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Does My Pug Have Pigment Keratopathy?

Pug dogs are known to have several eye diseases, which is common in their breed. The main health concerns are pigmentary keratitis and keratoconjuntivitis sicca. Cataracts, trichiasis, progressive retinal atrophy and entropion are also often seen in Pugs.

Pigmentary keratopathy was previously known as pigmentary keratitis, and is a serious condition causing blindness if it is not caught in the first stages and immediately treated. Young to middle aged Pugs develop Pigmentary keratopathy. This disease resembles getting mud on the windshield of your car in small amounts, you are still able to see, but if the entire windshield is covered it makes you completely blinded. The cells taking on brown pigmentation are losing their normal transparency. In the beginning a red patch is noticeable that include blood vessels and dark pigmentation which is spread across the surface of the eye inflaming the cornea. The cornea is the transparent structure at the front of the eye which is clear when it is healthy and normal. The cause is not known but it seems to be associated with dry eye, environmental irritants like wind or dust. Entropian which is a congenital defect of the eyelids that is most common in dogs. This is due to the eyelids rolling inward making the hairs on the eyelids rub against the eyeball, causing injury or irritation that is noticeable by the dog squinting and his eyes tearing. Surgery can be a solution to this problem.

In Pigmentary Keratopathy, a Pugs normal eye has a crystal clear cornea with no signs of any impairment to his vision when you look into the inside of his eye. When the eye is mildly affected you will see grey discoloration and brown discoloration beginning at the inside of the cornea and see that it has progressed to the center of the cornea. In moderate to severe cases of pigmentary keratopathy your Pugs eye will show the extent of increased density of the pigment moving more towards the center of the cornea and the pupil will not be easy to see into the inside of the eye. This will ultimately impair his vision.
Pigmentary keratopathy has no treatment available to completely reverse this disease at this time. It is very hard to remove the pigment after it has covered the cornea. To prevent the pigment amount to decrease on the cornea and help it not to spread the use of two eye drops known as cyclosporine A (CSA) and tacrolimus are now available. These medications influence the way the immune system reacts on the surface of the eye. Changing the pigmentation of the cornea and how these medications are able to accomplish this, is still unknown. These medications have to be used for the entire life of your dog, or the pigmentation will get worse. Dry eye known as keratoconjunctivitis sicca or KCS will also benefit by these medications.

Steroids such as prednisolone or dexamethasone are medications that are also used for pigmentary keratopathy. The immune system is suppressed by steroids that are a different mechanism than tacrolimus or CSA. The use of steroids has been found to cause infections on the surface of the eye. The conjunctiva which is the white surface of the eye can be injected also with steroids.

The pigment can be removed by surgery, but it is not a long term solution since the pigment grows back. The inside of the lower eyelid that rubs on the surface of the eye can be altered surgically slowing down the growth of pigmentary keratopathy. Transection of the medical canthal ligament, modified Hotz-Celsus and medial canthoplasty are techniques used in surgery.

Photo credit: Zero Pennyworth/Flickr