Chlamydia target mucosal tissues and the primary target for Chlamydophila felis is the conjunctiva. The incubation period is generally 2-5 days. In the first day or two after clinical signs develop, unilateral ocular disease may be seen, but this generally progresses to become bilateral. There can be intense conjunctivitis with extreme hyperaemia of the nictitating membrane, blepharospasm and ocular discomfort. Ocular discharges are initially watery but later become mucoid or mucopurulent. Chemosis of the conjunctiva is a characteristic feature of chlamydiosis. Respiratory signs are generally minimal with Chlamydophila infections. In cats with respiratory disease but without concurrent ocular signs, C felis infection is unlikely. Ocular complications such as adhesions of the conjunctiva, may occur but keratitis and corneal ulcers are not generally associated with infection. Transient fever, inappetence and weight loss may occur shortly after infection, although most cats remain well and continue to eat. Chlamydial organisms can be isolated from the vagina and rectum of cats, but it is unclear whether venereal transmission occurs. Although there is circumstantial evidence that chlamydophila may cause abortion, there is no evidence of a link with gastro-intestinal disease.
Most cats cease conjunctival shedding at around 60 days after infection, although some cats may continue to harbour persistent infection [O’Dair et al 1994] and C felis has been isolated from the conjunctiva of untreated cats for up to 215 days after experimental infection [Wills, 1986].