Cloudy Eyes in Dogs: Causes and When to Worry

Is a Cloudy Eye an Emergency?

Usually not urgent: a gradual, even bluish-gray haze in both eyes of an older dog that sees well and isn't bothered. That's typical of nuclear sclerosis, though it's still worth mentioning at the next checkup.^1,2

Same day: cloudiness that appears suddenly, affects one eye, or comes with redness, pain, squinting, discharge, a change in pupil size or vision loss.^3,4,6

Causes of Cloudy Eyes in Dogs

• Nuclear sclerosis: normal aging of the lens. Both eyes, bluish-gray, painless.^1,2
• Cataract: a white or white-blue opacity in the lens that can block vision.^15,16
• Corneal ulcer or scratch: a painful, squinting eye, sometimes with a cloudy spot or haze on the surface.^5,10
• Glaucoma: a bluish, hazy cornea with a red eye and a large pupil. An emergency.³
• Uveitis: inflammation inside the eye causing redness, pain, cloudiness and often a small pupil.⁴
• Corneal swelling (edema) in older dogs: the cells that keep the cornea clear decline with age; Boston Terriers, Chihuahuas and Dachshunds are predisposed.^11,17
• Corneal dystrophy and lipid deposits: white, sparkly or ring-shaped spots on the cornea, often in both eyes. Usually painless.^17,5
• Dry eye: long-standing dry eye causes thick discharge and gradual scarring and pigment that can dull the cornea.¹⁸

Nuclear Sclerosis

Nuclear (lenticular) sclerosis is a normal hardening of the lens with age. It gives both pupils a smooth, bluish-gray look, usually from about 6 years of age.^1,12,2 Vision isn't significantly affected, and no treatment is needed.^2,1 During an exam, your vet can still see the back of the eye through a sclerotic lens, which isn't possible through a dense cataract.^2,11

Cataracts

A cataract is a disease change in the lens that can grow until it blinds the eye. Most are inherited, and diabetes is the most common disease cause.¹⁵ Leaking cataracts can cause painful inflammation and glaucoma, so they need monitoring even if you don't choose surgery.^8,19 See cataracts in dogs.

Cornea Problems

The cornea is the clear front window of the eye. When it's injured or swollen it turns hazy or blue.⁵ Ulcers are painful and need a stain test; deep or "melting" ulcers can worsen within a day.^10,6 See corneal ulcers in dogs. Glaucoma also makes the cornea cloudy and blue, along with a red eye and a large pupil.³ See glaucoma in dogs.

Why Is My Dog's Eye Turning Blue?

A blue haze usually means the cornea is swollen. Causes include glaucoma, ulcers, uveitis, injury and age-related corneal changes.^3,5,11 In young dogs, a blue cornea can follow infection with canine adenovirus type 1 (infectious canine hepatitis); older live vaccines containing this virus occasionally caused it. Modern vaccines use a related virus that rarely does, and the clouding usually clears on its own.²⁰ Any young dog with a blue eye should still be examined, and urgently if it's red, painful or the dog seems ill.^20,4

Don't confuse a blue haze with naturally blue eyes or with the green, yellow or red "glow" in photos, which is a normal reflection from the reflective layer at the back of the eye. A white pupil in one eye in photos, though, warrants an exam.²¹

How Vets Find the Cause

• Fluorescein stain to check for an ulcer^10,5
• Eye pressure (tonometry) to check for glaucoma or uveitis; pressure is high in glaucoma and often low in uveitis^3,4
• Tear test for dry eye¹⁸
• Dilated eye exam to tell nuclear sclerosis from a cataract and to look at the retina¹

Your vet may refer your dog to a veterinary ophthalmologist for more detailed tests.^15,22

Frequently Asked Questions

Why is my dog's eye cloudy?

In older dogs, a haze in both eyes is usually nuclear sclerosis. Other causes include cataracts, corneal ulcers, glaucoma, uveitis, corneal swelling and dry eye.

Is a cloudy eye in a dog an emergency?

It is if it's sudden, in one eye, or comes with redness, pain, squinting, a large pupil or vision loss. A gradual haze in both eyes of an older dog usually isn't urgent.

Can a cloudy eye in a dog go away?

Some do: cloudiness from a healing ulcer or treated uveitis often clears. Nuclear sclerosis and cataracts don't go away, though cataracts can be removed surgically.

At what age do dogs get cloudy eyes?

Nuclear sclerosis usually starts around 6 years of age. By 13, essentially all dogs have some lens cloudiness from nuclear sclerosis or cataracts.

How can I tell cataracts from nuclear sclerosis?

Nuclear sclerosis is an even bluish-gray haze; cataracts are usually whiter and patchier. Only a dilated eye exam can tell them apart reliably.

Can I use eye drops for my dog's cloudy eye?

Not without a diagnosis. Some drops, especially steroids, can make an ulcer much worse. Use only what your vet prescribes.

Why is my dog's eye turning blue?

Usually corneal swelling from glaucoma, an ulcer, uveitis or injury. In puppies it can follow canine adenovirus infection. Have it checked promptly.

Does a cloudy eye mean my dog is blind?

Not necessarily. Dogs with nuclear sclerosis see fairly well. Mature cataracts, glaucoma and severe uveitis can cause blindness.