Pannus in Dogs (Chronic Superficial Keratitis)

By Malcolm Weir, DVM, MSc, MPH; Ryan Llera, BSc, DVM; Ernest Ward, DVM

What is pannus?

Pannus or chronic superficial keratitis is an immune-mediated condition that affects the cornea or clear part of the eye. It occurs primarily in middle-aged German shepherd dogs or German shepherd mixes, and Belgian Tervurens, but other breeds may also be affected.

What are the clinical signs of pannus?

At first, a non-painful, elevated pink mass appears on the cornea, most commonly on the lateral or outer side. If you imagine the eye to be a clock face, the mass will often be found in the eight to eleven o'clock position on the pet's right eye, or the one to four o'clock position on the left eye. Both eyes are usually affected, but one may appear worse than the other. The third eyelid commonly appears thickened and inflamed.

As pannus progresses, the lesion will flatten and spread out, will become pigmented or dark in color, and scarring will spread over the cornea. A mucoid discharge may also be present. In advanced cases, sight loss may result due to the inability to see through the dark pigment covering the cornea. If the condition is not treated, the pet will become blind.

What causes pannus?

Pannus is thought to be a hereditary condition that develops as the pet ages. 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.

How is pannus diagnosed?

Diagnosis is based on medical history and clinical signs. Diagnostic tests include corneal staining with fluorescein dye, intraocular pressure (IOP) testing, and corneal or conjunctival scrapings. Many of these tests are often done to rule out other eye conditions.

How is pannus treated?

Treatment involves using topical corticosteroids (typically prednisolone or dexamethasone) or other immune-modulating drugs such as cyclosporine. On occasion, treatment will involve an injection of steroids under the conjunctiva.

More recent treatments include subconjunctival injection of long-lasting cyclosporin implants. Antibiotics are sometimes required in cases that have developed a secondary infection. Due to the influence of UV lighting on pannus, your veterinarian may suggest dog sunglasses (e.g., Doggles®) to provide extra protection.

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. It is important that you follow your veterinarian's instructions carefully and administer medications consistently. Regular check-ups and vigilance are imperative since the condition often relapses throughout life.

What is the prognosis for a dog diagnosed with pannus?

Most cases respond well to topical medications. Some dogs will require referral to a board-certified veterinary ophthalmologist for more aggressive treatments. In severe cases, surgery to remove the scar tissue associated with pannus may be recommended to improve the pet's vision. Failure to give the recommended medications as prescribed can make the condition worse.

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