Glaucoma in Dogs
Dogs, like people, can develop glaucoma. Glaucoma occurs when an imbalance in production and drainage of fluid in the eye (aqueous humor) causes a buildup of fluid that increases eye pressure to unhealthy levels. The increased pressure can cause the destruction of the retina and optic disk (the spot where the optic nerve enters the eye). Open-angle glaucoma is a painless and gradual development of blind spots or loss of vision over a long period of time. Closed-angle glaucoma is a sudden increase in eye pressure with severe pain, redness, and loss of vision. Glaucoma occurs in about 1.7% of the dogs in North America. The frequency of breed-predisposed glaucoma in both eyes in purebred dogs is the highest of any animal species, except humans.
Most dogs with early to moderate longterm glaucoma are not taken to the veterinarian because the early signs—sluggish to slightly dilated pupils, mild congestion of the veins in the conjunctiva, and early enlargement of the eye—are so subtle that owners are not aware of the changes. To detect early glaucoma, a veterinarian uses an instrument called a tonometer to measure the pressure within the eye. This is often done for high-risk breeds of dogs as part of the general physical examination.
Prolonged increases of pressure within the eye can result in enlargement of the eyeball, displacement of the lens, and breaks in a membrane of the cornea. Pain usually shows itself as behavioral changes and occasional pain around the eye rather than by spasmodic winking.
There are various instruments a veterinarian can use to evaluate and manage glaucoma. The choice of medical or surgical treatment or, most frequently, a combination of both, depends on the type of glaucoma present. It is important to decrease the pressure within the eye as quickly as possible in order to minimize damage. Drugs that can draw fluid out of the eye and others that decrease production of fluid are often prescribed. After the pressure is lowered, it must be stabilized to prevent future problems. Your veterinarian will be able to suggest the appropriate medical and/or surgical treatment for your pet. Most glaucomas require longterm management.