Glaucoma in Dogs: Causes, Symptoms and Treatment Options

Your dog’s eyes are windows to their soul and it can be upsetting when an eye disease threatens their comfort or vision. Glaucoma, which is a buildup of pressure inside the eye, can cause discomfort and, ultimately, vision loss.

Understanding what glaucoma is, what to look for and ways to manage it can help you and your pup adjust to life with the condition.

What Is Dog Glaucoma?

Glaucoma is a condition caused by high pressure inside the eye, or elevated intraocular pressure (IOP). Your dog’s eye continuously produces a fluid called aqueous humor, which helps to maintain its shape, similar to air in a beach ball.

To prevent eye pressure from rising too high, aqueous humor must drain from the eye at the same rate that new fluid is produced. When something disrupts this drainage process, fluid builds up, pressure increases and delicate structures inside the eye can become damaged.

Glaucoma is classified as primary or secondary, depending on whether it occurs on its own or develops as a result of an underlying condition.

Primary glaucoma

Primary glaucoma is a genetic condition that occurs more often in certain breeds, including:¹

• Basset hounds
• Beagles
• Chow chows
• Cocker spaniels
• Poodles
• Terriers

Dogs with primary glaucoma are born with a defect in the eye’s drainage system, which allows fluid and pressure to build. Signs typically begin during early adulthood or middle age. The condition often starts in one eye and then progresses to the other eye months or years later.

Secondary glaucoma

This type of glaucoma develops when the eye’s drainage system is affected by another eye disorder. Inflammation is a common cause, as inflammatory cells can block or damage the drainage ducts. Secondary glaucoma can occur in any dog, regardless of their genetic makeup and may involve one or both eyes.

Your vet may also classify glaucoma based on how long symptoms have likely been present. Acute glaucoma appears quickly, while chronic glaucoma may go on for a long time before a dog shows signs.

Common Causes of Glaucoma in Dogs

Primary glaucoma in dogs is genetic. Affected breeds are born with narrow or closed drainage ducts, a condition called goniodysgenesis.

Secondary glaucoma results from another eye condition that blocks or impedes fluid drainage. Causes include:

• Cataracts. Cataracts can leak protein into the eye, causing an inflammatory reaction and secondary glaucoma.
• Eye trauma. Injury to the eye can trigger swelling, bleeding or inflammation that disrupts fluid balance.
• Eye tumors. A mass inside the eye can obstruct normal fluid circulation.
• Lens luxation. When the eye’s lens slips out of place, it can physically block fluid flow.
• Uveitis. Uveitis is an inflammatory condition that can lead to scarring and blockage of drainage pathways.

Symptoms of Glaucoma in Dogs

Glaucoma can be difficult to detect in its early stages and can mimic the appearance of many other eye conditions. The signs are often subtle, especially in slow-onset primary glaucoma. In cases of secondary glaucoma, pet owners may notice signs of the primary problem before signs of glaucoma.

Common signs of glaucoma in dogs include:

• Bulging eye
• Cloudiness or bluish discoloration of the eyes
• Decreased appetite or activity
• Large pupil
• Redness
• Vision loss

Symptoms can build gradually or appear suddenly. Although glaucoma is painful, you may not know your pet has it until the affected eye loses vision. Many dogs adjust to the chronic discomfort and may not show signs of pain, especially if the pressure increase develops slowly.

Diagnosing Your Dog’s Glaucoma

To diagnose glaucoma, your veterinarian will perform a thorough eye exam and review your dog’s history. They will also measure your dog’s IOP using a special instrument called a tonometer. A diagnosis of glaucoma is based on an abnormally high eye pressure and visible changes to the optic nerve in the back of the eye.

After administering numbing eye drops, your vet will gently touch the surface of your dog’s eye with the instrument to get a reading. A normal IOP reading is around 10 to 20 mmHg. Pressure readings above 25 mmHg may indicate glaucoma and readings above 35 mmHg cause pain.

If your primary veterinarian or an emergency vet suspects glaucoma, they may start treatment and refer you to a veterinary ophthalmologist for additional testing and long-term management.

Additional tests can reveal the cause of secondary glaucoma or determine whether the unaffected eye is also at risk of primary glaucoma. These include:

• Blood panels. General organ function tests, blood work and infectious disease screening can help identify the root cause of uveitis, a common trigger for secondary glaucoma.
• Gonioscopy. This test uses a special lens and a handheld microscope (slit lamp) to evaluate the eye’s drainage angle.
• Fungal tests. Systemic fungal diseases (e.g., blastomycosis, Valley fever) can cause eye inflammation and glaucoma in addition to being life-threatening. Ruling out these infections is important if your dog’s symptoms are concerning and you live in an endemic area.
• Ocular ultrasound. A specialized ultrasound machine can check for tumors, lens displacement or retinal detachment if the eye is too cloudy to examine.

