Conjunctivitis and keratoconjunctivitis associated with chlamydiae in swine.

Two swine herds housed in confinement had high prevalences of conjunctivitis and keratoconjunctivitis. Necropsies were performed on 7 pigs (2 to 8 weeks old) with mucopurulent conjunctivitis from one farm and on 1 sow with keratoconjunctivitis from another farm. Histologically, the small pigs had lymphoplasmacytic conjunctivitis with mild lymphofollicular hyperplasia. The sow had marked conjunctival lymphofollicular hyperplasia and ulcerative keratitis with neovascularization. Ultrastructural examination of conjunctival specimens from the pigs and sow revealed chlamydiae, often associated with glycogen within intracytoplasmic vacuoles in conjunctival cells. The identity of the chlamydiae isolated from 2 necropsied pigs as well as from conjunctival swab specimens from other pigs on the same farm was unknown. It is possible that the chlamydiae seen ultrastructurally within intracytoplasmic vacuoles containing glycogen in conjunctival cells were Chlamydia trachomatis. Results of this investigation suggested an etiologic role, at least in part, for chlamydiae in the disease process of these swine. On the basis of ultrastructural findings, mycoplasmal coinfection could not be ruled out. Several pigs also had cytomegalic inclusion virus rhinitis.