Pannus

Dear Dr. Jody:  Our three year old German shepherd, “Daisy”, has recently developed little pink patches of tissue on the surface of her eyes.  These patches do not seem to bother her, but they are gradually getting bigger.  What are they, and do we need to be concerned?

What you are describing sounds very much like a condition called pannus.  Pannus is a frustrating ocular condition that primarily affects German shepherds, however, other breeds such as greyhounds, huskies, dachshunds, and poodles can be predisposed.   

Pannus, also called chronic superficial keratitis, is a progressive immune-mediated inflammation of the cornea, which appears as plaques, or deposits, of pigment and granulation tissue on the surface of the eye.  These deposits start at the lateral, or outside edge of the cornea, and slowly spread and grow across the surface of the eye, sometimes involving other membranes including the conjunctiva and the third eyelid.  Fortunately, the disease is not painful, however, because it is chronic and progressive, it often does ultimately result in blindness as the pinkish plaques and dark brown pigment eventually cover the surface of the eye and do not allow light to penetrate the cornea.  Usually, both eyes are affected at the same time.

Pannus is considered to be hereditary to some degree, which explains why certain breeds are predisposed.  However, it is interesting to note that ultraviolet radiation is also believed to be a significant factor in its development.  And because dogs that live at high elevations are exposed to more ultraviolet radiation than dogs at low elevations, dogs in the Calgary and Cochrane area are especially predisposed. 

Because pannus is an immune-mediated disease, the treatment of choice is topical steroids such as prednisone or dexamethasone.  In more aggressive cases that do not respond significantly to the topical steroids, more costly products such as topical cyclosporine must be used.  These drugs are applied as drops to the eyes once or twice daily, unfortunately, forever.  The condition is like a runaway freight train.  It cannot be turned around, but we can slam on its brakes to some degree.  Treating the dog’s eyes daily with steroid eye drops limits the immune reaction that continues to occur, but it does not stop it completely.  

Within years, most affected dogs are severely visually impaired in both eyes, if not blind. 

Because UV radiation is believed to worsen the condition, affected dogs may benefit from wearing specially designed goggles – called “Doggles” – that prevent UV radiation from reaching the eyes.  Doggles act like sunglasses for dogs, and can be very helpful in limiting the progression of the disease when used in conjunction with the topical lifelong medication.   They can be purchased online in a wide array of fashionable colors, and for a very reasonable price.

Frustratingly, pannus is one of those conditions that veterinarians cannot cure.  With the owner’s dedication, however, we can significantly slow down the progress of this chronic but non-painful disease to ensure that the dog retains his vision for as long as possible.  And just think how proud your pooch will feel to be a trendsetter with his hip new eyewear!

Photo showing the pink plaque of tissue spreading across the cornea in a dog affected with pannus.  The green liquid is a fluorescent dye used to help diagnose the condition.  Photo used with permission by Dr. Kelli Ramey, Western Veterinary Specialist Centre.