Chlamydia is typically associated with venereal disease in humans, but the bacteria can cause cats to suffer feline chlamydiosis, which looks like conjunctivitis and an upper respiratory infection. It’s not life-threatening, but for cats who live outside or spend time at groomers, kennels, or around other cats, vaccination against the disease is a good idea.


Feline chlamydiosis (also called feline pneumonitis) is caused by the bacterial organism Chlamydophila felis (C. felis). The C. felis organism does not live for very long in the environment, so infection is generally spread through direct or close contact with a sick cat. Because infected cats sometimes sneeze, contact with these droplets can also spread the infection.

The primary clinical sign associated with feline chlamydiosis infection is conjunctivitis (inflammation of the inner eyelids and associated tissues). When conjunctivitis occurs, the eyes can become bloodshot and often develop a discharge. The discharge may be watery or thicker, resembling mucus. One or both eyes may be affected. Sometimes an infected cat may squint or rub its eyes.

Because feline chlamydiosis can occur along with other organisms that cause a feline respiratory infection (commonly called a feline cold), clinical signs associated with the other organisms can also be observed. These can include a runny nose, lethargy (tiredness), coughing, and a more severe respiratory infection that can progress to pneumonia.

Treatment generally consists of administering antibiotics, which may be given by mouth or injection, applied as ointment or drops to the eyes, or given in a combination of these treatment methods. Depending on the severity of infection, many cats begin to improve within the first few days of treatment. Following recovery, some cats can become chronically infected with the disease. For these cats, the clinical signs may return later in life and may require additional treatment.

Vaccine Characteristics

Vaccination against C. felis reduces the severity of clinical signs in an infected cat but does not prevent infection or shedding of the organism into the environment. The feline chlamydia vaccine is considered a non-core vaccine, meaning it is an optional vaccine that cats may benefit from based on their risk for exposure to the disease. Several feline chlamydiosis vaccines are available, all of which have been tested and found to be safe and effective when administered as directed.

The feline chlamydiosis vaccine is not a required vaccine for all cats. Vaccination should be based on risk for exposure to the C. felis organism. Cats who go outside, live with other cats, or visit grooming or boarding facilities are at greater risk for exposure than cats who stay indoors and have limited contact with other cats.

Vaccination Schedule

Vaccination decisions should always be made in consultation with a veterinarian so they can be tailored to meet a cat’s individual needs.

According to the American Association Feline Practitioners vaccination guidelines, the feline chlamydiosis vaccine is recommended for cats according to the following schedule: Kittens should receive an initial dose as early as 9 weeks of age; a second dose is administered three to four weeks later.

Adult cats (older than 16 weeks) should receive an initial dose, followed by a booster three to four weeks later.

An annual booster is indicated for cats with sustained exposure risk.


Administering a vaccine is a medical procedure, and there are times when a vaccine may not be recommended. For example, your veterinarian may advise against vaccinating an animal that is currently sick, pregnant, or may not have adequate immune system functioning to respond to a vaccination. These and other issues are evaluated when deciding what is best for your cat.

Other Considerations

Feline chlamydiosis is contagious to other cats, but it is not generally considered contagious to humans. However, people who may have a compromised (weakened) immune system should notify their physician if their cat is diagnosed with feline chlamydiosis. Routine household disinfectants and detergents kill the C. felis organism, so keeping the environment clean is a good way to reduce the risk of disease spread. Also, keeping sick cats separated from healthy cats can reduce the likelihood of transmission. Any new kitten or cat being introduced into the home should be examined by a veterinarian as soon as possible and separated from all other household pets for a quarantine period. During that time, the new cat should be monitored closely for any signs of illness. Any problems should be reported to your veterinarian before introducing the new cat to your other pets.


American Association Feline Practitioners vaccination guidelines 

This article has been reviewed by a Veterinarian.