Glaucoma in Dogs: Signs, Treatment & Emergency Care
- See your vet immediately if your dog has a suddenly red, cloudy, painful eye. Glaucoma can damage vision within hours, and eye pressures above about 40-50 mmHg need emergency treatment.
- Common signs include a bloodshot eye, blue-gray corneal haze, a dilated pupil, squinting, tearing, head shyness, and sudden vision loss or bumping into things.
- Treatment options may include pressure-lowering eye drops, oral medication, referral to a veterinary ophthalmologist for laser or shunt surgery, or pain-relief surgery if the eye is blind.
- When one eye has primary glaucoma, the other eye is often at risk too, so your vet may discuss preventive drops and monitoring for the second eye.
What Is Glaucoma?
Glaucoma is a painful eye condition caused by abnormally high pressure inside the eye, called intraocular pressure or IOP. The eye is always making and draining fluid. When that drainage slows or becomes blocked, pressure rises and can injure the retina and optic nerve.
In dogs, normal IOP is usually around 10-25 mmHg. Once pressure climbs well above that range, damage can happen quickly. Cornell notes that pressures above 40-50 mmHg require emergency treatment, which is why a red, cloudy eye should never wait until the next routine visit.
Glaucoma may be primary, meaning the drainage angle is inherited and abnormal, or secondary, meaning another eye problem caused the pressure increase. Secondary glaucoma can develop with uveitis, lens luxation, bleeding inside the eye, tumors, or trauma. Both forms are serious, but the treatment plan depends on the cause, whether vision is still present, and how painful the eye is.
Signs Your Dog May Have Glaucoma
- Sudden red or bloodshot eye — high concern, especially if it appears over hours
- Cloudy, blue, or hazy cornea — common with acute pressure spikes
- Dilated pupil that responds poorly to light — urgent finding
- Squinting, blinking, or holding the eye closed — suggests pain
- Tearing or watery discharge — often early but nonspecific
- Pawing at the face, head shyness, or reluctance to be touched — pain-related signs
- Lethargy, hiding, reduced appetite, or seeming "off" — pain can affect the whole dog
- Vision changes such as bumping into furniture or missing steps — emergency if sudden
- Eye looks larger or bulging — often a more chronic sign and vision may already be lost
A suddenly painful eye is always urgent. See your vet immediately if your dog has redness, cloudiness, a large pupil, or sudden vision changes. Chronic glaucoma can cause the eye to enlarge over time, but acute glaucoma is the bigger emergency because vision may be lost very quickly. Even if you are not sure it is glaucoma, the same signs can happen with other serious eye problems that also need same-day care.
What Causes Glaucoma?
Primary glaucoma happens when the eye's drainage angle does not form normally. This inherited problem is often linked to goniodysgenesis, a structural abnormality that makes fluid drainage less efficient. It usually shows up first in one eye, but the second eye is commonly affected later.
Breeds often reported as higher risk include Cocker Spaniels, Basset Hounds, Beagles, Siberian Huskies, Chow Chows, Shar-Peis, and Shiba Inus. Risk varies by line and individual dog, so breed alone does not confirm disease.
Secondary glaucoma develops because another eye condition blocks drainage or changes fluid flow. Common triggers include uveitis, lens luxation, bleeding inside the eye, intraocular tumors, and trauma. In practice, secondary glaucoma is common and can affect any breed.
Finding the cause matters. A dog with primary glaucoma may need preventive treatment in the other eye, while a dog with secondary glaucoma needs treatment directed at the underlying eye disease as well as the pressure.
How Is Glaucoma Diagnosed?
Diagnosis starts with a full eye exam and tonometry, which measures intraocular pressure. Your vet may use a handheld device such as a Tono-Pen or rebound tonometer. Pressure is only one piece of the picture, though. Your vet also looks at the cornea, pupil, lens position, retina, and optic nerve, and checks whether the eye still appears visual.
Additional testing may include gonioscopy to evaluate the drainage angle, especially if primary glaucoma is suspected. This can help estimate risk to the other eye. If the inside of the eye cannot be seen because of cloudiness or bleeding, ocular ultrasound may help identify lens luxation, retinal detachment, or a mass.
In referral settings, a veterinary ophthalmologist may also use advanced imaging or retinal testing when surgery is being considered. These tests help answer practical questions: Is this primary or secondary glaucoma? Is vision still salvageable? Which treatment tier best matches this dog and family?
Treatment Options for Glaucoma
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Medical Management and Emergency Pressure Control
- Same-day exam and tonometry
- Pressure-lowering eye drops such as latanoprost and/or dorzolamide-timolol
- Possible oral carbonic anhydrase inhibitor such as methazolamide
- Pain control and anti-inflammatory treatment when appropriate
- Frequent rechecks for repeat pressure checks
- Discussion of preventive drops for the other eye if primary glaucoma is suspected
Specialist Vision-Sparing Procedures
- Veterinary ophthalmology consultation
- Advanced diagnostics to confirm cause and visual potential
- Cyclophotocoagulation or similar laser procedure to reduce fluid production
- Possible gonioimplant or drainage shunt in selected cases
- Post-procedure medications and scheduled pressure rechecks
Pain-Relief Surgery for Blind or Refractory Eyes
- Enucleation for a blind, painful eye
- Optional intrascleral prosthesis in selected cases
- Histopathology if a tumor or other hidden disease is a concern
- Hospitalization, anesthesia, pain medication, and recheck care
- Referral-level management for complex or bilateral disease
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Glaucoma
Bring these questions to your vet appointment to get the most out of your visit.
- Do you think this is primary glaucoma or secondary glaucoma from another eye problem?
- Is there still vision in this eye, and how does that change our treatment options today?
- What is my dog's eye pressure right now, and what pressure range are you aiming for?
- Should we start preventive treatment or monitoring for the other eye?
- Which medications are for pressure control, which are for pain, and how often do they need to be given?
- When would you recommend referral to a veterinary ophthalmologist?
- If this eye is already blind, what options are available to keep my dog comfortable?
- What recheck schedule do you recommend over the next few days and weeks?
How to Prevent Glaucoma
Primary glaucoma cannot usually be prevented outright, but earlier detection can make a real difference. If your dog is in a higher-risk breed, ask your vet whether baseline eye exams, tonometry, or referral screening of the drainage angle make sense.
If one eye develops primary glaucoma, the second eye is often at risk. Preventive treatment for the unaffected eye may delay a future pressure spike, and regular monitoring helps catch changes before severe pain or blindness develops.
Secondary glaucoma prevention focuses on the problems that trigger it. Prompt care for uveitis, lens luxation, eye trauma, or bleeding inside the eye may reduce the chance of a pressure crisis. The most practical prevention step for most families is knowing the warning signs and treating a red, cloudy, painful eye as an emergency.