Title: Chronic superficial keratitis

{{Short description|Eye disease in dogs}}
[[Image:Canine pannus.JPG|thumb|Chronic superficial keratitis in a dog]]
'''Chronic superficial keratitis''' ('''CSK'''), also known as '''pannus''' or '''Uberreiter's disease''', is an inflammatory condition of the [[cornea]] in [[dog]]s, 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.

==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, [[cytopathology|cytology]] will reveal the presence of lymphocytes and [[plasma cell]]s.&lt;ref&gt;{{cite web | last = Gilger | first = B.C. | title = Ocular Cytology - Your Key to Immediate Ocular Diagnosis | work = Proceedings of the North American Veterinary Conference | date = 2006 | url = http://www.ivis.org/proceedings/navc/2006/SAE/306.asp?LA=1 | access-date = 2007-04-28 }}&lt;/ref&gt;

==Cause==
CSK is [[Immune-mediated disease|immune-mediated]] in nature, characterized by an infiltration of [[white blood cell]]s into the superficial stroma of the cornea.  These cells are predominantly [[CD4]]-expressing [[T cell|T lymphocyte]]s and to a lesser extent [[CD8]]-expressing T cells.&lt;ref&gt;{{cite journal |author=Williams D |title=Histological and immunohistochemical evaluation of canine chronic superficial keratitis |journal=Res. Vet. Sci. |volume=67 |issue=2 |pages=191–5 |year=1999 |pmid=10502491 |doi=10.1053/rvsc.1999.0329}}&lt;/ref&gt;  The CD4-expressing T-cells secrete gamma [[interferon]], which causes expression of the [[major histocompatibility complex]] [[MHC class II|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.&lt;ref&gt;{{cite journal |author=Williams D |title=Major histocompatibility class II expression in the normal canine cornea and in canine chronic superficial keratitis |journal=Veterinary Ophthalmology |volume=8 |issue=6 |pages=395–400 |year=2005 |pmid=16359362 |doi=10.1111/j.1463-5224.2005.00412.x|doi-access=free }}&lt;/ref&gt;  [[Ultraviolet|Ultraviolet light]] is important in the genesis of the disease which is seen at higher prevalence at elevated altitude&lt;ref&gt;{{cite journal |vauthors=Chavkin M, Roberts S, Salman M, Severin G, Scholten N |title=Risk factors for development of chronic superficial keratitis in dogs |journal=J. Am. Vet. Med. Assoc. |volume=204 |issue=10 |pages=1630–4 |year=1994 |pmid=8050943}}&lt;/ref&gt; 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 [[corticosteroid]]s or topical [[Ciclosporin|cyclosporine]], but any treatment only controls and reduces the inflammation rather than providing a cure.&lt;ref&gt;{{cite web | last = Sapienza | first = John S. | title = Corneal Diseases of Dogs and Cats | work = Proceedings of the 27th World Congress of the World Small Animal Veterinary Association | date = 2002 | url = http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&amp;PID=2647 | access-date = 2007-04-28 }}&lt;/ref&gt;  Other investigated treatments include [[pimecrolimus]], a derivative of [[ascomycin]] that interferes with T cell activation and inhibits the production of inflammatory [[cytokine]]s.&lt;ref&gt;{{cite journal |vauthors=Nell B, Walde I, Billich A, Vit P, Meingassner J |title=The effect of topical pimecrolimus on keratoconjunctivitis sicca and chronic superficial keratitis in dogs: results from an exploratory study |journal=Veterinary Ophthalmology |volume=8 |issue=1 |pages=39–46 |year=2005 |pmid=15644099 |doi=10.1111/j.1463-5224.2005.04062.x}}&lt;/ref&gt;  [[Strontium-90]] [[radiation therapy]] is also used to treat CSK.&lt;ref&gt;{{cite journal |vauthors=Höcht S, Grüning G, Allgoewer I, Nausner M, Brunnberg L, Hinkelbein W |title=[Treatment of keratitis superficialis chronica of the dog with strontium 90] |journal=Strahlentherapie und Onkologie |volume=178 |issue=2 |pages=99–104 |year=2002 |pmid=11942044 |doi=10.1007/s00066-002-0891-1|s2cid=22084291 }}&lt;/ref&gt;  Canine [[sunglasses]] have also been used to help protect the eyes of dogs with CSK to prevent further damage from ultraviolet radiation.&lt;ref&gt;{{cite web | last = Thornton | first = Kim Campbell | title = Shades for Scruffy? Canine eyewear not just for being a doggie diva | work = NBC News | date = 2006-07-17 | url = https://www.nbcnews.com/id/wbna13820336 | access-date = 2007-04-28 }}&lt;/ref&gt;

==Epidemiology==
Chronic superficial keratitis is most commonly seen in [[German Shepherd]]s,&lt;ref&gt;{{cite journal |author=Stanley R |title=Superficial stromal keratitis in the dog |journal=Aust. Vet. J. |volume=65 |issue=10 |pages=321–3 |year=1988 |pmid=3058108 |doi=10.1111/j.1751-0813.1988.tb14515.x}}&lt;/ref&gt; but it is also found in [[Belgian Tervuren]]s, [[Greyhound]]s, [[Siberian Husky|Siberian Huskie]]s, [[Australian Shepherd]]s, and [[Border Collie]]s.&lt;ref&gt;{{cite web | title = Cornea | work = The Merck Veterinary Manual | date = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/30109.htm | access-date = 2007-04-28 }}&lt;/ref&gt;

==See also==
* [[Uveal cyst]]
* [[Meibomian cyst]]

==References==
{{Reflist}}

[[Category:Dog diseases]]