Pannus, also known as chronic superficial keratitis (CSK), is an immune-mediated condition that affects the cornea or clear part of the eye in dogs. It is believed to be a hereditary condition that develops as the pet ages, and breeds such as German shepherds, Belgian shepherds, and border collies are most affected, but pannus can occur in any breed. Predisposing factors such as increased exposure to ultraviolet light or living at high altitudes may contribute to the development of pannus and certainly can exacerbate the condition. The clinical signs of pannus include visible corneal and third eyelid lesions, ocular discharge, and redness of the eyes. Unless pannus affects both eyes severely, it does not have an effect on vision; however, if left untreated, there can be severe opacification of the cornea along with destruction to the third eyelid. Pannus is diagnosed through a complete eye examination by a veterinarian or veterinary ophthalmologist. Treatment will not cure the condition but will halt the progression and may reverse some of the changes. The treatment of pannus is for life, and it is important to follow the veterinarians instructions carefully and administer medications consistently. Regular check-ups and vigilance are imperative since the condition often relapses throughout life. Treatment options include topical "anti-rejection" drugs such as Tacrolimus or Cyclosporine, topical steroids, and reduction of exposure to ultraviolet radiation.