Glossary

Glaucoma

Raised pressure inside the eye that damages the optic nerve; it is painful and can cause permanent blindness within hours or days.

Also called: canine glaucoma, high eye pressure, raised intraocular pressure

Glaucoma is a build-up of pressure inside the eye because fluid cannot drain properly. The pressure damages the retina and optic nerve, and it hurts, a bit like a severe headache. Signs include a red eye, a cloudy or bluish cornea, a wide pupil, squinting, tearing, rubbing the eye and a dog that is quiet or off its food.

Primary glaucoma is inherited and appears in breeds including the Cocker Spaniel and Basset Hound. Other eye disease, such as inflammation or a displaced lens, can cause secondary glaucoma.

Acute glaucoma is an emergency, since vision can be lost within a day or two. Any painful, red or cloudy eye needs a vet the same day. Eye drops bought without advice can make some eye problems worse.

Last reviewed November 8, 2026

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