Glaucoma & a Dog's Eye Pressureby Amy S. Jorgensen
Glaucoma occurs when pressure builds up in a dog’s eyes. Dogs who suffer from glaucoma can be in significant pain because of the increased pressure; if not treated properly, the condition can lead to vision loss up to total blindness. To understand your dog’s risk, you need to understand how glaucoma occurs, which breeds are susceptible, and what symptoms to watch for.
Increased Pressure, Increased Pain
Inside your dog's eyes are cells that produce aqueous humor, a liquid that moves through the eye and out the drainage angle. When the cells and the drainage angle work correctly, the fluid helps keep the eye tissue healthy and the pressure properly balanced. When a dog has glaucoma, however, the aqueous fluid does not drain properly even though its production continues. Eventually, this increased fluid in the eye causes an increase in the intraocular pressure (IOP). According to the Animal Eye Care website, dogs can experience IOP levels of more than 50 mmHg -- normal is between 10 and 20 mmHg. The pressure is also higher than that experienced by humans with glaucoma. Human IOP levels are usually no higher than 28 mmHg.
Breeds at Risk
Canine glaucoma comes in two forms: primary and secondary. The secondary form results from an eye injury or infection, while the primary type is genetic. While any breed can acquire the secondary form of glaucoma, certain breeds are at greater risk of developing the primary type. These susceptible breeds include chows, Jack Russell terriers, basset hounds, Shar-Peis, shih tzus and beagles. All arctic breeds, such as Siberian huskies and Samoyeds, are also prone to developing primary glaucoma.
Symptoms to Spot
Unfortunately, glaucoma is not easy to spot early on. Because the IOP worsens over time, dogs may not show any visible signs of discomfort for many months or even years. The pressure may at first only cause your dog to have a headache, but eventually she may start pawing at her eye frequently. Her eye may become prone to tearing and squinting. If you begin seeing a blue haze covering the eye's clear portion -- a condition called corneal edema -- your dog needs immediate treatment for glaucoma to prevent further eye damage. Veterinarians also recommend that breeds susceptible to glaucoma should have their IOP levels tested regularly so the condition can be detected early.
Relieving the Pressure
After your dog's glaucoma is diagnosed, the veterinarian will usually attempt to reduce the IOP levels using medications. These drugs either attempt to pull the fluid from the eye or stop the production of the aqueous humor. Another treatment option is cyclodestructive surgery; it involves removing some of the cells that produce the fluid. For dogs who have chronic problems with IOP, including blindness and persistent pain, the only solution may be to surgically remove the entire eye. In many diagnoses, the glaucoma has progressed in one eye too far to save the dog's vision -- but because the condition has been identified, early steps can be taken to protect the dog's other eye.
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