Quick answer: Glaucoma is high pressure inside the eye, and in dogs it is an emergency. A red eye with a bluish, steamy cornea, a wide fixed pupil, squinting, pain and sudden vision loss on that side means a vet today, because the optic nerve can be permanently damaged within 24 to 72 hours. Primary glaucoma is inherited and hits certain breeds; secondary glaucoma follows uveitis, a slipped lens, a mature cataract or a tumour and can affect any dog. Treatment starts with pressure-lowering drops and sometimes surgery, and the moment one eye is diagnosed, the other eye needs preventive drops and regular pressure checks.
Signs that mean go now
- A red, bloodshot eye, often with a bluish or grey haze over the whole cornea
- A pupil that stays large and does not shrink in bright light
- Squinting, holding the eye shut, pawing or rubbing, head-shyness
- Lethargy, hiding, going off food, a dog who seems suddenly old, all from pain
- Bumping into things on one side, not tracking on that side
- An eye that looks larger or bulges compared with the other, within days
Glaucoma pain is a deep headache-type pain that dogs rarely show by crying. They go quiet. If your dog has any two of the signs above, do not wait for morning.
What is happening inside the eye
The eye constantly makes fluid (aqueous humour) and drains it through an angle where the iris meets the cornea. When drainage fails, fluid backs up, pressure climbs from a normal 10 to 20 mmHg to 30, 40, 60 or more, and the pressure crushes the optic nerve and the retinal cells feeding it. The cornea clouds because fluid is forced into it. Nerve damage becomes permanent within a day or two at high pressures.
Primary vs secondary glaucoma
Primary glaucoma is an inherited narrowing or malformation of the drainage angle. It shows up in middle-aged to older dogs and runs in Cocker Spaniels, Basset Hounds, Beagles, Chow Chows, Shar-Peis, Siberian Huskies, Samoyeds, Boston Terriers, Bouviers des Flandres, Norwegian Elkhounds and others. It almost always affects both eyes eventually, one first. Secondary glaucoma happens when something blocks the drain: inflammation inside the eye (uveitis), a lens that has slipped out of place (common in terriers), a mature cataract leaking protein, bleeding, or a tumour. Any breed, any age. Treating the cause early is the whole game, which is why a maturing cataract needs regular pressure checks and why a red eye in a diabetic dog is urgent (see diabetic dog cataracts).
What the vet will do
- Measure the pressure with a tonometer, in both eyes. Takes seconds.
- Lower it fast: prostaglandin drops such as latanoprost, carbonic anhydrase inhibitors such as dorzolamide, beta-blockers such as timolol, and in a crisis intravenous mannitol to pull fluid out of the eye.
- Find the cause: look for uveitis, lens position, cataract, tumour; examine the drainage angle.
- Refer: a veterinary ophthalmologist for laser cyclophotocoagulation (reducing fluid production), a drainage shunt, or in a blind, painful eye, removal or a prosthetic implant so the dog is comfortable.
Living with it
Primary glaucoma is managed, not cured. Drops buy months to years; surgery extends that; and many dogs eventually lose the first eye. The good news is that a blind eye without pain is not a tragedy for a dog, and removal of a blind painful eye is one of the happiest outcomes owners report, because the headache is finally gone. Dogs adapt to one-eyed and even no-eyed life well when the home is predictable; see 12 signs your senior dog is losing vision for the home plan.
Protecting the other eye
In primary glaucoma the fellow eye typically develops the disease within months to a couple of years. Preventive pressure-lowering drops in the healthy eye have been shown to delay onset, and a pressure check every three to six months catches a rise before it does damage. Ask for both the day the first eye is diagnosed.
Nutrition cannot lower eye pressure and no supplement treats glaucoma. What daily antioxidant and omega-3 nutrition can do is support the retina and optic nerve in the remaining eye; OcuLabs Vision Support Bites supply lutein, astaxanthin, beta-carotene and DHA for that purpose, alongside a vet's plan, never instead of it. For the other causes of a cloudy eye, read why are my dog's eyes cloudy?
Frequently asked questions
What are the first signs of glaucoma in a dog?
A red eye with a bluish cornea, a large fixed pupil, squinting, pain and vision loss on that side. The eye may enlarge within days.
How quickly can glaucoma blind a dog?
Permanent optic nerve damage can occur within 24 to 72 hours of a pressure spike.
Which breeds get glaucoma?
Primary glaucoma runs in Cocker Spaniels, Basset Hounds, Beagles, Chow Chows, Shar-Peis, Siberian Huskies, Samoyeds and Boston Terriers among others. Secondary glaucoma can affect any breed.
Can it be cured?
Primary glaucoma is controlled, not cured. Secondary glaucoma improves when the cause is treated early.
Can I protect the other eye?
Yes. Preventive drops and regular pressure checks delay onset in the second eye.
This article is general information for dog parents and is not veterinary advice. Glaucoma is a medical emergency; see a vet the same day. OcuLabs products are nutritional supplements and are not intended to diagnose, treat, cure or prevent any disease.