports of people who live in the same household as affected cats developing feline chlamydia-associated conjunctivitis. Therefore, if anyone in your household develops sore or runny eyes, they should consult their doctor and tell him or her that there is a chlamydial infection in the household cat. Such infection is extremely uncommon and once diagnosed is readily treatable.
Is there any treatment for chlamydial conjunctivitis?
Chlamydia can be successfully treated with a course of oral and topical antibiotics. Only certain antibiotics are able to penetrate inside the cells where the bacteria live. Treatment must be continued for a minimum of four weeks and for at least ten days after the eyes appear normal. Since some cats can be infected sub-clinically (not show signs themselves, but act as a source of infection to other cats) treatment should be given to all of the cats in the household.
"Since some cats can be infected sub-clinically treatment should be given to all of the cats in the household."
Although the infection can be debilitating in some cats, it is treatable with a low risk of recurrence as long as the entire household is thoroughly treated.
How can chlamydial conjunctivitis be prevented?
Various vaccines are available and are most useful in breeding catteries or animal shelters where it can be difficult to eliminate the organism completely. This vaccine is considered a non-core vaccine and is recommended if your cat is at reasonable risk for contracting the disease. The protection afforded by the vaccine is relatively short, and annual boosters are usually required. Your veterinarian will advise you on the appropriate vaccination choices for your cat, based on the prevalence of this disease in your area and your cat’s individual risk.
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