Like people, dogs can develop glaucoma, a condition which occurs in the eye when there is an imbalance between the fluid produced and the fluid drained, a condition known as aqueous humor. This causes a buildup of fluid, which can increase the pressure within the eye to unhealthy levels. Typically this is when glaucoma develops, because the pressure often causes the complete destruction of the retina and usually the optic disk, or the spot where the optic nerve enters the eye, as well. There are two forms of glaucoma. Open-angle glaucoma is relatively painless, but will cause gradual blind spots over a period of time. Closed-angle glaucoma, on the other hand, is when a sudden increase in eye pressure occurs. This typically comes along with severe pain, loss of vision, and redness in the eye. About 1.7 percent of dogs in North America will develop glaucoma. Purebred dogs have the highest frequency of breed-predisposed glaucoma of both eyes out of all animal species, secondary to humans.
Early signs of moderate long-term glaucoma are very subtle, such as sluggish or slightly dilated pupils, early enlargement of the eye, and mild congestion of conjunctival veins. Because the signs are not readily apparent, many owners do not take their dogs to the veterinarian when signs first occur. Veterinarians usually use a tonometer, a tool that measures pressure within the eye, to detect early signs of glaucoma. For high-risk breeds this is often a part of general physical examinations and check-ups.
Enlargement of the eyeball, breaks in a membrane of the cornea, and enlargement of the eyeball itself can all occur as a result of consistent and prolonged eye pressure increases. Vigorous winking or blinking is usually not present in dogs with this type of pressure buildup. Instead, dogs typically show signs of pain through behavioral changes, and dogs may have occasional pain around the eye. Treatment depends highly on the type of glaucoma present. Medical or surgical treatment may be suggested, but typically a combination of both is used. Decreasing pressure within the eye as soon as possible is extremely critical to the minimization of damage to the eye. Usually drugs will be prescribed that either draw fluid out of the eye or decrease fluid production. Long-term management of the condition is usually required for most cases of glaucoma. The affected pet’s veterinarian will be able to prescribe the most effective treatment.