Feline ocular chlamydiosis
Chlamydophila was thought to be responsible for most feline upper respiratory tract infections, but it is much harder to determine its contribution since the isolation of the feline viral rhinotracheitis and calicivirus viruses. The condition is mainly characterised by persistent mild conjunctivitis. More severe signs and more significant lesions, such as corneal ulcers, conjunctival oedema, cough and sneezing, may develop in gravely affected cats.
The disease is primarily characterised by persistent mild conjunctivitis and in some cases mild rhinitis (pulmonary disease is much less common) producing very intense redness with either watery or thick and purulent tears. Unlike feline rhinotracheitis, the infection normally begins in one eye before spreading to the other.Weeks or months later, the cat may still present ocular secretions that need to be treated periodically.
The most affected cats may have more severe signs and develop significant eye injuries, such as corneal ulcers, conjunctival oedema, coughing and sneezing.
The signs are nonspecific as they could be caused by other agents, so the diagnosis is based on clinical suspicion if conjunctivitis is the predominant sign and the patient lives in a multi-cat household, and this should be confirmed by analysing a sample of the secretions.
Treatment is based on long-term antibiotic administration, both topical (1% fusidic acid, chlortetracycline, etc.) and systemic (doxycycline 10 mg/kg/day by mouth).
Studies comparing topical and systemic administration in cats with chlamydial conjunctivitis concluded that systemic therapy with doxycycline was superior to topical therapy in the treatment of feline ocular chlamydiosis. Systemic treatment also produced a greater reduction in disease severity. Of the topical therapies, fusidic acid was totally ineffective. Another study found that topical treatment alone led to a recurrence of chlamydiosis, whereas systemic tetracycline resulted in a faster recovery and long-term, sustained negative cultures and PCR results.
On a different note, patients should receive general care such as cleaning of any secretions.
Vaccination is the only way to prevent chlamydiosis, although it does not always avoid the infection.