Glaucoma in dogs is a build-up of fluid pressure inside the eye that damages the retina and optic nerve. It is painful, it can cause permanent blindness, and a sudden red, cloudy or swollen-looking eye with a wide pupil is an emergency: call your vet or your nearest 24-hour emergency clinic the same day. Slow, "open-angle" forms are quieter and easier to miss, so knowing the early signs matters for dog owners from Perth to Sydney.
What is glaucoma in dogs?
The eye constantly makes a clear fluid (aqueous humour) and drains it through a narrow angle at the edge of the iris. Glaucoma happens when production and drainage fall out of balance, so pressure climbs high enough to injure the retina and optic nerve. The Merck Veterinary Manual describes a slow, often painless loss of vision (open-angle) and a sudden pressure spike with severe pain, red eyes and vision loss (closed-angle).
Glaucoma is either primary (an inherited drainage problem, common in purebreds) or secondary (pressure raised by another problem such as uveitis, a displaced lens or a tumour).
Signs of glaucoma in dogs
- Early: a slightly enlarged or sluggish pupil, faint redness or engorged veins on the white of the eye, mild eye enlargement, or "off" behaviour such as hiding.
- Advanced: a bluish or cloudy cornea, a firm or bulging eyeball, a dilated pupil that barely reacts to light, obvious redness, bumping into furniture.
- Pain: usually shows as lethargy, appetite loss or pawing at the face rather than constant squinting.
Compare with our guides to why dogs' eyes are red and dog cloudy eye. In Australia, grass seeds and bush dust can also irritate the eye, so a red, squinting eye after a bushwalk should be checked rather than assumed to be glaucoma or an irritation. If one eye looks different from the other, do not wait to see whether it passes.
Which dogs are most at risk?
A large North American hospital-database study (Gelatt and MacKay, 2004) found breed-related glaucoma prevalence rose from 0.29% in 1964–1973 to 0.89% in 1994–2002. The highest rates in the latest period were in the American Cocker Spaniel (5.52%), Basset Hound (5.44%), Chow Chow (4.70%) and Shar-Pei (4.40%). Most breeds were first diagnosed between 4 and 10 years of age. A variant in the ADAMTS10 gene is considered the likely cause of open-angle glaucoma in Beagles (Kuchtey et al., 2013). Ask your vet whether eye-pressure checks (tonometry) make sense for your breed.
Types at a glance
| Type | Onset | What owners notice | Urgency |
|---|---|---|---|
| Closed-angle (primary) | Sudden | Red, painful, cloudy eye; wide pupil; vision loss | Emergency: same day |
| Open-angle (primary) | Gradual | Subtle pupil change, slow vision loss | Book a vet exam promptly |
| Secondary | Varies | Signs of the underlying problem plus pressure signs | Same-day to urgent |
Diagnosis and treatment in Australia
Vets measure intraocular pressure with a tonometer and examine the pupil, cornea and drainage angle. Many general practices refer to a specialist veterinary ophthalmologist (ANZCVS members), usually based in the larger cities, so ask early about travel and referral costs. Treatment aims to lower pressure quickly and then keep it stable: per Merck, medication that draws fluid out or reduces its production, often with surgery or long-term drops. A blind, enlarged, painful eye may be removed for comfort. Check what your pet insurance covers for ongoing eye conditions. See also dog cataract surgery cost and uveitis in dogs.
What about the other eye?
A multicentre study of 117 dogs with primary angle-closure glaucoma in one eye found 70.9% developed glaucoma in the second eye within 5 years (median 2.15 years), and no prophylactic drop regimen tested was clearly better than another (Donohue et al., 2026). Keep your recheck appointments.
What not to do at home
- Do not wait overnight when the eye is red, cloudy or painful.
- Do not use human redness-relief drops or another pet's leftover medication.
- Do not press or massage the eye.
A squinting dog is equally urgent: see dog squinting one eye and dog eye ulcer.
Daily eye hygiene alongside veterinary care
Once your vet has started treatment, gentle hygiene keeps lids and fur clean. Pure Majesty Pets Dog Eye Drops are ophthalmic-grade, sterile-filtered (10 micron), pH 7.0–7.2 to match natural tears, with sodium hyaluronate 0.05%, chamomile 2%, aloe vera 8% and sodium phytate 0.15%; plain saline contains none of those. They are non-medicated hygiene drops: they do not lower eye pressure or treat glaucoma and never replace prescribed medication. Check with your vet first. Free shipping worldwide. Read our pillar guide on dog eye infection warning signs or visit the Pure Majesty Pets homepage.
Frequently asked questions
Is glaucoma in dogs painful?
Yes, especially when pressure rises quickly; pain often shows as lethargy, hiding or rubbing the face.
Can a dog go blind from glaucoma?
Yes. High pressure damages the retina and optic nerve, and the damage can be permanent.
Will the other eye be affected?
In primary angle-closure glaucoma, 70.9% of dogs in one study developed it in the second eye within 5 years.
Scientific References
- Gelatt KN, MacKay EO. Vet Ophthalmol. 2004;7(2):97-111. PMID 14982589.
- Kuchtey J, et al. Invest Ophthalmol Vis Sci. 2013;54(3):1881-6. PMID 23422823.
- Donohue LK, et al. Vet Ophthalmol. 2026;29(1):e70038. PMID 40485308.
- Merck Veterinary Manual. Glaucoma in Dogs.
This article is for informational purposes and is not veterinary advice. A red, cloudy, painful or enlarged eye is an emergency: contact your vet or nearest emergency clinic immediately. Talk to your vet before starting any product, especially if your dog is pregnant, nursing, on medication, or has a diagnosed condition.