Pannus

There is conjecture as to the term pannus as this is sometimes reserved for a condition of vascularization (appearance of blood vessels) on the white part only of the eye. Pannus in this case refers to, progressive, proliferative, chronic superficial keratitis (ongoing, spreading,long-standing, inflammation of the surface of the eye) which generally effects both eyes and spreads over the cornea (clear part of the eye). The condition starts as vascularization and pigmentation (pink-brown discoloration) at the lateral limbus (outside corner of the eye). It then extends slowly from the lateral, medial (inner margin), ventral (lower margin) and dorsal (upper margin) of the eye, in that order, to cover the entire cornea. White areas may appear in the cornea at the advancing edges of the lesion. Yellow-white fat deposits may also appear in this area. The condition can eventually lead to blindness. There is a recognized breed predisposition that includes the German Shepherd, Belgian Tervuren, Border Collie, Siberian Husky and the Australian Shepherd. Dogs normally develop the problem between the ages of 4-7yrs, although it can occur at any age.

Pannus is thought to be an immune-mediated problem, where the immune system (body's defense system) becomes over active and is triggered to attack its own body, in this case the cornea. The problem appears to be accelerated by increased exposure to the sun.
Diagnosis can be aided by microscopic examination of a scraping of the surface of the affected cornea to look for lymphocytes and plasma cells, two particular cells from the immune system that should not normally be present in large numbers.

There is no specific cure for pannus with the aim of therapy being to control the over reaction of the immune system. Cyclosporin and corticosteroids drops are generally used in the eye to reduce the inflammation. These drugs may be used singularly or in combination, depending on the individual dog’s response. Treatment will be required indefinitely especially during the warmer months of the year. Minimizing exposure to the sun is also advisable.