The Alarming Condition That Can Make Your Dog’s Eyes Cloudy

Analysis by Dr. Karen Shaw Becker

corneal dystrophy

Story at-a-glance -

  • Corneal dystrophy is a genetic, progressive condition in dogs that usually affects both eyes; the condition rarely occurs in cats
  • There are three forms of corneal dystrophy: epithelial, stromal, and endothelial; diagnosis is best handled by a veterinary ophthalmologist and treatment depends on the type and severity of the condition
  • Other eye conditions that can cause cloudy eyes include nuclear sclerosis, cataracts, glaucoma, and anterior uveitis

There's an eye condition that occurs in dogs that many pet parents have never heard of. It's called corneal dystrophy and is usually diagnosed after an owner or veterinarian notices that a dog's eyes appear cloudy. The condition is rarely seen in cats. Corneal dystrophy is an inherited (genetic), progressive condition that usually affects both eyes. It can develop in pets from 4 months to 13 years — the age of onset depends on the form the disease takes.

Depending on the location of the clouding within the layers of the cornea and the severity of the condition, corneal dystrophy can progress to blindness or corneal ulceration, which can cause severe pain and loss of the eye. Otherwise, the condition isn't painful.

Three Types of Corneal Dystrophy

There are three types of corneal dystrophy, depending on the location:

  • Epithelial corneal dystrophy, which affects cell formation
  • Stromal corneal dystrophy, which causes the cloudy blue appearance
  • Endothelial corneal dystrophy, which affects the cells of the lining of the cornea

Epithelial corneal dystrophy is a slowly progressing form of the disease resulting from degenerative or innate abnormalities of the cornea. The usual age of onset is 6 months to 6 years and the condition is seen most often in Shetland Sheepdogs. Noticeable changes to the eyes are white or gray circular or irregular opacities or rings on the cornea. There can also be corneal spasms, but the dog's vision remains unchanged.

Stromal corneal dystrophy is also the result of innate abnormalities of the cornea, typically occurs in young adult dogs, and is characterized by white, gray or silver oval or circular opacities. Vision usually remains normal but may be compromised in the presence of advanced diffuse opacity. Dog breeds predisposed to both epithelial and stromal corneal dystrophies include:

Afghan hound

Lhasa apso

Airedale terrier


Alaskan malamute

Miniature pinscher

American cocker spaniel

Rough collie


Siberian husky

Bearded collie


Bichon frise


Cavalier King Charles spaniel


German shepherd

Endothelial corneal dystrophy is the result of degeneration of the lining of the cornea and typically occurs in middle-aged or older dogs, and in females more often than males. With this form of the disease, the cornea swells and develops fluid blisters. Vision may be reduced in advanced cases. Breeds predisposed to endothelial corneal dystrophy include the Boston Terrier, Chihuahua, and Dachshund.

Diagnosing Corneal Dystrophy

In diagnosing corneal dystrophy, veterinarians typically take a health history, perform a thorough physical exam including an eye exam, order a complete blood count, blood chemical profile, electrolyte panel and urinalysis. Since it's very important to distinguish corneal dystrophy from other corneal diseases that look similar but are non-genetic, inflammatory, or purely degenerative, dogs are often referred to a veterinary ophthalmologist for a final diagnosis.

A technique called slit lamp microscopy is what veterinarians and veterinary ophthalmologists use to determine the type of corneal dystrophy present, and a fluorescein stain will be used to check the eye for abrasions, and to evaluate the shape of the cornea. Fluorescein dye will also reveal corneal ulcers, which occur with the endothelial and epithelial forms of the disease.

The dye is less useful in diagnosing the endothelial and stromal forms of corneal dystrophy but is helpful in diagnosing the epithelial form. A tonometer will also be used to measure the interior pressure in the eyes as a way to rule out glaucoma as the cause of corneal swelling.

Treatment Options

Dogs with corneal ulcers are treated with a variety of eye medications. Typically, stromal corneal dystrophy doesn't require treatment. Endothelial corneal dystrophy is sometimes treated by fitting contact lenses over the eyes. Epithelial corneal tags, when present, may be removed.

