A Comprehensive Guide to Pannus in Dogs

April 15, 2022 Written by: Aiden Doane

Photo used with permission from Bliss Animal Eye Care

Since releasing our original article about pannus in dogs, we've had a lot of dog owners tell us their stories about dealing with pannus in their own dogs. Although every story is different, there's one comment we hear over and over again: "I just wish I'd known what it was sooner so I could have taken precautions." We know the feeling -- our own goofball, Tuckerman (German Shepherd mix), has had pannus since he was two. So while many of us may be frustrated that we didn't know sooner, we can still help educate others and spread the word so pannus is as well known by dog owners as, say, looking for ticks. Let's get to work, but first, a disclaimer: if you at all suspect your dog might have pannus, make an appointment with your vet or a veterinary ophthalmologist to ensure you get the proper diagnosis. Pannus can easily be confused with numerous other eye conditions, all of which require different types of treatment, and the only way to be sure is to seek professional care.

canine eye with pannus diagram

What is pannus?

Pannus in dogs, also known as Chronic Superficial Keratitis (CSK), is an autoimmune disease that affects the cornea (the clear) part of the eye and, if left untreated, can eventually scar the eye so badly it can cause serious vision impairment or blindness.

OK, so what exactly is an autoimmune disease? Well, the purpose of your immune system (and a dog's immune system) is to keep you healthy -- it heals infections and tries to protect your body. But there are some diseases out there -- in fact, more than 80 are currently known, that are referred to as autoimmune diseases. They essentially trick your immune system into attacking healthy cells by mistake -- so instead of attacking bad cells, the immune system attacks normal, healthy cells instead. The immune system's job is to track all of its healthy cells so it knows when something foreign comes into the body, but in the case of autoimmune diseases, the system glitches up, causing unintentional damage to healthy parts of the body.

Unfortunately, there's no definitive answer for what causes autoimmune diseases. We'll look at some of the potential causes as we go, but the official scientific answer at this point is that we don't know why they occur.

So pannus/CSK is a progressive disease, but depending on a variety of factors such as genetics and UV exposure, it may progress at a slow or rapid rate, so you'll want to identify and begin treating it as quickly as possible.

While you'll most often hear of pannus being common in German shepherds, greyhounds, and a few other breeds due to a genetic predisposition, don't assume your dog can't get it. Pannus can occur in any breed and any size dog.

What causes pannus?

There is evidence that some breeds are genetically predisposed to developing pannus, such as German shepherds, border collies, and greyhounds, among others. We don't actually know what exactly causes autoimmune diseases, but we do know that pannus in dogs is not contagious. 

Vets and scientists alike agree that increased exposure to UV rays makes the disease worse and could be an initiating factor in the disease. Dogs living at higher altitudes tend to be more susceptible to the disease due to the increase in UV exposure.

There are also studies that suggest environmental allergens may cause a type of allergic reaction with some dogs' corneas. In addition, there are some holistic practitioners that treat pannus through diet, suggesting there could be a tie between food allergies and the progression of the disease, though this has not been scientifically proven.

How do I identify pannus in my dog?

Although it's helpful to be able to identify or at least suspect pannus to be the diagnosis of your dogs' eye condition, the only way to be sure is to seek professional care through a vet or veterinary ophthalmologist . Pannus can easily be confused with other eye problems such as Keratoconjunctivitis (also known as "dry eye"), according to Dr. Cassandra Bliss, who runs a veterinary ophthalmologist practice, Bliss Animal Eye Care, based out of Central Point, Oregon (disclaimer: we love Dr. Bliss and wrote a hunting article about her and her champion bird dogs here).

There are some common signs that you can look for in your dog that may point to a pannus diagnosis. Because the disease affects the cornea, there is usually a change in pigmentation where a cloudiness will develop and often contain visible blood vessels. With pannus, this change usually begins at the outside of the cornea, moving inward. Looking at a dog's face and imagining their eye as a clock, these changes will most often be noticeable at the 3 o'clock and 9 o'clock positions.

If you didn't already know, dogs have a third eyelid (we humans only have two) that serves multiple purposes from clearing mucus off the cornea to protecting the cornea to producing a third of dogs' tears. Looking closely at your dog's eye, you'll see this third eyelid in the bottom corner of the eye (see image below).


Dr. Bliss points out on her blog, "Reddening, thickening, and pigment loss of the third eyelid characterize a subclass of CSK [pannus], called plasmoma." Excessive mucus discharge from the eye may be a sign that your dog has plasmoma, so again, get it checked out by a professional.

Be especially diligent about checking your dog for any of these symptoms during the summertime or if your pup spends a lot of time outdoors. "I always see more cases during the summer," Dr. Bliss concurs. "UV light exposure definitely plays a role. I always examine my CSK [pannus] patients in the spring to see how they did over the winter and discuss any change in frequency for medications and again in the fall to make sure no worsening was noted over the summer so we can ensure good control of the disease."

