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Basics ⬇

Basics

Definition

A chronic respiratory infection of cats caused by an intracellular bacterium, characterized by mild to severe conjunctivitis, mild upper respiratory signs, and mild pneumonitis.

Pathophysiology

  • Chlamydophila felis (previously Chlamydia psittaci var. felis)-an obligate intracellular bacterium; replicates on the mucosa of the upper and lower respiratory epithelium; produces a persistent commensal flora that causes a local irritation with resulting mild upper and lower respiratory signs; can also colonize the mucosa of the gastrointestinal and reproductive tracts.
  • Incubation period-7–10 days; longer than that for other common respiratory pathogens of the cat.

Systems Affected

  • Gastrointestinal-cat: infection without clinical disease; other species: may have clinical gastroenteritis.
  • Ophthalmic-chronic conjunctivitis, often unilateral but may be bilateral.
  • Reproductive-infection without clinical disease.
  • Respiratory-mild rhinitis, bronchitis, and bronchiolitis.

Incidence/Prevalence

  • Incidence of clinical disease-sporadic; outbreaks of respiratory disease may occur, especially in multi-cat facilities.
  • Prevalence of C. felis in the feline population-not uncommon, 5–10% chronically infected.

Geographic Distribution

Worldwide

Signalment

Species

  • Cat
  • Human

Mean Age and Range

Usually cats <1 year of age; any age cat possible.

Signs

General Comments

  • Infection often subclinical.
  • Clinical disease-commonly as a co-infection with other organisms.

Historical Findings

  • Upper respiratory infection, with some sneezing, watery eyes, and coughing.
  • Sometimes difficult breathing.
  • Varying degrees of anorexia.

Physical Examination Findings

  • Conjunctivitis-often granular; initially unilateral, usually progresses to become bilateral.
  • Lacrimation, photophobia, and blepharospasm.
  • Rhinitis with nasal discharge-usually mild.
  • Pneumonitis-with the inflammatory process in the alveoli; bronchiolar tubes and airways give audible rales.

Causes & Risk Factors

  • Concurrent infections with other respiratory pathogens.
  • Lack of vaccination.
  • Multi-cat facilities, especially adoption shelters and breeding catteries.

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Feline viral rhinotracheitis-short incubation period (4–5 days), rapid bilateral conjunctivitis, severe sneezing, and ulcerative keratitis.
  • Feline calicivirus infection-short incubation period (3–5 days), ulcerative stomatitis, and severe pneumonia.
  • Feline reovirus infection-very mild upper respiratory infection; short incubation and duration.
  • Bronchial pneumonia caused by bacteria such as Bordetella bronchiseptica-localized areas of density within the lungs on radiographs.

CBC/Biochemistry/Urinalysis

Leukocytosis

Imaging

Radiographs of lungs-helpful with pneumonitis.

Diagnostic Procedures

  • PCR assay for C. felis-preferred; conjunctival swab sample.
  • Serum antibody assay-unvaccinated cats; indicates infection.
  • Conjunctival scrapings stained with Giemsa stain-characteristic intracytoplasmic inclusions.
  • Swab samples taken from conjunctiva-isolation of the causative organism in cell cultures.

Pathologic Findings

  • Gross-evidence of chronic conjunctivitis with mucopurulent ocular discharge; minor rhinitis with nasal discharge; sometimes lung changes indicative of pneumonitis.
  • Histopathologic (conjunctiva)-an early intense infiltration of neutrophils; inflammatory response changes to lymphocytes and plasma cells; inclusions detected with special stains; inclusions invisible with routine H&E stains.

Treatment ⬆ ⬇

Treatment

Appropriate Health Care

Generally as outpatient

Nursing Care

  • Keep nostrils and eyes clean of discharge.
  • Generally does not require other supportive therapy (e.g., fluids), unless complicated by concurrent infections.

Activity

  • Quarantine affected cats from contact with other cats.
  • Do not allow affected cats to go outside.

Diet

Normal

Client Education

Inform clients of the causative organism, the anticipated chronic course of disease, and the need to vaccinate other cats before exposure.

Medications ⬆ ⬇

Medications

Drug(s) Of Choice

  • Systemic-tetracycline antibiotic of choice (22 mg/kg PO q8h for 3–4 weeks); doxycycline (10 mg/kg q24h PO daily for 4 weeks to prevent recrudescence).
  • Ocular-ophthalmic ointments containing tetracycline (q8h).

Contraindications

Tetracycline-may affect growing teeth of young kittens.

Precautions

Colonies/shelters/breeding catteries-all cats may have to be treated; treatment may have to be continued for as long as 4 weeks.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

Monitor for improved health as treatment proceeds.

Prevention/Avoidance

Vaccines

  • Both inactivated and modified live vaccines are available to reduce the severity of infection.
  • Vaccines do not prevent infection; rather, they reduce severity and duration of clinical disease.
  • American Association of Feline Practitioners-classifies as non-core; for at-risk cats, give a single vaccination at initial visit as early as 9 weeks of age, repeat in 3–4 weeks; revaccinate annually where C. felis is endemic.

Possible Complications

Adverse vaccine reactions-mild clinical disease with modified live vaccines; small percentage of vaccinated cats.

Expected Course and Prognosis

  • Tends to be chronic, lasting for several weeks or months, unless successful antibiotic treatment is given.
  • Prognosis good.

Miscellaneous ⬆

Miscellaneous

Age-Related Factors

Primarily a disease of young cats

Zoonotic Potential

C. felis can infect humans, especially immunocompromised individuals; limited number of reports of mild conjunctivitis in humans transmitted from infected cats.

Pregnancy/Fertility/Breeding

  • Endemic breeding catteries-treat all cats with doxycycline for at least 4 weeks; then vaccinate.
  • Role of C. felis as a pathogen during pregnancy-unclear; can colonize the reproductive mucosa; severe conjunctivitis neonatorum can occur in neonatal kittens infected at or shortly after birth.

Synonym

Feline pneumonitis

Abbreviations

  • H&E = hematoxylin and eosin
  • PCR = polymerase chain reaction

Suggested Reading

Gaskell RM. Upper respiratory disease in the cat (including Chlamydia): Control and prevention. Feline Pract 1993, 21:29–34.

Greene CE, Sykes JE. Chlamydial infections. In: Greene CE, ed., Infectious Diseases of the Dog and Cat, 3rd ed. St. Louis, MO : SaundersElsevier, 2006, pp. 245–252.

Gruffydd-Jones T, Addie D, Belák S, et al. Chlamydophila felis infection: ABCD guidelines on prevention and management. J Feline Med Surg 2009, 11:605–609.

Hoover EA. Viral respiratory diseases and chlamydiosis. In: Holzworth J, ed., Diseases of the Cat. Philadelphia: Saunders, 1987, pp. 214–237.

Richards JR, Elston TH, Ford RB, et al. The 2006American Association of Feline Practioners Feline Vaccine Advisory Panel Report. J Am Vet Med Assoc 2006, 229:1405–1441.

Scherk MA, Ford RB, Gaskell RM, et al. 2013AAFP Feline Vaccination Advisory Panel Report. J Feline Med Surg 2013, 15:785–808.

Sparkes AH, Caney SM, Sturgess CP, et al. The clinical efficacy of topical and systemic therapy for the treatment of feline ocular chlamydiosis. J Feline Med Surg 1999, 1:31–35.

Sykes JE. Feline chlamydiosis. Clin Tech Small Anim Pract 2005, 20:129–134.

Author Fred W. Scott

Consulting Editor Stephen C. Barr

Client Education Handout Available Online