Glaucoma in Dogs: What Is It, and What Are the Symptoms?

What Is Glaucoma in Dogs?

Glaucoma in dogs occurs when fluids within the eye don’t drain the right way.

This leads to more pressure within the eye that causes pain and discomfort for dogs. A dog’s eyes may look red and inflamed (swollen). The front part of the eye, called the cornea, can look cloudy or bluish in color, and the pupil may grow larger.

Abnormalities within the part of the eye that drains fluids can lead to glaucoma.

This can be related to genetics or due to another eye disease. Glaucoma causes damage to the retina (the part of the eye that perceives light) and the optic nerve over time.

Glaucoma in dogs is a medical emergency and should be checked by a veterinarian immediately. If left untreated, dogs may become blind.

Types of Glaucoma in Dogs

The two types of glaucoma in dogs are primary and secondary.

Primary glaucoma is due to genetic mutations that affect the part of the eye that drains fluids, while secondary glaucoma occurs because of underlying eye diseases or eye injury.

Symptoms of Glaucoma in Dogs

Common symptoms of glaucoma in dogs include:

• Swollen conjunctiva (pink part of the eye)

• Bloodshot eyes

• Bluish discoloration of cornea

• Enlarged pupils

• Bulging eyes

• Watery eye discharge

• Pawing at eye

• Squinting

• Blindness

Causes of Glaucoma in Dogs

Both types of glaucoma in dogs results from increased eye pressure:

• Primary glaucoma develops because of genetic abnormalities within the area that drains fluid from the eye. It can affect one or both eyes and typically affects middle-aged to older dogs.

  • Dog breeds that are at an increased risk for developing glaucoma include: 

    • Boston Terriers

    • Cocker Spaniels 

    • Basset Hounds

    • Siberian Huskies

    • Beagles

• Secondary glaucoma develops because of an underlying eye condition, and generally, only one eye is affected.

  • This type of glaucoma most commonly results from chronic eye inflammation (uveitis) or lens luxation. Less commonly, eye cancer may be the cause.

How Veterinarians Diagnose Glaucoma in Dogs

Pet parents should let the veterinarian know when symptoms began and if the dog is having any problems seeing, such as bumping into walls or furniture.

If a veterinarian thinks it might be glaucoma, they will do the following tests:

• Ophthalmic exam: A veterinarian does a complete eye exam to check reflexes, general appearance of the eye, and vision.

  • The retina and optic nerve will also be checked with a device called an ophthalmoscope.

• Tonometry: A veterinarian also uses a tool called a tonometer to gently tap the cornea a few times to measure eye pressure while manually holding the dog’s eyelids open.

  • A topical numbing solution is generally used. Increased eye pressure is consistent with glaucoma.

The pet parent will not need to prepare in advance for either test. A veterinary assistant will help keep the dog still and calm while the veterinarian completes these tests.

Treatment of Glaucoma in Dogs

Treatment for glaucoma in dogs is topical medication or surgery.

Topical medications that may be prescribed by a veterinarian include the following: 

• Carbonic anhydrase inhibitor: This type of medication decreases the amount of fluid made within the eye, decreasing the pressure. An example is dorzolamide. This is the preferred treatment option for glaucoma.

• Beta blocker: This medication lowers eye pressure by decreasing fluid made within the eye. An example would be timolol.

• Prostaglandin analogue: This medication lowers eye pressure by increasing the amount of fluid that drains from the eye. An example is latanoprost.

• Parasympathomimetic: This medication causes more fluid to be drained from the eye to decrease eye pressure. One example is pilocarpine.

• Hyperosmotic: These medications remove fluid from the eye quickly and are generally used in emergency settings. An example is mannitol.

Once eye pressure has been successfully lowered, the veterinarian should treat any other eye conditions that may have played a role in the glaucoma.

The veterinarian will make a long-term treatment plan in these cases.

Surgery to decrease fluid made within the eye can be done in some cases when recommended by the veterinarian. In severe cases or when blindness is present, removal of the eye (enucleation) may be recommended. 

Recovery and Management of Glaucoma in Dogs

Glaucoma in dogs is a progressive disease that must be managed but can’t be cured.

Medical management is needed for the rest of the dog’s life to control eye pressures. Even with the right treatment, the disease may progress and lead to blindness in many cases.

If glaucoma is caught early, treatment generally prevents vision loss and protects eye health.

Regular veterinary visits to check eye pressures during management are very important to make sure the medication is working and the disease is not getting worse.

The veterinarian will decide the best frequency of rechecks, based on the dog’s condition and the treatment option chosen.

Prevention of Glaucoma in Dogs

Primary glaucoma in dogs can’t be prevented since it is related to genetic abnormalities.

However, glaucoma that develops secondary to another eye condition may be preventable.

Regular veterinary visits can find eye issues early so that the right treatment can be started to prevent the development of glaucoma.

This is especially important in dog breeds that are predisposed to the condition.