Dogs that live and play at higher altitudes should also be monitored carefully. As noted in our previous pannus article, dogs that live or spend time outdoors above a few thousand feet who develop pannus can be much more difficult to treat. This doesn't mean you need to relocate to a lower altitude, but it does mean you may want to take additional precautions in addition to careful monitoring of your dog's eyes.

Should you notice any of the symptoms we've mentioned above in your dog, schedule an appointment with your vet as soon as possible. Without treatment, the immune system will continue to attack the cornea to the point where scar tissue develops and can then lead to severe vision issues, including blindness.

What are the different treatment options?

There is no cure for pannus or way to get rid of it, but there are several ways to treat the condition.

  • The most common treatment is through medications that keep the blood vessel growth and cloudiness under control. These anti-inflammatory medications commonly include corticosteroids, tacrolimus, or cyclosporine and are administered most often through eye drops, but can also be administered through ointments or even injections. While these medications have to be given for the lifetime of the animal, over time the amount can usually be decreased.
  • Shout out to us! Many vets are now recommending that Rex Specs be used in conjunction with medication as a way to keep the condition from worsening over time. See below for more information on dog owners who have used Rex Specs and seen a dramatic impact on the amount of eye drops necessary to keep pannus under control.
  • In the most severe cases, your dog may need surgery to decrease/remove the scarring and pigmentation in the cornea that is causing the vision impairment. Again, this will not cure the disease, and the condition will recur if other treatment measures are not continued after surgery.
  • There are some cases where a change in diet has reportedly helped slow down the progression of pannus in conjunction with conventional treatment (medication). In all of the cases we've read about, treatment includes an anti-inflammatory diet or looking at food allergens as a natural progressor to the disease. We're not experts, and you'll probably want to consult your vet about this, but here are a couple of references you can review:
    • Dr. Cathy Alinovi, serving pets in Indiana and Illinois (we have no connection to Dr. Alinovi)
    • Dr. Jeffrey Feinman, who suggests nutritional supplements as part of a homeopathic approach in an article for Dogs Naturally Magazine (we have no connection to Dr. Feinman)

Do Rex Specs really help prevent pannus?

We try to avoid shameless self-promotion of Rex Specs, but the truth is that we developed them specifically to try to combat pannus in our German Shepherd mix, Tuckerman. Since then, we've had numerous vets and dog owners report that they're an important tool in the prevention and treatment of pannus. Here are a few testimonials from customers who've bought our goggles as part of their treatment plan:

  • "Our GSD has pannus and all our vets have said that if we move out of elevation (Denver) the problem is solved. We are not going to move however, so the Rex Specs are necessary. Our ophthalmologist was thrilled at his one year checkup and said he wished all his clients were doing so well. Drops twice a day and 👓on whenever he's out during the day." - Jodi, from Colorado
    • "Johan now, a year after finding Rex Specs. Stlil has some staining but corneas are clear as glass and we've been able to cut back on the eye drops to once every 3 days (were twice to three times a day before Rex Specs). They really do make a difference. Thank you." - Cheryl
      • "I LOVE Rex Specs!! I won't lie, when I saw the price it took me a couple of days to decide. And I am so glad I bought them for my boy!!! The price doesn't seem high once you get them in the mail and see the quality. And once you put them on your dog for the first time, you'll wonder why you ever doubted them! I will have a pair of Rex Specs for every dog that comes into my life down the road. Lance can finally enjoy himself out in the sun, and I don't have to worry about his eyes getting sunburnt. Thank you a thousand times, Rex Specs K9, for making such a stellar product!" - Kaitlyn
      • "Three years ago, Kāne was diagnosed with atypical Pannus. Living in Colorado is especially tough since we have high UV levels and the higher elevation is an additional risk factor. Since Kāne's diagnosis I have tried several different types of eye protection but all of them fell apart easily and none fit him well. Kāne debuted [Rex Specs] in Deadwood last weekend and while he needs more practice jumping in them, he took to them easily and I was pleased with how they fit and stayed on during jumping. We also made sure that the spectators were told that these aren't just a fashion statement, even though he looks pretty darn handsome in them. I'm excited to start using them during our runs together and for general time outside. I'll also show them to Kane's ophthalmologist so they can pass the info onto other clients." - Heather, from Colorado
      • "We have been using your product for just about a year now. They were recommended to us by our dog's ophthalmologist because of lack of pigment in and around the eyelid. As a vision rehab worker I was all over this!!  We followed your protocol and after about 4 weeks Bogey was wearing the mirrored lens. The goggles are a great way for me to spread the word about eye health for not only us but for our dogs!" - Sharon

      Where can I find more information?

      For starters, talk to your vet to get as much information as you can on pannus. Second, if YOUR dog has pannus, let us know your story in the comment section below. Your experience can help others!! Here are a few more links if you're interested in diving deeper.

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