Glaucoma in Dogs
Written by Small Door's medical experts
Glaucoma is an eye disease in which the pressure within the eye increases. Forty percent of dogs affected with glaucoma end up blind in the affected eye within the first year, regardless of medical treatment or surgery.
In this article:
Glaucoma is a condition that causes a build-up of fluid (referred to as aqueous fluid) and pressure in the eye. If too much fluid is made or too little fluid is drained, the pressure of the eye, called intraocular pressure (IOP), increases and causes damage to the retina and the optic nerve. This can ultimately lead to blindness.
Intraocular pressure is the fluid pressure inside the eye that is able to be maintained if the absorption or drainage and production of the aqueous humor fluid are equal. When the eye is unable to drain enough of the aqueous humor fluid it can lead to glaucoma in dogs.
Why is an increase in intraocular pressure a problem?
When intraocular pressure is high it can lead to damage or degeneration of the optic nerve and retina. This is an issue because the retina’s function is to convert images into nerve signals and the optic nerve carries these signals from the retina to the brain to produce vision. Thus, an increase in intraocular pressure will almost always result in blindness in the affected eye because of the damage to the retina or optic nerve.
Glaucoma causes pain that’s more severe in dogs than in humans. However, dogs do not show pain in the way humans can, so it may be difficult to detect when they are actually hurting. Clinical signs to look out for include:
Eye pain: Rubbing up against the floor or another object or with the paw
Redness of the eye
Cloudy cornea
Squinting
Tearing
Avoidance of light
Weak blink response
Fluttering eyelid
Pupils appear different in size
Appearance of vessels in the white of the eye
Bulging swollen eye
Vision problems: bumping into objects, difficulty finding things, walking cautiously
As a dog ages, the clinical signs may occur in one eye and then the other. Rarely will it occur simultaneously in both eyes or with equal pressure. It can also be years before the second eye becomes affected.
If you notice any signs and symptoms of glaucoma, have your dog checked out immediately. Time is of the essence when it comes to this condition. Not only is it painful, it will lead to irreversible blindness if left untreated.
In primary glaucoma, the fluid flow rate into or out of the eye is abnormal, which increases pressure. It is usually inherited because of a genetic predisposition within certain breeds. It is not the result of an underlying disease as is the case in secondary glaucoma. The condition can happen at any age, but most dogs with primary glaucoma are diagnosed early or mid-life, around 3-7 years old.
Secondary glaucoma is the result of another or concurrent eye condition. Bleeding, swelling, and inflammation can occur, scar tissue may form, and the drainage of fluid is hindered, if not blocked entirely. Secondary glaucoma is more common than primary glaucoma in dogs. Triggers can include:
Tumors
Infections
Advanced cataracts
Eye cancer
Inflammation
Chronic retinal detachment
Whether your dog is diagnosed with primary or secondary glaucoma, the result is the same: the inability to drain fluid properly and keep the pressure in the eye at a safe level. In turn, the eye cannot remain healthy, and vision is lost.
Your veterinarian will first determine the type of glaucoma your dog has before creating a course of action. If your dog is diagnosed with secondary glaucoma, the original condition that caused glaucoma must be treated promptly.
For instance, in dogs with cataracts that can be removed surgically, treatment can be effective at putting a stop to the progression of glaucoma symptoms, and pressure within the eye can be relieved with medication or laser treatment. If your dog has been in an accident that caused significant damage to the eye structure, the best solution may be the complete removal of the eye to reduce the pain and prevent glaucoma from becoming an ongoing issue.
Time is a critical factor for treating glaucoma, which is why it’s vital that a dog showing signs sees a veterinarian immediately. Along with gathering as much medical history as possible, the veterinarian will conduct an ophthalmologic exam. In some cases, your veterinarian may refer you to an ophthalmologist for a more detailed examination of both eyes.
The veterinarian will test the intraocular pressure (IOP) using a tonometer, a tool for checking the pressure exerted by the fluid inside the eye. There are a few types of tonometers — those that touch the eyeball directly, one that only touches the eyelid, and another that doesn’t touch the eye at all.
One type of tonometer blows a puff of air onto the eye to measure the indentation. Another type presses a small plastic disk against the eyeball to measure pressure. A drop of anesthetic is often applied first to keep the dog comfortable during the exam.
In the event of an eye abscess, injury, or tumor, an X-ray or ultrasound may be done to get a closer look at the space around the eye.
With sudden glaucoma, the pupil has a sluggish response to light, the blink response is weak or nonexistent, the cornea is swollen or cloudy, the eye is red, inflamed, tearing, and the dog may be squinting.
In chronic glaucoma, the pupil has no response to light, and the blink response is absent. The cornea is cloudy, the eye is red and inflamed, and often enlarged. Tearing is possible, and vessels are seen on the cornea.
