Pannus in dogs (chronic superficial keratitis) is an immune-mediated condition that causes the surface of both of a dog’s eyes to become cloudy and pinkish to brownish. Integrative veterinarian Dr. Julie Buzby discusses the causes, symptoms, diagnosis, treatment, and prognosis for pannus, so dog parents know what to expect.
There are many types of eye diseases in dogs that can appear rather unsightly (no pun intended). Pannus is no exception. However, one of the things that sets pannus apart from many other diseases is the fact that although the eyes look like they would be extremely painful, they typically aren’t.
What is pannus in dogs?
Pannus is a condition where grey, pink, and/or dark brown discoloration starts to spread across the surface of both eyes. It usually begins at the border of the cornea, further from the nose, and progresses inward. But in some cases, pannus starts on the corneal border closer to the nose instead. While it isn’t painful, pannus can obscure a dog’s vision when it is severe.
The term pannus comes from the Latin word for “rag” or “cloth.” This likely refers to the way a dog’s corneas become cloudy. Pannus is also known as chronic superficial keratitis (CSK), with the term keratitis referring to inflammation of the cornea.
In about 70% of dogs with pannus, the dog’s third eyelid (the triangle of tissue resting against the eyeball in the inner corner of the eye) may become thickened, red, and bumpy, too. This is called a plasmoma.
What causes pannus in dogs?
Current evidence suggests that pannus is an immune-mediated condition. In other words, the dog’s immune system is attacking healthy cells in the cornea and third eyelid.
Ultraviolet (UV) exposure, such as from sunlight, is believed to exacerbate the condition by increasing the amount of an inflammatory mediator present in the corneal cells. Spending time at high altitudes can raise the risk of canine pannus, too. This is probably because higher altitudes lead to more UV light exposure.
Finally, there may also be a hereditary link, especially in German Shepherds. A study in Veterinary Immunology and Immunopathology that explored the genes associated with pannus in German Shepherd dogs supports that theory.
Which dogs tend to develop pannus?
Pannus most commonly affects German Shepherds (and German Shepherd mixes). But it can also occur in Greyhounds, Australian Shepherds, Belgian Shepherds, Border Collies, Rottweilers, Rhodesian Ridgebacks, and Siberian Huskies.
Most dogs are five to eight years old when they start showing symptoms. However, when pannus affects younger dogs, it tends to be more severe and more challenging to treat.
What are the symptoms of pannus in dogs?
Pannus affects the cornea and sometimes the third eyelid. Unlike some other diseases of the cornea that start in one eye, pannus affects both eyes at the same time.
Early on, the changes can be more subtle and just involve the edge of the cornea. But as pannus progresses, more and more of the cornea will become discolored and opaque.
Early signs of pannus in dogs
When pannus is just starting and is still mild, dog parents might notice signs such as:
- Hazy, white, or gray areas on the outer (or occasionally inner) edge of the cornea: This sort of cloudy eyes in dogs can make it difficult to see the iris (colored part of the eye).
- Slightly raised tissue on the surface of the eye: When viewed at an angle, you may notice that the discolored area on the cornea sticks up slightly.
- Pinkish red tint to some of the abnormal areas: Vascularization (growth of blood vessels) may give some areas a pink to blood-red appearance.
- Eye discharge: Mucoid discharge may or may not be present.
More severe or late-stage symptoms
Left unchecked, the immune system will continue to attack the cells of the cornea and potentially target the third eyelid, too. Thus, more severe or later-stage presentations of pannus in dogs include:
- Generalized corneal pigmentation: There may be a brown to black discoloration of much of the cornea.
- Pink “film” adhered to the surface of the cornea: The blood vessels may spread across the entire cornea, giving it a pinkish-red appearance.
- Changes to the third eyelid: The dog’s third eyelid might become thickened, bumpy, and very red instead of its normal pink color. Third eyelid involvement usually goes hand-in-hand with corneal changes. But there are some situations where a dog might have an abnormal third eyelid, yet a normal-looking cornea.
- White specks at the edge of the abnormal area: Lipid deposits may show up as white spots at the leading edge of the discoloration (the portion that is advancing across the cornea).
- Loss of vision: Sometimes the pigmented tissue covers all of both corneas, making it difficult for the dog to see. However, in milder cases, vision is typically unaffected.
Head to the vet
If you are seeing some of the symptoms above, make a veterinary appointment. Pannus is slowly progressive and not an emergency, but it is still ideal to start treatment sooner rather than later. (Other eye conditions can turn seriously quickly, though. When in doubt, call your vet for advice or make an emergency vet visit.)
How will the vet diagnose your dog with pannus?
