Description

Pannus is an infiltration of the corneas and/or third eyelids with

certain white blood cells, blood vessels, and brown pigment. It

is also called chronic superficial keratitis . The German shepherd

dog is predisposed to the condition. It may occur sporadically in

other breeds, such as the greyhound, Rottweiler, golden retriever,

Belgian tervuren, border collie, and others.

Causes

The disease is probably an immune-mediated condition, which is

an inflammation that is induced by an abnormal immune response.

Pannus is aggravated by ultraviolet radiation and pollution.

Clinical signs are most severe in dogs residing at high altitudes or

in environments with high levels of pollution.

Clinical Signs

Both eyes are typically affected. A red-gray film starts at the 4 and

8 o’clock positions and spreads across the cornea to meet in the

middle. If untreated, the entire cornea may become covered, with

loss of vision. With time brown (melanin) pigment invades the

cornea and may persist despite treatment.

With the third eyelid form of the disease (also known as plasmoma),

the leading edge and front surface of the third eyelids

become thickened, red, depigmented and irregular. Plasmoma

may occur alone or with the corneal disease.

Diagnostic Tests

Diagnosis is usually made by close examination of the corneas and

third eyelids. Additional testing for dry eye and corneal ulcers is

usually done. Scrapings may be submitted for microscopic analysis

(cytology) to identify the type of white blood cells present,

which are usually lymphocytes and plasma cells. Other causes of

corneal cloudiness must also be ruled out.

Topical steroid and cyclosporine medications are the most common

therapies used for pannus. In mild to moderate cases, topical

steroids may be used alone. In severe cases, topical steroids may

be combined with a steroid injection into the adjacent conjunctiva

or with topical cyclosporine. For severe, refractory cases of pannus

with significant loss of vision, beta radiation or cryotherapy

(freezing of the cornea) may be considered.

Although corneal ulcers are uncommon with pannus, topical

antibiotics are usually administered if they are identified.

Follow-up Care

Periodic recheck visits are used to assess response to treatment

and to make adjustments in the frequency and type of medications

administered. If the disease does not respond to one type of

steroid, it may respond to another or to a combination of steroids

and cyclosporine. Because topical steroids are usually needed

long term, the cornea is also monitored for ulcers with fluorescein

staining.

The goal of therapy is to clear the cornea of the pink-gray film

and then attempt to improve any pigmentation. Once the active

pannus has receded, the frequency of medications is decreased to

the lowest amount that keeps the condition in remission. Notify

your veterinarian immediately if you see any worsening of the film

in the cornea or any onset of pain (squinting or increased tearing).

If the eye becomes painful while a topical steroid is being given,

stop the drug until the eye can be re-examined.

Prognosis

Pannus and plasmoma can often be controlled but are rarely cured,

especially in German shepherd dogs. Treatment is usually needed

for the life of the dog. Active pannus may respond quickly or

slowly, but it usually does recede with appropriate therapy.

Corneal pigmentation can be very difficult to treat and may

persist. It is much easier to prevent corneal pigmentation by early

intervention and treatment than it is to get rid of the pigment once

it is in the cornea. After the pannus has receded, the cornea may

be left with mild, cloudy scarring or spots of lipid deposits. These

latter conditions do not usually affect vision, but vision can be

severely affected by pigmentation.

Vigilant monitoring is required to detect recurrences. Many

cases of pannus flare up, sometimes at the same time each year.

In some geographic areas, flare-ups are more common during the

summer; in others, recurrences are more likely during the winter.

Pannus almost always recurs if medications are stopped for any

length of time, and the recurrence can be more difficult to treat

than the original condition.

 

Treatment Options