Chronic superficial keratitis

Chronic superficial keratitis (CSK), also known as pannus or Uberreiter's disease, is an inflammatory condition of the cornea in dogs, particularly seen in the German Shepherd. Both eyes are usually affected. The corneas gradually become pigmented and infiltrated by blood vessels, and the dog may eventually become blind.

Chronic superficial keratitis in a dog

Signs and symptoms

CSK is usually a bilateral progressive condition, however the lesions are not symmetrical nor are they painful. Signs include pigmentation and vascularization of the cornea (extension of blood vessels onto the cornea). It is usually first seen at the lateral (temporal) limbus (the junction between the cornea and sclera), although it eventually can extend from any part of the limbus to cover the entire cornea. Severe cases can cause blindness. Although CSK is usually identifiable by the appearance of the eye and the breed of the affected dog, cytology will reveal the presence of lymphocytes and plasma cells.[1]

Cause

CSK is immune-mediated in nature, characterized by an infiltration of white blood cells into the superficial stroma of the cornea. These cells are predominantly CD4-expressing T lymphocytes and to a lesser extent CD8-expressing T cells.[2] The CD4-expressing T-cells secrete gamma interferon, which causes expression of the major histocompatibility complex class II molecules in the cells of the cornea. These class II molecules cause further inflammation by interacting with the T cells and triggering an immune response.[3] Ultraviolet light is important in the genesis of the disease which is seen at higher prevalence at elevated altitude[4] and has a seasonal variation with most cases occurring in the summer. There is likely also a genetic component to the cause of CSK due to its predominance in certain breeds.

Treatment

Treatment of CSK is usually with topical corticosteroids or topical cyclosporine, but any treatment only controls and reduces the inflammation rather than providing a cure.[5] Other investigated treatments include pimecrolimus, a derivative of ascomycin that interferes with T cell activation and inhibits the production of inflammatory cytokines.[6] Strontium-90 radiation therapy is also used to treat CSK.[7] Canine sunglasses have also been used to help protect the eyes of dogs with CSK to prevent further damage from ultraviolet radiation.[8]

Epidemiology

Chronic superficial keratitis is most commonly seen in German Shepherds,[9] but it is also found in Belgian Tervurens, Greyhounds, Siberian Huskies, Australian Shepherds, and Border Collies.[10]

See also

References
  1. Gilger, B.C. (2006). "Ocular Cytology - Your Key to Immediate Ocular Diagnosis". Proceedings of the North American Veterinary Conference. Retrieved 2007-04-28.
  2. Williams D (1999). "Histological and immunohistochemical evaluation of canine chronic superficial keratitis". Res. Vet. Sci. 67 (2): 191–5. doi:10.1053/rvsc.1999.0329. PMID 10502491.
  3. Williams D (2005). "Major histocompatibility class II expression in the normal canine cornea and in canine chronic superficial keratitis". Veterinary ophthalmology. 8 (6): 395–400. doi:10.1111/j.1463-5224.2005.00412.x. PMID 16359362.
  4. Chavkin M, Roberts S, Salman M, Severin G, Scholten N (1994). "Risk factors for development of chronic superficial keratitis in dogs". J. Am. Vet. Med. Assoc. 204 (10): 1630–4. PMID 8050943.
  5. Sapienza, John S. (2002). "Corneal Diseases of Dogs and Cats". Proceedings of the 27th World Congress of the World Small Animal Veterinary Association. Retrieved 2007-04-28.
  6. Nell B, Walde I, Billich A, Vit P, Meingassner J (2005). "The effect of topical pimecrolimus on keratoconjunctivitis sicca and chronic superficial keratitis in dogs: results from an exploratory study". Veterinary ophthalmology. 8 (1): 39–46. doi:10.1111/j.1463-5224.2005.04062.x. PMID 15644099.
  7. Höcht S, Grüning G, Allgoewer I, Nausner M, Brunnberg L, Hinkelbein W (2002). "[Treatment of keratitis superficialis chronica of the dog with strontium 90]". Strahlentherapie und Onkologie. 178 (2): 99–104. doi:10.1007/s00066-002-0891-1. PMID 11942044.
  8. Thornton, Kim Campbell (2006-07-17). "Shades for Scruffy? Canine eyewear not just for being a doggie diva". NBC News. Retrieved 2007-04-28.
  9. Stanley R (1988). "Superficial stromal keratitis in the dog". Aust. Vet. J. 65 (10): 321–3. doi:10.1111/j.1751-0813.1988.tb14515.x. PMID 3058108.
  10. "Cornea". The Merck Veterinary Manual. 2006. Retrieved 2007-04-28.
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