At the appointment, the vet will gather a history and perform a physical exam. Then he or she will focus on the eyes. Often, the veterinarian can diagnose a dog with pannus based on the appearance of the surface of the eye and third eyelid. This is especially true when the dog is also a breed predisposed to pannus.
However, your veterinarian may recommend eye tests to rule out other conditions. They could include:
- Fluorescein eye stain to look for corneal ulcers in dogs
- Schirmer tear test to rule out dry eye in dogs (keratoconjunctivitis sicca)
- Tonometry to evaluate intraocular pressure, which is abnormal in glaucoma in dogs or uveitis in dogs
There may also be situations where your vet refers your dog to a veterinary ophthalmologist. Having a veterinary specialist’s opinion can be helpful when your vet finds some unusual changes on the exam or your dog isn’t responding to treatment as expected.
What is the treatment for pannus in dogs?
Unfortunately, there is no specific cure for pannus in dogs. Instead, treatment for canine pannus focuses on resolving corneal abnormalities and then using long-term therapy to keep pannus in remission.
Topical steroids and immunosuppressants
Topical corticosteroids are the most common first-line treatment plan for pannus. On their own, they can greatly improve the appearance of the cornea and third eyelid in mildly affected dogs. But for more moderate to severe cases, the vet will likely combine a steroid with a topical immunosuppressive medication like cyclosporine.
At first, you will generally need to give your dog eyedrops every 6 to 12 hours (two to four times a day). This could be the case for weeks or sometimes months. However, once lesions resolve, the vet will taper down to the lowest dose of topical steroid or immunosuppressant that keeps the pannus under control.
Subconjunctival steroid injections or cyclosporine implants
Occasionally, there may be a dog who doesn’t respond to topical therapy or is very challenging to medicate. In those situations, veterinary ophthalmologists may be able to inject a steroid or place a topical cyclosporine implant under the conjunctiva. Typically, those treatments will need to be repeated every 6 to 12 months.
Minimizing UV light exposure
Since UV light worsens pannus, it is ideal to keep dogs with pannus inside during the day, especially during the summer months when there are more daylight hours. If your dog needs to be outside, be sure to provide shelter out of the sun. You can also consider having your dog wear UV-blocking goggles, such as Doggles®, in high-altitude or high-sunlight conditions.
Are there any natural remedies for pannus in dogs?
There are no effective natural remedies for pannus that will resolve the condition. However, you can consider using some supplements to help support your dog’s eyes.
Veterinary ophthalmologists sometimes recommend the supplement Ocu-GLO® for dogs with pannus or other eye conditions. It contains a blend of antioxidants and ingredients that are important for eye health.
Alternatively, omega-3 fatty acids for dogs can provide beneficial anti-inflammatory effects. Ocu-GLO and omega-3 supplements are not intended to take the place of steroids and immunosuppressants, though.
What is the prognosis for pannus in dogs?
With long-term treatment, the prognosis for dogs with pannus can be good, especially for dogs who live in areas with lower UV light. However, it can be more challenging to manage pannus in dogs who live in places with more UV exposure. Additionally, discontinuing treatment typically causes pannus to return. Thus, dog parents need to be prepared for lifelong administration of eye drops.
Typically, during treatment, the thickened grey to pink areas will resolve more quickly. However, it can take weeks or months for the brown pigmentation to go away, and sometimes a portion of it may remain permanently.
Consequences of untreated pannus
Lack of treatment (or stopping treatment) can result in irreversible changes such as cloudiness of the eyes and subsequent loss of vision. Plus, when left untreated, pannus has the potential to cause progressive destruction of the third eyelid. Sadly, there are also reports of ocular cancer (squamous cell carcinoma) developing in dogs with untreated chronic pannus involving the third eyelid.
Is pannus preventable?
Since pannus in dogs is an immune-mediated condition that may have a genetic link, it isn’t possible to prevent it entirely. However, if you have a dog who is prone to pannus (like a German Shepherd) and you live or frequently visit somewhere with higher levels of UV light, it may be a good idea to use UV-blocking goggles and keep your dog inside during peak UV light times.
This isn’t necessarily going to stop your dog from developing pannus. But it can’t hurt and may even help slow the development of pannus.
Work with your vet
Pannus (chronic superficial keratitis) in dogs can look pretty terrible, but thankfully, it isn’t painful, and it responds well to long-term therapy in many cases. If your dog gets diagnosed with pannus, the best thing you can do is to work closely with your veterinarian and follow his or her instructions.
In time, the eye drops, Doggles, or other measures will become part of your dog’s routine. And your dog’s eyes should be looking much better.
Has your dog been diagnosed with pannus?
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