Chlamydia pecorum Infection Associated with Ocular Disease in Goats in Alabama, USA

A herd of approximately 300 Spanish meat goats in central Alabama experienced sporadic ocular, respiratory, and reproductive diseases over two years, prompting diagnostic investigation at Auburn University's JT Vaughan Large Animal Teaching Hospital. Five representative doelings exhibiting ocular lesions were examined. Clinical signs included conjunctivitis, corneal opacity, uveitis, and, in one severe case, systemic illness. Initial treatment with topical and systemic antibiotics provided incomplete resolution, raising suspicion of infectious keratoconjunctivitis of atypical etiology. Comprehensive diagnostic testing was performed, including aerobic and <i>Mycoplasma</i> cultures, Giemsa staining, and molecular assays. <i>Moraxella bovoculi</i> was cultured; however, Giemsa staining revealed <i>Chlamydia</i> elementary bodies, and a FRET-qPCR with DNA sequencing confirmed high <i>Chlamydia pecorum</i> loads (up to 1.1 × 10⁷ copies/swab). <i>Mycoplasma</i> testing was negative. Extended treatment with systemic and topical oxytetracycline led to gradual clinical improvement, with <i>C. pecorum</i> DNA declining over 22,000-fold and becoming undetectable after five weeks. This case represents the first documented report of <i>C. pecorum</i>-associated keratoconjunctivitis in goats in the United States. The findings underscore the diagnostic importance of molecular assays for detecting intracellular pathogens that may be missed by culture. The protracted treatment course highlights the therapeutic challenges posed by chlamydial infections due to their intracellular persistence. Additionally, the concurrent detection of <i>M. bovoculi</i> suggests the potential for mixed infections influencing disease severity. These results emphasize <i>C. pecorum</i> as an emerging pathogen of caprine ocular disease with implications for herd health and management.