What Causes Glaucoma in Dogs?
📝 Summary
Canine glaucoma comes in primary and secondary forms. Primary glaucoma is a hereditary drainage-angle defect that blocks fluid outflow and raises eye pressure; it is common in Huskies, Chow Chows, Poodles, Cocker Spaniels, Beagles, and Maltese, usually appearing at 4–9 years. Secondary glaucoma follows eye disease such as uveitis, pupil blockage, lens luxation, or tumors. Treatment aims to lower pressure and save vision—medication works best early, but surgery is often needed later. Because early signs are subtle, at-risk breeds should have annual eye-pressure checks.
1 Causes of Canine Glaucoma
Primary glaucoma: underdevelopment or arrested development of the iridocorneal angle blocks drainage of the aqueous fluid, raising intraocular pressure. It is relatively common in Siberian Huskies, Chow Chows, Poodles, Cocker Spaniels, Beagles, and Maltese, with onset usually between 4 and 9 years of age.
Secondary glaucoma: caused by eye diseases such as anterior uveitis, pupil blockage or closure, lens luxation, or eye tumors, which impair fluid drainage and increase eye pressure.
2 Diagnosis and Symptoms
Early signs are mild—tearing, slight blepharospasm, conjunctival redness, a reactive pupil, little or no pain, and unaffected vision. As the disease progresses, pressure rises, the eyeball enlarges, and vision weakens; from the side you may see the eye bulge forward, and the globe feels hard on finger pressure. Eventually the dog goes blind, walks unsteadily, and may bump into walls.
Structurally caused primary glaucoma is seen mainly in Huskies, Chow Chows, and Poodles; lens-luxation secondary glaucoma is more common in Boston Terriers, Dalmatians, and West Highland White Terriers.
3 Treatment and Prevention
The goal of treatment is to lower intraocular pressure, reduce tissue damage, and preserve vision. Options include IV 20% mannitol to raise blood osmolarity and reduce aqueous fluid; carbonic anhydrase inhibitors (dichlorphenamide, acetazolamide, methazolamide) to suppress fluid production; 1–2% pilocarpine to open the angle and improve circulation; and iris implantation to create a new external drainage pathway.
Pressure-lowering medication works best early; later it becomes ineffective, and earlier treatment better preserves vision. Medication also carries a risk of worsening the condition, so surgery is often the best way to prevent blindness.
Glaucoma is more common in older dogs and certain breeds, and the risk rises with age. Some breeds have inherited drainage-angle defects and can be affected even when young. Dogs with severe eye trauma, eye disease, or retinal detachment are also vulnerable. Because early and mid-stage signs are so subtle, annual intraocular-pressure checks are important for at-risk breeds.
Want to learn more about pet health?
Explore our pet health channel for more science-based care guides
Read More Articles →