Another treatment option for endothelial corneal dystrophy is flap surgery of the conjunctiva. Corneal transplants are performed occasionally, but the results are inconsistent.

A dog with corneal dystrophy will usually have some eye cloudiness even after successful treatment of the condition. And since corneal ulcers are common with both endothelial and epithelial corneal dystrophy, dogs with pain or blinking or watering of the eyes should be seen by a veterinarian.

Other Diseases That Can Cause Cloudy Eyes in Pets

Nuclear sclerosis — Nuclear sclerosis, also called lenticular sclerosis, can cause the pupils of your dog's eyes to take on a cloudy bluish-gray appearance. The condition is also seen in humans and horses.

Nuclear sclerosis is a normal change to the lenses of the eyes that typically occurs in dogs over the age of six. It usually develops in both eyes at the same time, and the good news is, it isn't painful. Because nuclear sclerosis comes on gradually, your dog should be able to comfortably adapt to any minor changes in vision that occur.

Cataracts — Cataracts form a blue cloud of varying degrees inside the capsule that holds the lens of the eye. Cataracts can progress very slowly over many years or they can come on very quickly, leading to blindness within a few days or weeks. Cataracts in dogs are often inherited. They can also be caused by diabetes, toxicity from drugs and pest preventives, another underlying eye disease, trauma to the eye, nutritional deficiencies in puppies, and as part of the aging process.

If your dog is diagnosed with cataracts, less troublesome ones will be rechecked periodically to see if they're progressing. Sometimes anti-inflammatory eye drops are prescribed. But if your pet's vision is affected, her quality of life is compromised, or the cataracts are progressing rapidly, surgery is sometimes recommended to restore vision.

Glaucoma — Glaucoma is a condition in which there is increased pressure within your dog's eye. The fluid produced inside the eye isn't draining properly, which causes a buildup of painful pressure within the eye. If the fluid buildup (which is what causes the cloudy blue appearance) and pressure are left untreated, they will cause the eye to enlarge and become misshapen, and the eventual result will be irreversible blindness.

In pets, glaucoma is either primary or secondary. Primary glaucoma is inherited and typically starts in one eye, but in most cases, it will eventually involve both eyes. Secondary glaucoma occurs when other eye diseases are present, including uveitis, advanced cataracts, cancer of the eye, lens displacement, and chronic retinal detachment.

Treatment will depend on the cause and severity of the disease. But the goal is always to alleviate the pressure inside the eye as quickly as possible by reducing the production of aqueous humor and increasing drainage from the affected eye. Unfortunately, medical treatment of the condition is not nearly as successful with pets as it is with people. Long-term control of primary glaucoma in a blind eye is usually removal of the eye. As awful as it sounds, it actually provides the very best relief for the dog.

Anterior uveitis — If your dog has anterior uveitis, it means there is inflammation of the iris and ciliary body within the uvea of the eye. The disease is also known as iridocyclitis, and it is a quite painful condition that can ultimately threaten a dog's vision. Because of the uvea's rich blood supply, it's a natural target for problems that originate in other parts of a dog's body. Uveitis is a common secondary condition that results from a disease process elsewhere in the body.

Anterior uveitis causes pain in the eyes. There may also be squinting, pawing at the eyes, eye redness, excessive tearing or discharge, change in the appearance of the pupil, change in the shape or color of the iris, swelling of the eyeball, or a dull or cloudy-looking eye.

Treatment will depend on the diagnosis. The condition should be treated aggressively to prevent further damage to the eye. In every case, regardless of the cause of uveitis, eye drops and ointments are prescribed, along with medications to manage pain and inflammation. If an infection is present, the appropriate medication will be prescribed. Very rarely, surgery to remove the eye is necessary to resolve an underlying tumor that's causing secondary disease like glaucoma.

If you notice your dog's eyes are becoming cloudy or taking on a bluish tint, it's very important to make an appointment with your veterinarian. Some conditions that cause blue eyes are harmless, painless, and have little or no effect on a dog's vision. But I recommend you have your canine companion's eyes examined as soon as possible to determine exactly what's going on, and whether treatment is needed.

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