DON'T LOSE SIGHT OF GLAUCOMA

By Carrie Gustavson, University of IllinoisCollege of Veterinary Medicine

Because glaucoma in people generally progresses slowly and is caught early, many people don't realize that in animals, especially dogs, glaucoma often requires immediate emergency treatment to prevent blindness.

Why the difference? Because of the stoic nature of most animals, it is hard to know that there's anything wrong. "Dogs, especially, tolerate glaucoma very well and won't show you that they have a problem until their eye is in really bad shape," says Dr. Ralph Hamor, veterinary ophthalmology specialist at the University of Illinois Veterinary Teaching Hospital in Urbana.

Glaucoma is a frequent cause of blindness in both humans and animals. The fluid in the eye, or aqueous humor, circulates within the eye and exits through a special drain. Problems start if the drain gets plugged, causing pressure in the eye (or intraocular pressure) to build up. When that occurs, retina and optic nerve damage may result, which can compromise vision.

"In animals, glaucoma is just one of the causes of a red, cloudy, painful eye," says Dr. Hamor. "Owners should take note of those basic signs, which can point to a number of diseases."

Diagnosing glaucoma starts with a measurement of the intraocular pressure with an instrument called a tonometer. If the intraocular pressure is elevated, the dog may need emergency treatment to reduce pressure fast and prevent vision loss.

The two types of glaucoma are primary and secondary. "In secondary glaucoma, something is physically plugging the drain, so if we treat and cure the primary cause, it is possible to eliminate the glaucoma and save vision," says Dr. Hamor.

Only in secondary glaucoma do patients have a chance for a complete cure. Causes of secondary glaucoma include chronic uveitis, a tumor, and lens luxation. Cats and horses are the animals typically found to develop glaucoma secondary to another problem.

In people and dogs, primary, or hereditary, glaucoma is the form commonly found. "With dogs, certain breeds are predisposed to glaucoma," says Dr. Hamor. "These breeds ought to have their eyes evaluated yearly so that we can catch any increases in pressure and begin medical therapy." The cocker spaniel, terrier breeds, basset hound, beagle, Norwegian elkhound, and Siberian husky are especially predisposed to glaucoma.

"In a predisposed dog, it takes less pressure to cause damage than in a normal dog. That's why yearly checks are important," says Dr. Hamor. "If we can start treatment sooner, the animal may keep its vision longer."

If you notice signs of irritation, pain, discharge, or redness, in your pet's eyes, you should investigate the problem further with your veterinarian. He or she may recommend that your four-legged friend visit a veterinary ophthalmology specialist.

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Carrie Gustavson Information Specialist. The above article is reprinted as a courtesy and with permission from University of Illinois College of Veterinary Medicine - www.cvm.uiuc.edu