Also known as chronic superficial keratitis, pannus is a progressive immune-mediated disease that affects the cornea (the clear part) of a dog's eye.
In a healthy dog's body, the immune system heals infections and protects the body from illness. Its purpose is to track the body's healthy cells so it's aware of when something foreign enters the bloodstream. Autoimmune diseases introduce a kind of glitch in the system. These illnesses trick the immune system into attacking healthy cells by mistake. So, instead of attacking "bad" cells, the immune system attempts to kill normal, healthy cells, causing damage to organs throughout the body.
Canine pannus occurs primarily in middle-aged German shepherd dogs or German shepherd mixes, as well as greyhounds and Belgian Tervurens. However, this disease can occur in dogs of any breed and size.
Causes of Pannus in Dogs
Unfortunately, autoimmune diseases do not have a definitive cause, but genetic predisposition can leave your dog more vulnerable to pannus.
How fast pannus progresses in your dog can depend on numerous factors, such as UV exposure, high altitude (if your dog spends a significant amount of time at altitudes over 4,000 feet) or genetics. This is why early diagnosis and treatment are so important.
Symptoms of Pannus
The first symptom you may notice is an elevated pink mass on the cornea, which will most often appear on the lateral or outer side before moving inward. If you imagine the eye as a clock face, the mass will often be found in the eight to eleven o'clock position on the right eye or the one to four o'clock position on the left eye. Cloudiness may also develop.
While both eyes are typically affected, one may appear worse than the other. You may or may not be aware that dogs have a third eyelid. Its purpose is to protect the cornea and clear mucus from the cornea, in addition to producing a third of a dog's tears. While the mass may not be painful, with pannus this third eyelid commonly appears thickened and inflamed. Note that reddening, thickening, and pigment loss on the third eyelid can be a subclass of pannus called plasmoma.
Symptoms of advanced pannus can include vision loss. Left untreated, scarring can worsen to the point that it causes severe vision impairment or blindness. Over time, the lesion will spread and flatten. You may notice it becomes pigmented or darkens in color, and the cornea takes on a scarred appearance. In advanced cases, your dog may experience vision loss due to their inability to see through the dark pigment covering the cornea. Without treatment, a dog will become blind.
Diagnosing Pannus in Dogs
When it comes to identifying and diagnosing pannus in dogs, your vet will review your pup's medical history and check for the clinical signs and symptoms mentioned above. Diagnostic tests may include:
- Corneal or conjunctival scrapings
- Intraocular pressure (IOP) testing
- Corneal staining with fluorescein dye
Many of these tests can help your vet eliminate other eye conditions as a potential cause of your dog's symptoms.
Prognosis & Treatment for Pannus in Dogs
Pannus can be managed, but not cured. The most common treatment for pannus in dogs is anti-inflammatory medication or topical immunosuppressive drugs to manage the growth of blood vessels and to control cloudiness. These medications commonly include cyclosporine, corticosteroids, or tacrolimus, and are most often administered via eye drops.
However, they can also be administered through ointments or injections. While your pet will likely be medicated for the rest of their lives, the amount you'll need to administer can usually be decreased over time. In rare cases, oral immunosuppressive medications are also prescribed.
In some cases, a change in diet combined with conventional medication may help to slow the progression of pannus. Your veterinarian can tell you whether any changes to your pet's diet are necessary.
In more severe cases, your dog may require surgery to decrease or remove scarring and pigmentation in the cornea that's causing vision impairment. Keep in mind that this will not cure the disease, and the condition will recur if other treatment measures are not maintained following surgery.
Since UV light exposure can play a role in the progression of this disease, careful monitoring through the spring and summer months is important. Depending on whether your pet's symptoms have worsened, changes in medications may be necessary to manage the condition. Dogs that live and play at higher altitudes should also be monitored carefully.
If you suspect your dog may have pannus, book an appointment with your veterinary ophthalmologist as soon as possible to obtain an accurate diagnosis. Pannus can be easily confused with many other eye conditions, all of which require different treatment methods. The only way to be sure your pup receives the right treatment is to seek professional veterinary care.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical or behavioral advice regarding pets. Please make an appointment with your vet for an accurate diagnosis of your pet's condition.