Glaucoma in Dogs: Signs, Emergency Care, and Treatment

What happens inside the eye

The eye is filled with a clear fluid that is made and drained all the time. In a healthy eye, the amount made and the amount drained stay in balance. Glaucoma starts when the fluid cannot drain well. The fluid builds up and the pressure rises.

Vets describe two main forms. Primary glaucoma is inherited. The eye's drainage system does not work properly because of the dog's genes, even though the eye can look healthy for years. Secondary glaucoma is caused by another eye disease or an injury that blocks drainage. In dogs, secondary glaucoma is the more common form.

Causes and dogs at higher risk

Secondary glaucoma can follow several other eye problems.

• Inflammation inside the eye, called uveitis
• A lens that has slipped out of its normal place
• Cataracts, or eye surgery such as cataract removal
• Bleeding inside the eye
• Tumors of the eye, such as melanoma
• Injuries to the eye, including wounds that go through the surface

Primary glaucoma runs in certain breeds. They include Cocker Spaniels, Basset Hounds, Akitas, Siberian Huskies, Poodles, Boston Terriers, Great Danes, Dalmatians, and Shih Tzus. In Beagles, one inherited form has been linked to a specific gene change. Any dog, purebred or mixed, can develop secondary glaucoma after an eye injury or illness.

Signs to watch for

Sudden (acute) glaucoma usually starts in one eye, and the signs can appear within a short time. Owners often notice several of these at once.

• A red eye, with swollen, dark red blood vessels in the white of the eye
• A cloudy, hazy, or bluish look to the front of the eye
• Squinting, blinking, or holding the eye shut
• Watery tears or discharge
• A pupil that is larger than the other one or slow to react to light
• An eye that looks bigger or seems to bulge
• Rubbing the eye, or turning away when you touch the head
• Low energy or eating less
• Bumping into things or seeming unsure where things are

Glaucoma is a painful disease, and dogs do not always show pain clearly. A dog that is quiet, sleeps more, or skips meals may be hurting. A sudden rise in pressure usually causes more obvious pain than a slow one.

Slow (chronic) glaucoma is harder to spot. The pressure rises over a longer time, and sight can fade gradually with little obvious pain. Over time, high pressure can stretch the eye so that it looks larger than the other one. Some owners only notice a problem when the dog starts bumping into things.

When it is an emergency

A red, painful eye with a cloudy or bluish surface should be seen by a vet the same day. If your regular clinic is closed, it is best to call an emergency clinic. Vets treat acute glaucoma as an emergency. Blindness can happen quickly if the pressure is not lowered, and damage to the optic nerve cannot be undone.

Other conditions can look similar at first. Uveitis, corneal ulcers, and eye infections also cause a red, sore eye. An exam and a pressure check are needed to tell them apart. For that reason, it is best not to use leftover eye drops at home before the visit. On the way to the clinic, keep your dog calm and try to stop them from rubbing the eye.

How vets diagnose it

The main test measures the pressure inside the eye. Vets use a small handheld tool called a tonometer. The test is quick, and most dogs handle it well.

The vet will also look inside the eye with a light and lens to check the retina and the optic nerve. They look for a cause, such as inflammation, a moved lens, bleeding, or a tumor. Some dogs are referred to a veterinary eye specialist. The specialist may check the drainage area with a special lens placed on the eye, a test called gonioscopy, or use an ultrasound of the eye. These findings help show whether the glaucoma is primary or secondary. That matters for the outlook and for the care of the other eye.

How it is treated

The first goal is to lower the pressure as fast as possible. This protects any sight that is left and eases the pain. Vets usually start with eye drops that help fluid drain out or reduce how much fluid the eye makes. Some dogs also need other medicines given in the clinic, along with pain relief. When another disease caused the glaucoma, treating that disease is part of the plan.

After the crisis, most dogs need long-term care. That often means daily eye drops and regular pressure checks. Even if the eye looks better, please talk to your vet before stopping or changing any drops.

When drops alone cannot control the pressure, surgery may be an option. One type uses a laser to reduce how much fluid the eye makes. Another places a small drainage implant so fluid can leave the eye. These procedures are usually done by a veterinary eye specialist.

Glaucoma tends to get worse over time, even with good care, and many affected eyes lose their sight in the end. If an eye is already blind and stays painful, the vet may recommend removing it to end the pain. In some cases the inside of the eye can be replaced with an implant so the eye keeps its shape. It is a hard decision, and your vet can explain what recovery and daily life afterward will look like.

Prevention and the other eye

Inherited glaucoma cannot be prevented in a dog that is born with the risk. It often affects both eyes, one after the other. Once one eye is affected, the other eye is at high risk. Preventive drops for the healthy eye may delay the time before it is affected, so vets often recommend them along with regular pressure checks.

If you have a breed at risk, ask your vet whether pressure checks should be part of routine visits. For secondary glaucoma, early care for other eye problems is the best protection. A red eye, squinting, or a cloudy eye is worth a prompt check, even when it seems minor.

Rescued and newly adopted dogs

Glaucoma is not contagious. It does not spread to other pets or to people. If an infection caused the inflammation inside the eye, your vet can tell you whether that infection needs any extra care.

Many rescued dogs come with little known history, so past eye injuries or illnesses may not be on record. In Southern Europe, one infection to know about is leishmaniosis. It is spread by sand flies and can cause inflammation inside the eye, which is one of the causes of secondary glaucoma.

At Paw Squadron, the first stops after every rescue are the vet and a bath. Every animal gets a checkup, treatment, vaccinations, and a microchip before adoption. Glaucoma can still develop later, so it helps to watch your new dog's eyes in the first weeks and months. At the first visit with your own vet, mention any old eye injury or cloudy eye and ask whether a pressure check makes sense. If you have questions about a dog you want to adopt from us, you can send an adoption inquiry or read more guides in PawPedia.