Corneal Dystrophy in Dogs

Corneal endothelial dystrophy is a primary, inherited, bilateral (both sides), often symmetrical condition of the cornea that is not accompanied by corneal inflammation or systemic disease. It involves a malfunction of the inner layer (endothelium) of the cornea that is responsible for keeping the cornea dry and clear by pumping fluid from the cornea into the front chamber of the eye. With endothelial dystrophy there is a premature degeneration and failure of this pumping mechanism.

Corneal endothelial dystrophy is seen in dogs, and is known to occur in the Boston terrier, Chihuahua, and miniature dachshund. It also affects young domestic shorthair and Manx cats, although it is rare in cats.

The age of onset for this condition is quite variable. In the Boston terrier it may occur between 5-9 years of age, in the Chihuahua between 6-13 years of age and in the dachshund between 8-11 years of age.

What to Watch For

Change in color. Endothelial dystrophy results in water retention (edema) in the cornea. As the cornea becomes edematous, it turns a milky blue-white color. This color change often begins in one area of the cornea first, and then spreads to involve the whole cornea.

Ulceration and inflammation. As the cornea becomes more edematous and opaque it is prone to ulceration and inflammation. 

Squinting and tearing. These secondary conditions may cause the eye to be red or painful (squinty and tearing).

Diagnostic Tests

A complete eye examination is required to rule out other, more common causes of corneal edema. Endothelial dystrophy is rather rare, and other diseases of the eye (such as glaucoma, trauma, anterior uveitis, lens luxations, endothelial degeneration) are more likely to cause corneal edema. 

Endothelial dystrophy is diagnosed when all other causes of corneal edema have been eliminated, and the breed and age of dog are typical of the disease.

Treatment

This disease is difficult to treat because it is irreversible and progressive. There is no available treatment to restore the pumping mechanism of the endothelium. Treatment is administered to prevent progression and to treat symptoms.

A hypertonic (very concentrated) sodium chloride ointment or solution can be used to slow the rate of progression of the disease and to keep the surface of the cornea from becoming water-logged. If the surface layer can be kept healthy, then there is less chance of corneal ulcers developing.

If corneal ulcers or inflammation develop, then antibiotics may be indicated.

If the disease progresses to the point where the cornea becomes thickened and the animal is blind and painful, then certain surgical procedures may be needed to try to keep the animal comfortable.

Home Care and Prevention

It is important to follow the instructions given to you by your veterinarian. Once the sodium chloride medication is instituted, it is usually given for life. Periodic examinations are required to monitor the disease and to make adjustments in the medication. Animals that suddenly become painful (squinting, tearing) should be seen immediately by your veterinarian.