Treatment is dependent on the severity of glaucoma, including any underlying diseases that may be responsible for the presence of the condition in the first place. Those must be addressed and taken care of to prevent the condition from reappearing. Treatment options include:
Medication: These are given to lower the pressure within the eye and get it back to the normal range as fast as possible with the goal of preserving the dog’s vision. Most medications are topical or ointments and may need to be administered up to three times a day. There are also oral medications that can control the pain and discomfort that accompanies the condition. In some severe cases, your veterinarian may recommend hospitalizing your dog so that injectable medications (such as mannitol) can be used to lower IOP more quickly.
Cyclocryotherapy: Cold temperatures are used to kill the cells that produce intraocular fluid. The fluid may be drained and the fluid producing cells altered to stop fluid buildup within the eye. With early detection, this procedure can slow down or stop glaucoma from progressing further.
Surgery: Unfortunately, in most long-term cases, the eye will need to be removed. The longer glaucoma goes undetected, the more of a chance that the optical nerve will be damaged beyond repair, which means surgery and possible removal of the eye. When removing the eye, the empty socket can be closed up or the eye cavity filled with an orb to keep the ocular space filled.
Is there a cure for glaucoma in dogs?
There is no cure for glaucoma, but there are ways to treat it and in some cases manage the condition. When it comes to secondary glaucoma, there is the possibility for a cure, and in turn one less potential contributor to glaucoma.
Glaucoma can affect all dogs, although certain breeds have a genetic predisposition for developing the condition within their lifetime, including:
Cocker Spaniel
Chow Chow
Samoyed
Poodle
Beagle
Jack Russell Terrier
Siberian Husky
Dalmatian
Chihuahua
Basset Hounds
Great Dane
Is glaucoma in dogs contagious for humans or other pets?
Glaucoma is not contagious between animals or even between humans. It is hereditary in certain breeds, however.
What is the cost of treating glaucoma in dogs?
The cost to treat glaucoma varies with the route in which your veterinarian recommends. Managing glaucoma can be expensive: With medications, routine checkups (specialists, like an ophthalmologist, usually tend to run higher in cost), the costs can add up to thousands of dollars throughout the dog’s life. If surgery is necessary, while the initial cost may be high, it’s a cost that is usually not repeated. Not all veterinarians charge the same amount, and geographic location can play a role when it comes to the cost of treating your dog’s glaucoma.
Since treatment can get expensive, pet insurance may be an option. If you don’t already have a plan, inquire about whether a new plan would cover your dog’s condition after an initial grace period.
When deciding on the best course of treatment, there are several factors to consider. Cost, cosmetic preference (when removing the eye is necessary), vision potential, and the type of glaucoma your dog has all add up. Because there are no guarantees, it’s best to weigh the costs with the potential gains and see what makes the most sense for your dog.
If the eye needs to be removed as the result of vision loss because of glaucoma, your dog will need to wear an Elizabethan collar/cone for protection until the sutures are removed.
The lingering effects of the anesthesia and the possibility of discomfort may be present in the first few days after surgery but can be managed with medication. A checkup is required a few days afterward, but the sutures won’t be removed until after 10-14 days. Complications are rare but still possible, although the majority of dogs who have the surgery make a full recovery.
If glaucoma is detected early, treatments will be monitored, so follow-up appointments will be part of your dog’s management plan. For breeds predisposed to developing glaucoma, checkups twice a year help in early detection.
Regardless of whether management consists of medication and monitoring, or taking things a step further with surgery, the result is the same — to bring your dog relief.
Secondary glaucoma can be prevented by keeping your dog safe, doing your best to avoid injuries and accidents, staying on top of health issues and seeking out treatment for any infection, especially eye related, as soon as possible.
Primary glaucoma, however, is not preventable because it is the result of genetics. But steps can be taken beforehand to try to slow any degenerative changes to your dog’s eyes and reduce their chances of developing glaucoma.
Antioxidants like beta-carotene, vitamins E and C, as well as nutraceuticals can all be taken to reduce the amount of damage that occurs to the cells of the eye.
Reducing stressors in your pet’s environment can help manage the oxidative damage that occurs throughout the body, including the eyes.
Eliminating pressure to your dog’s neck is also critical because we don’t want to increase inter-cerebral or intraocular pressure through any type of tight collar or harness system.
For aging pets and higher risk breeds, make sure your veterinarian check your dog’s eye pressure during wellness exams.
Regardless of the type of glaucoma your dog has, early detection is the best way to prevent the progression of the condition and the resulting blindness that is most often associated with glaucoma. Identifying those subtle pressure changes in the eye and addressing medically early on, is the best way to prevent further damage.
Is there a vaccine for glaucoma in dogs?
There isn’t a vaccine that treats or prevents the onset of glaucoma.
Glaucoma is a very painful condition that causes a build-up of fluid and pressure in the eye. The pressure causes damage to the eye, and can eventually cause blindness and require removal of the eye. Dog owners should be vigilant for any signs of eye pain, or changes to the look of the eyes, and take their dog for evaluation immediately.
