Pannus (Chronic Superficial Keratoconjuncitivitis) is an inflammatory condition that can involve the cornea and/or third eyelid (nictitating membrane) of the dog.  

Causes of Pannus

The exact cause is unknown.  Although it can occur in any breed of dog, this condition is most commonly seen in the German Shepherd Dog and the Greyhound.  The condition can be seen in dogs of any age.  Other factors considered important include living in high elevation (above 4000 feet above sea level) and prolonged exposure to sunlight (UV light - ultraviolet radiation).

This condition is considered to be an immune-mediated disease.  An immune-mediated disease is one in which the immune system becomes overactive against normal proteins or cells of the body.  In this condition, inflammatory cells, particularly lymphocytes and plasma cells, attack the cornea and/or conjunctiva of the eye.

Signs of Pannus

Depending on the extent and severity of the condition, the following may be seen:

  • red eye
  • mucoid discharge from the eye
  • irregular appearance to the surface of the eye
  • clouding on the surface of the eye
  • scarring in the cornea
  • pain manifested by rubbing or squinting of the eye
  • pigmentation in the cornea
  • loss of vision
How is Pannus Diagnosed?

The condition may be suspected based on the appearance of the eye - particularly in the breeds that are predisposed to this condition. The condition must be differentiated from other conditions that also result in inflammation, scarring and pigmentary changes in the cornea including KCS (keratoconjunctivitis sicca), and eyelid abnormalities leading to exposure problems or irritation (ectropion, entropion, etc.).
Tests that are generally performed to assess patients with these signs include a Schirmer Tear Test to measure tear production (rule out KCS) and a Fluorescein Stain test to assess the cornea for ulceration. Additionally, a topical anesthetic may be applied to the eye and a gentle scraping performed over the affected area of the eye to obtain a sample. This sample is then examined under the microscope to confirm the presence of inflammatory cells. The diagnosis is generally confirmed by considering the findings of these tests coupled with the examination findings.
Treatment of Pannus

Treatment involves suppressing the local immune response. In the vast majority of patients, this can be successfully accomplished with topical medication. Treatment generally includes the use of a cortisone-containing anti-inflammatory. A topical immunosuppressive medication containing cyclosporine or tacrolimus is often used in conjunction with topical steroids to help control inflammation and reduce pigmentation in the cornea.
It's important to realize that this condition is generally not curable. Rather, the goal is to control the disease over the life of the affected dog. This is a chronic condition that, if untreated or if not aggressively and successively managed, can quickly lead to blindness.
Frequent medicating is initially prescribed (medication applied to the affected eye up to 4 times daily). As a positive response to medication is observed, the frequency of medicating may be slowly tapered to the lowest level necessary to control the condition. This requires periodic follow-up examinations of the individual.  
The Prognosis

The prognosis is generally good for controlling the condition if the caretaker is vigilent and compliant in applying medications at the prescribed frequency and keeping up with follow up examinations.
In severe or resistant cases, other routes of anti-inflammatory medication administration may be recommended.