What is pannus?
Chronic superficial keratitis, or pannus, is a progressive, inflammatory disease of the canine cornea. It is
potentially vision threatening due to the development of dense corneal blood vessels, scarring, and pigmentation, as well as infiltration of “fleshy” granulation tissue. Typical pannus usually begins at the temporal aspect of cornea closest to the ear and moves inwards, and in severe cases, it can cover the entire cornea leading to blindness.
What causes pannus?
The exact cause is unknown, but current evidence suggests that it is an immune-mediated disease. Risk factors include exposure to ultraviolent light, high altitude, and breed. Dogs living at higher altitudes with increased exposure to ultraviolent light are almost 8 times more likely to develop pannus than dogs at lower altitudes. It is thought that sunlight modifies the cells in the cornea causing an autoimmune reaction. The breeds most commonly affected
are German Shepherds, Shepherd crosses, and Greyhounds, but it can affect any dog breed.
How is pannus diagnosed?
A complete ophthalmic examination by a veterinary ophthalmologist is typically all that is needed to make a diagnosis of pannus. A diagnosis of pannus is made by a trained eye who can differentiate it from other diseases that cause chronic corneal irritation, such as pigmentary keratitis and dry eye.
How is pannus treated?
Pannus cannot be cured, but it can be controlled with a combination of topical corticosteroids (prednisolone acetate or dexamethasone) and immunomodulatory medications (cyclosporine or tacrolimus). These medications are used to reduce inflammation and to suppress the abnormal immune
reaction in the cornea. With treatment, the blood vessels and granulation tissue often resolve, while scarring and pigmentation will likely improve but may not resolve completely. If medical management is not successful, a keratectomy, or surgical removal of the superficial layer of the affected cornea, may be discussed as a treatment option.
What is the prognosis for pannus?
Prognosis is dependent on many factors, including age of onset, breed, and altitude, and the majority of dogs respond to medications. German Shepherds diagnosed at a younger age (1-5 years of age) tend to have a more rapidly progressive and aggressive form of the disease. Dogs living at higher altitudes may also have a more severe form of the disease and be harder to treat. Greyhounds, on the other hand, tend to affected at a younger age and have a mild form of the disease. Regardless of age or breed, reducing UV light exposure, by providing shelter on
sunny days or even using canine sunglasses, may be helpful in dogs with pannus. It is of utmost importance to understand that this disease requires diligent lifelong therapy and follow-up examinations with your ophthalmologist.