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C. M. H. Colitz, M. S. Renner, C. Manire, T. Schmitt, L. Croft, C. Dold, L. Dalton, J. Olds, B. Doescher, E. Gehring; Characterization of "Sea Lion Keratitis" in Captive Zalophus Californianus: Descriptive Analysis. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5722.
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© ARVO (1962-2015); The Authors (2016-present)
To describe three consistent, progressive presentations of keratitis in California sea lions (Zalophus californianus).
All animals underwent a complete ophthalmic examination and eyes were photographed.
Two-hundred eighteen eyes from 109 animals (64 males/45 females) were examined. Average age was thirteen years. Sixty-five animals were affected (59.6%), 59 had bilateral and 6 had unilateral involvement. Category one includes 68 eyes with small, white and focal lesions at the dorsotemporal paraxial cornea; five cases were unilaterally involved. Category two includes 23 eyes with larger diffuse white corneal opacities that encompassed 5 to 20 % of the dorsotemporal paraxial cornea. All had bilateral involvement. Category three includes 29 eyes with lesions encompassing over 20% of the cornea with stromal involvement; one animal had unilateral involvement. Most cases had documented bacterial and/or fungal infections while in stages 2 or 3.
The initial cause of the stage one lesion is unknown. Possible etiologies include virus, exposure to UV/sunlight, and trauma. Viral testing has been inconclusive, the consistent location makes trauma unlikely, though this location is also the only site where all three eyelids come together and may leave it vulnerable during squinting. It appears that the recurrent focal initial lesion causes the cornea to become susceptible to secondary infections and this is likely exacerbated by excessive sun exposure which weakens and thins the corneal stroma. Further investigation into the primary cause as well as an imbalance of the local surface immune system will be pursued.
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