GLAUCOMA IN DOGS

Increased intraocular pressure in the dog’s eye due to the inability of the eye to drain excess fluids results in serious ocular disease known as glaucoma. Inability of the eye to drain excess fluids causes intraocular pressure increase which then puts pressure on the retina and optic nerve, causing them to become damaged.

Damage to the optic nerve occurs because this nerve transmits all of the visual information from the retina to the brain, and if damaged, it will result in either total blindness or at least some degree of blindness. A sudden onset of glaucoma is referred to as acute, whereas a gradual development is chronic.

Chronic glaucoma may be less immediately severe than acute glaucoma; however, both forms have potential for permanent vision loss. Due to its irreversible nature and rapid progression, glaucoma is viewed as an emergency medical condition by veterinarians.

Causes

Glaucoma happens because there has been an imbalance in the rate at which the eye produces fluids versus the rate at which these fluids drain from the eye. Fluid buildup within the eye may occur either due to a normal developmental issue (abnormality) of the drainage system in the eye itself or due to an existing disease affecting the eye.

Primary (Inherited) Glaucoma

The most common type of glaucoma is called primary glaucoma; it occurs when no other underlying eye condition exists and is typically inherited. Primary glaucoma is due to a developmental abnormality of the drainage angle in the eye, causing an inability to properly drain fluid.

Dog breeds more commonly affected with this hereditary disorder include:

• Cocker Spaniels
• Basset Hounds
• Beagles
• Shih Tzus
• Siberian Huskies

These breeds have a genetic predisposition to developing primary glaucoma, which often occurs during adulthood or middle age.

Secondary Glaucoma

Secondary glaucoma occurs due to a pre-existing eye condition or accident that obstructs the drainage of fluids through the eye. Some examples of conditions leading to secondary glaucoma include:

• Uveitis
• Cataracts (advanced stage cataract)
• Lens Luxation (lens displacement)
• Eye injuries or accidents
• Tumor formation in the eye

Chronic eye infections or damage

Symptoms

Glaucoma’s signs will depend upon if you have acute glaucoma or chronic glaucoma; however, both forms are usually very painful and noticeable.

The most common signs for each form of glaucoma include:

• Redness of the eye
• The cornea appears cloudy or bluish
• Excessive tearing or eye discharge
• Squints to keep the eye shut
• Pupil becomes dilated and does not react as normal when exposed to light
• Eye becomes bulging or swollen
• Vision loss or impaired vision
• Behavioral changes associated with eye pain, such as irritability or restlessness
• Rubbing or pawing at the eye

Symptoms of Acute Glaucoma may come on fast and become extremely uncomfortable over a period of hours.

Risks

One of the most serious eye diseases in dogs is the quick and irreversible effects of glaucoma.

Permanent Vision Loss

The high pressure in your dog’s eye will cause damage to the optic nerve. Increased intraocular pressure can rapidly and permanently damage the optic nerve, leading to irreversible vision loss if not treated promptly.

Severe Eye Pain

Your dog with glaucoma is very uncomfortable and is experiencing extreme eye pain. There is a constant headache-like sensation that your dog will experience. Dogs may become withdrawn, restless, or irritable because of the significant pain associated with glaucoma.

Structural Eye Damage

Increased pressure for an extended period of time on your dog’s eyes can cause stretching and destruction to the shape of your dog’s eyes. This can cause buphthalmos (enlargement of your dog’s eye) and corneal degeneration.

Loss of the Eye

If your dog has suffered enough pain and pressure in either the early stages or the later stages of glaucoma that the condition cannot be managed, surgery to remove the eye may be performed to maintain the quality of your dog’s life.

Diagnosis

The sooner that you diagnose your pet’s glaucoma, the better chance they have of maintaining their vision and controlling pain.

Tonometry (Eye Pressure Measurement)

A tonometer can be used by a veterinarian or technician to determine whether there has been an increase in intraocular pressure. Intraocular pressure is increased in cases of glaucoma.

Eye Examination

A complete ophthalmic examination helps assess the cornea, lens, iris, retina and other structures that may be affected by glaucoma.

Additional Diagnostic Tests

The veterinarian may also perform other diagnostic testing depending upon what is happening with your pet, such as:

• Performing gonioscopy to see the structure of the drainage angle
• Using ultrasound to look at damage internally
• Performing fluorescein staining to detect injury to the cornea
• Conducting general health testing to find secondary glaucoma

Treatment

Treatment focuses on lowering intraocular pressure, relieving pain, and preserving vision whenever possible.

Medical Management

The first treatments will probably be oral and/or topical, with options including:

• Treatment by eye drops that help reduce the production of fluids within the eye and promote a better flow through the trabecular meshwork
• Oral medications to lower the IOP
• Anti-inflammatory medications to control swelling and pain
• Medications to provide pain relief

In acute glaucoma situations, immediate treatment is necessary so you can have an increased chance of retaining your remaining vision.

Surgical Treatment

If medical therapy is insufficient or vision cannot be preserved, then surgical therapy should be considered. Your surgeon has several options

• A laser procedure to stop the production of additional aqueous humor
• Surgical implants designed to enhance the outflow of aqueous humor from the eye
• Removal of the affected eye (enucleation) may be recommended for eyes that are permanently blind and painful.

Even when vision cannot be saved, medical and surgical treatments can help relieve pain and maintain a good quality of life.

Prevention

Not all types of Glaucoma are preventable. Inherited types of Glaucoma cannot be prevented. However, early detection and ongoing monitoring may help reduce the risk of severe complications and vision loss.

Regular Eye Examinations

By having your pet’s eyes checked by a veterinarian on a routine basis, you will be able to recognize any changes in their eye that could lead to long-term vision loss.

Breed Awareness

Owners of breeds predisposed to glaucoma should monitor their dogs closely for signs of eye disease and seek veterinary attention promptly if abnormalities develop.

Early Treatment of Eye Diseases

Any eye condition, including but not limited to uveitis, cataract, or injury, needs to be addressed quickly so that secondary Glaucoma does not develop.

Monitoring for Early Signs

Redness, Cloudy eyes, squinting, or other behavior that indicates possible eye pain; all need to be taken seriously.