Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: A cataract is a cloudiness in the lens of the eye that blocks light and can lead to blindness. In dogs, cataracts are often inherited or caused by diabetes, which can cause them to form within weeks. They’re different from nuclear sclerosis, the normal bluish-gray haze of aging that doesn’t significantly affect vision. Surgery by a veterinary ophthalmologist is the only way to remove a cataract and restore vision. No eye drop has been proven to dissolve cataracts in dogs.
Signs
- A white or cloudy appearance in the pupil
- Bumping into things, especially in dim light or new places
- Hesitating on stairs or jumping
- Squinting, redness, or rubbing the eye (signs of inflammation)
Cataracts vs. nuclear sclerosis
Most older dogs develop a bluish-gray haze in the lens called nuclear sclerosis. It’s a normal aging change, and most dogs see fairly well with it. Cataracts are usually whiter and more opaque, and block vision. An eye exam tells them apart.
Causes
- Inherited cataracts: common in many breeds, sometimes appearing in young dogs
- Diabetes mellitus: most diabetic dogs develop cataracts, often within the first year
- Aging
- Eye inflammation (uveitis), trauma, or retinal disease
Why cataracts need monitoring
As cataracts develop, proteins leak from the lens and inflame the eye (lens-induced uveitis). Untreated, this can lead to painful glaucoma, lens dislocation, or retinal detachment. Your vet may prescribe anti-inflammatory eye drops to protect the eye, even if surgery isn’t planned.
When to see a vet
See your vet for any new cloudiness or vision changes. Go promptly for a red, painful, squinting eye, or sudden cloudiness, especially in a diabetic dog.
Treatment
- Cataract surgery (phacoemulsification): the cloudy lens is removed and usually replaced with an artificial lens. In good candidates, surgery restores functional vision in most dogs.
- Pre-surgery testing checks that the retina works (electroretinography) and that the eye is healthy enough.
- Anti-inflammatory eye drops to control inflammation, with or without surgery.
- Controlling diabetes before surgery in diabetic dogs.
Living with a dog with low vision
- Keep furniture and food and water bowls in the same places.
- Block stairs and pools.
- Use your voice before touching your dog.
- Use scent markers or textured rugs to mark key areas.
- Walk on a leash in unfamiliar places.
Dogs rely heavily on smell and hearing, and most adapt well to vision loss.
What to avoid
- Eye drops claiming to dissolve cataracts (such as lanosterol or N-acetylcarnosine products): not proven to work in dogs.
- Human eye drops or leftover medications.
- Ignoring a red or painful eye.
Frequently asked questions
Can cataracts in dogs be reversed without surgery?
No. Surgery is the only proven treatment.
Is my dog too old for cataract surgery?
Age alone isn’t a barrier. Overall health and eye health matter more.
Do cataracts hurt?
The cataract itself doesn’t, but the inflammation it can cause may be painful.
Sources
- Merck Veterinary Manual: Cataracts in dogs
- Beam S, et al. A retrospective-cohort study on the development of cataracts in dogs with diabetes mellitus: 200 cases. Vet Ophthalmol. 1999
- American College of Veterinary Ophthalmologists (ACVO): Cataracts
- Gelatt KN (ed.). Veterinary Ophthalmology. Wiley-Blackwell
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.