Treating Glaucoma in Dogs

The goals of glaucoma treatment are to reduce pressure, manage pain and preserve vision for as long as possible. Treatment may include medical or surgical options. 

Medical management

Glaucoma management usually includes eyedrops to reduce intraocular pressure and associated inflammation. Some dogs need multiple medications several times a day to keep eye pressure under control.

Medical treatments for glaucoma may eventually stop working, as glaucoma tends to progress over time. When this happens, your veterinarian may recommend adding new medications or considering a surgical procedure.

Regular visits and pressure checks are critical to the success of glaucoma treatment. Pressure can change without your noticing and permanent vision loss may develop if the pressure remains high for too long.

Emergency treatment

If your dog’s eye pressure is very high at the time of diagnosis or they develop a pressure spike during the course of treatment, your vet may recommend treatments to bring the pressure down quickly before discussing a long-term plan. These may include:

• Aqueocentesis. This involves inserting a small needle into the front part of the eye to drain fluid and temporarily relieve excess pressure.
• Hospitalization. Your vet may recommend a short stay for multiple rounds of eyedrops and eye pressure monitoring.
• Mannitol. This medication may be given via IV infusion to quickly lower eye pressure.

Surgery

If medical treatments stop working or the medication schedule becomes unmanageable, a veterinary ophthalmologist may recommend surgery. There are two broad categories of glaucoma procedures: vision-sparing and comfort-promoting.

A vision-sparing surgery is for dogs who still have vision in the affected eye(s). Options may include laser surgery (i.e., endocyclophotocoagulation) to destroy the fluid-producing cells in the eye, or shunt surgery to open the drainage angle. These procedures have variable success rates and require careful consideration.

Comfort-promoting procedures are for dogs who have lost vision in one or both eyes to glaucoma. Once vision is gone, it cannot be restored, but blind dogs can live a full, happy, high-quality life after an adjustment period. Eye removal surgery or ciliary body ablation — an injection of medication into the eye — can help to eliminate any pain your dog may be experiencing.

How Much Does It Cost to Treat a Dog’s Glaucoma?

Treatment for glaucoma includes frequent eye exams, pressure monitoring and prescription medications. The table below shows average* costs associated with eye care in dogs:²

The cost of glaucoma surgery varies depending on the specific procedure and where it’s performed. A specialist must perform vision-sparing glaucoma procedures, while most general practice veterinarians can perform eye removal surgery.

The national average cost* for cataract surgery in dogs is $3,481 per eye, but the cost can range from $2,758 to $6,336.² Although cataract surgery is not the same as glaucoma surgery, it requires a similar approach, equipment, expertise and surgical time, so it’s reasonable to assume that the cost for glaucoma surgery would be similar.

Eye removal surgery (i.e., enucleation) at a nonprofit clinic could cost $897 for one eye or $1,348 for both eyes.³

Glaucoma Prevention in Dogs

Glaucoma is difficult to prevent, but the right treatment plan can help slow progression. Routine eye exams and periodic eye pressure tests can screen for glaucoma in high-risk breeds, so the condition can be caught early. You can also visit a veterinary ophthalmologist to determine whether your dog has any underlying eye conditions that could lead to secondary glaucoma.

Primary glaucoma sometimes goes undiagnosed until after a dog loses vision in the first affected eye. In these cases, the goal is to delay the development of glaucoma in the other eye by starting anti-glaucoma eye drops. While this treatment won’t prevent glaucoma from developing, it can help slow the rise in pressure, making it easier to identify and treat glaucoma in the earliest stages.

To help prevent secondary glaucoma, follow your veterinarian’s recommended treatment plan for any eye conditions your dog may have, such as uveitis, cataracts or a lens problem.

Living With Glaucoma in Dogs

Glaucoma can be a devastating diagnosis for pet parents, but the good news is that even if your dog loses vision over time, they can continue to live a happy, full life with your support and treatments to keep them comfortable. Understanding the disease and working closely with your veterinary team to set up a treatment plan can help you provide the best possible care for your pup.

Frequently Asked Questions About Glaucoma in Dogs

If you’re still wondering how glaucoma could affect your dog, here are answers to questions pet owners commonly ask.

CareCredit Credit Card Financing for Dogs

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Author Bio

Angela Beal, D.V.M., has more than 20 years of experience as a veterinarian. Leveraging her background in private practice and academia, she uses her passion for writing to convey information to pet owners to help them keep their pets healthy and happy.