Pannus in Dogs: Symptoms, Causes, and Treatment

What Is Pannus in Dogs?

Pannus—also referred to as chronic superficial keratitis—is a non-painful eye condition in dogs that affects the cornea.

The cornea is the thin outer layer of the eye that provides protection and focuses light so that dogs can see. In most dogs who have pannus, both eyes are affected.

German Shepherds, Siberian Huskies, Australian Shepherds, and sighthounds have an increased risk of developing this condition, likely due to genetics. It’s most common in middle-aged dogs but tends to be most severe in younger dogs or those who live at high altitudes, due to increased ultraviolet (UV) light exposure.

Pannus in dogs occurs when the immune system’s inflammatory cells settle onto the cornea and form small, raised bumps alongside blood vessels.

These abnormalities first develop on the edges of the cornea and spread inward. The condition can range in severity depending on the dog’s age as well as environmental factors. In chronic cases, the cornea becomes darker in color and scarred.

Pannus is a slowly progressive disease that, if left untreated, can cause blindness in dogs.

While pannus is not considered a medical emergency, it’s important for dogs to receive treatment promptly to preserve vision and improve their response to treatment.

Symptoms of Pannus in Dogs

Symptoms of pannus in dogs may include:

• Raised bumps on the cornea

• Blood vessels spreading across the cornea

• A darkening in the color of the cornea

• Red and inflamed eyes

• Eye discharge, such as mucus

• Squinting

• Pawing at the eyes

• Blindness

Causes of Pannus in Dogs

Chronic superficial keratitis is an immune-mediated condition.

This means that a dog’s immune system inappropriately attacks its own body—in this case, the cornea—resulting in inflammation and progressive damage.

There may also be an underlying genetic component, as specific breeds, primarily German Shepherds, have a higher incidence of the disease.

How Veterinarians Diagnose Pannus in Dogs

A veterinarian will start with a thorough physical exam to check the dog’s overall health.

A complete eye exam will be done, which can identify changes to the cornea consistent with pannus. Typically, this is enough to diagnose the disease, but other tests may be done to rule out other eye conditions that can cause similar symptoms.

These tests may include:

• Schirmer tear test: This test measures tear production in the eyes. When tear production is reduced, eyes can become red and inflamed and produce a mucoid discharge.

• Fluorescein stain: Using a green fluorescein stain, a veterinarian can detect corneal ulcers, which can develop due to trauma or underlying disease.

• Tonometry: This test is used to measure eye pressure, which can be abnormal in response to diseases, such as glaucoma or uveitis.

Pet parents should discuss with their veterinarian when symptoms started and any medications the pet is currently taking.

Treatment of Pannus in Dogs

Treatment of pannus in dogs consists of topical immunosuppressive medications.

They are generally applied to a dog's eyes up to four times daily and may be used alone or in combination, depending on the dog’s needs.

Options may include:

• Corticosteroids, such as dexamethasone or prednisolone

• Cyclosporine

• Tacrolimus

Severe cases of pannus may benefit from steroid injections beneath the conjunctiva (the pink tissue surrounding the eye). Less commonly, surgery may be beneficial to improve vision.

German Shepherds who are diagnosed at a young age generally have pannus that is less responsive to treatment, as these cases tend to be more severe.

Pet parents should be aware that the condition can be managed but not cured. Treatment is required for the remainder of the dog’s life.

Some cases may require referral to a veterinary ophthalmologist for more advanced treatment options.

Recovery and Management of Pannus in Dogs

While pannus in dogs is treatable, it's not curable.

Dogs must continue to receive treatment for the remainder of their lives to keep the disease from progressing. If caught early, response to treatment is generally good.

Dogs living at lower altitudes have less severe disease and respond more favorably as well.

Most affected dogs have noticeable improvement with prompt treatment, but the time frame varies in each case.  

The goal for treatment is to use the smallest dosage of medication to keep symptoms at bay. Ideally, dogs would require only one topical medication long-term, such as tacrolimus or cyclosporine, but it may be necessary to continue a combination of these in some dogs.

Pet parents should follow the veterinarian’s instructions closely regarding medications and bring their dog to all follow-up appointments to ensure the disease is controlled with the current treatment plan.

Prevention of Pannus in Dogs

Most cases of pannus are not preventable, because they are thought to be immune-mediated or inherited.

However, dogs who spend time at high altitudes have a higher likelihood of developing this condition due to increased ultraviolet light exposure; therefore, protecting a dog’s eyes from UV exposure and keeping them indoors when the sun is at its peak can reduce the risk of disease.