Chlamydia in Cats Treatment: Signs and Diagnosis

Chlamydia in Cats Treatment: Chlamydia in cats, also known as feline chlamydiosis, is an infection caused by the bacteria Chlamydia felis. This obligate intracellular parasite affects the conjunctiva and upper respiratory tract of cats. The infection is usually transmitted between cats through direct contact with infected eye or nasal secretions.

Clinical Signs

The most common signs of chlamydia infection in cats include:

  • Conjunctivitis: Inflammation of the conjunctiva or the pink tissue surrounding the eye. It leads to red, swollen eyes that produce thick, yellow discharge.
  • Nasal discharge: Excessive sneezing and a clear, watery nasal discharge. The discharge may become thick and yellow over time.
  • Coughing: A dry, hacking cough may develop as the infection progresses to the lower respiratory tract.
  • Lethargy: Some cats may become lethargic and lose their appetite due to the infection.
  • Fever: An elevated body temperature is occasionally seen with chlamydia infection.


A presumptive diagnosis of chlamydia infection can be made based on clinical signs. Definitive diagnosis requires laboratory testing of conjunctival or nasal swabs. Tests used include:

  • Polymerase chain reaction (PCR) assay: The most sensitive test, it detects chlamydial DNA.
  • Enzyme-linked immunosorbent assay (ELISA): Detects chlamydial antigens.
  • Microscopic examination: Chlamydial inclusions can sometimes be seen in stained cells.
  • Serology: Blood tests to detect chlamydial antibodies. A four-fold rise in antibody titers helps confirm active infection.
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Chlamydia in cats Treatment

There are several medications available to treat chlamydia in cats, including tetracycline antibiotics such as doxycycline, as well as macrolide antibiotics such as azithromycin. These antibiotics are usually administered orally for several weeks to eliminate the infection.

1. Doxycycline

Doxycycline is a broad-spectrum tetracycline antibiotic commonly used to treat chlamydia in cats. It works by inhibiting bacterial protein synthesis to stop the growth of chlamydia bacteria. The typical dosage for cats is 5 to 10 mg/kg of doxycycline hyclate once a day for at least 4 weeks. Side effects may include gastrointestinal upset, so giving the medication with food can help minimize issues. Doxycycline should not be used in young kittens, as it can damage their teeth.

2. Azithromycin

Azithromycin is a macrolide antibiotic used as an alternative treatment for chlamydia in cats. It works similarly to doxycycline by disrupting bacterial protein synthesis. The dosage for cats is typically 10 to 15 mg/kg once a day for 7 to 10 days. Azithromycin may cause some gastrointestinal side effects. It is considered safe for use in kittens and has fewer side effects than doxycycline.

In severe or persistent cases of chlamydia, hospitalization and fluid therapy may be required to help support the cat during treatment. Re-testing for chlamydia 2 to 4 weeks after treatment is completed is recommended to confirm elimination of the infection before ending isolation procedures. With prompt and appropriate treatment, most cats will recover fully from chlamydia. However, some cats may become chronic carriers of the bacteria even with treatment.

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How do cats get infected with Chlamydia?

Chlamydia in cats is caused by a bacterial infection known as Chlamydia felis. This obligate intracellular parasite requires a host cell to survive and reproduce. Cats become infected through direct contact with infected secretions, especially during mating or childbirth. The bacteria can also be transmitted from an infected mother to her kittens during the birthing process.

What are the symptoms of Chlamydia in cats?

Infected cats may exhibit a variety of symptoms, including conjunctivitis, rhinitis, pneumonia, and reproductive problems. The most common symptoms are inflammation of the eyes (conjunctivitis) and nasal passages (rhinitis), resulting in ocular and nasal discharge. In severe cases, Chlamydia can lead to pneumonia, causing coughing, sneezing, and difficulty breathing. Reproductive issues such as infertility, abortion, and stillbirths may also occur in infected females. Some cats may remain asymptomatic, acting as reservoirs for the infection.

How is Chlamydia diagnosed in cats?

Diagnosing Chlamydia in cats begins with a physical exam and health history. Swabs of the conjunctiva, vagina, and respiratory tract are collected for cytology and Chlamydia testing. Blood tests to check for Chlamydia antibodies may also be performed. The most accurate diagnostic tests for Chlamydia are polymerase chain reaction (PCR) assays, which detect the DNA of Chlamydia organisms in clinical samples. PCR testing of conjunctival and vaginal swabs provides a definitive diagnosis in most cases.

How is Chlamydia treated in cats?

Chlamydia in cats can be treated with a course of antibiotics, typically doxycycline or azithromycin. Doxycycline is commonly administered for a period of 2 to 3 weeks. All cats in the household should be treated to prevent reinfection. Severe or refractory cases may require hospitalization and intravenous antibiotics. Re-testing is recommended 4 to 6 weeks after treatment to ensure elimination of the infection. Supportive care such as eye ointments, fluids, and nutritional support may also be provided depending on the severity of symptoms.

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With prompt diagnosis and proper treatment, most cats recover fully from Chlamydia. However, chronic infections and re-infections can occur, so prevention is key. Practicing good hygiene, quarantining new pets, and regular testing and treatment of breeding animals will help reduce the spread of this disease.