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Pannus

Issue Description
An inflammatory condition of the cornea in dogs.
Other Names
Chronic Superficial Keratitis, CSK, Uberreiter's Disease


Causes
The cause of pannus is believed to be an immune-mediated inflammation of the cornea that is made worse by external factors. Exposure to ultraviolet radiation and environmental pollution increases the severity of the condition. Dogs that live in areas of extensive sunlight, especially at high elevations tend to have the worst clinical signs. Pannus is not painful, but advanced cases may lead to blindness. Pannus occurs only in dogs. Most affected dogs are middle-aged, but the disease can develop in young adult dogs.

Breeds Affected
Pannus is generally known as a German Shepherd Dog eye disease but has also been seen in the Belgian Tervuren, Border Collie, Greyhound, and Siberian Husky.

Symptoms
Initially, redness, ocular discharge and brown pigment may be seen in the conjunctiva (white tissue of the eye). White infiltrates made up of inflammatory cells then invade the clear cornea. Next blood vessels invade the cornea. Finally pink connective tissue grows into the cornea and later becomes brown. In a small number of cases, two other symptoms may occur either alone or together. A thickening, redness, depigmentation and lumpiness of the third eyelid may occur. This is called a plasmoma. The other condition which may occur is chronic, erosive ulceration of the lower eyelid near the inner and outer corners of the eye. Pannus is uncomfortable to the dog. When treated adequately, your pet can be free of this irritation even though the corneas may not clear up completely.

Diagnosis
CSK is usually a bilateral progressive condition. 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.

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. Other investigated treatments include pimecrolimus, a derivative of ascomycin that interferes with T cell activation and inhibits the production of inflammatory cytokines. Strontium-90 radiation therapy is also used to treat CSK. Canine sunglasses have also been used to help protect the eyes of dogs with CSK to prevent further damage from ultraviolet radiation.

Dogs
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