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When a dog has glassy eyes, we often describe it as their eyes look shiny or glazed over. Eyes are said to be a window to the soul, but they also can be a window to our health. There are many conditions in dogs that can cause glassy eyes. Veterinarian Dr. Ivana Crnec provides an insight into several. 

The Signs of Healthy Eyes in Dogs 

At a first glance, dogs’ eyes look very similar to human eyes. However, there are several crucial differences.

 First of all, dogs’ eyes are more flattened. Secondly, they are more sensitive to light and movement. Thirdly, their lens can change shape and alter the focal length, but not as good as human lens. Basically, the muscles that change the shape of the lens are weaker in dogs thus resulting in poorer near vision in dogs than in humans.

 Last but not least, dogs have larger pupils and eyes placed more laterally which ensures significantly better peripheral vision.

Under normal circumstances, a dog’s eyes should be shining, bright and free of discharge and debris. 

Because of their delicate structure and high sensitivity, the eyes can be affected by countless issues. Some conditions may cause clinical signs such as pain and vision deterioration without any visible changes. Other conditions may have visible changes. One of those visible changes is the glassy appearance of the cornea. 

Why My Dog Has Glassy Eyes?

So why does my dog have glassy eyes? Generally speaking, there are 7 causes of glassy eyes in dogs and they can be potentially serious. 


The eyeball sustains its globe shape because it is filled with a jelly-like substance called the aqueous humor. This fluid is constantly produced and must constantly be drained. If the drainage is somehow impaired, glaucoma develops.

As fluid accumulates the eyeball swells and protrudes from its socket. Over time, the eye loses its ability to see and becomes first cloudy and then glassy.

Glaucoma is diagnosed by measuring the pressure of the fluid inside the eyeball. If the pressure is higher than normal, the diagnosis is set.

The treatment includes administration of drugs that lower the intraocular pressure and laser surgery to destroy the part of the ciliary body responsible for fluid production. In advanced cases, removing the eyeball is the best option.

 Dry Eye or Keratoconjuctivitis sicca (KCS)

KCS develops when the lacrimal glands fail to produce enough tears. As a result, the eyes become dry and dull-looking. The lack of tears initially causes conjunctivitis. The risk of infection increases enormously, as does the risk of corneal damage such as ulceration. 

A little later in the course of the disease, a sticky discharge of mucus replaces the tears and becomes thick and tenacious. In many cases, a secondary bacterial infection that produces pus develops. Eventually, the eyes turn dry and opaque.

The condition can be caused by immune-mediated conditions, bacterial and viral infections, inactive adrenal glands and physical injury to the lacrimal glands.

The diagnosis is set when the vet measures the tear production with a special strip of sterile filter paper called the Schirmer test.

The treatment involves frequent administration of artificial tears.


Cataracts can develop due to many reasons but in most cases it is a normal, age-related change. Simply put, cataract occurs when the lens loses its transparency thus disabling the light to pass through. As a result, the cornea becomes cloudy or glassy and the dog loses its vision.

A vet can determine the presence of a cataract by ophtalmoscopic examination.

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Different Types of Pain in Dogs

There are different types of pain in dogs and differentiating one from another can help you better understand your companion.

The treatment of choice is surgery. However, not all patients are suitable candidates.

Chronic Superficial Keratitis or Pannus

Pannus is a form of vascular keratitis mediated by the dog’s immune system. A brown patch of pigment, which is reddened by blood vessels, develops on the cornea and if it is left untreated, will spread over the entire eye surface, eventually causing a glassy appearance.

The condition occurs in German Shepherds, Border Collies, Belgian Shepherds, Greyhounds and Siberian Huskies.

Long-term topical corticosteroids are the treatment of choice because they shrink the corneal blood vessels. In instances where long-term corticosteroid treatment cannot be administered, surgical intervention is advisable.


Inflammation of the iris and ciliary body is a painful condition called uveitis. The inflammation can be caused by immune-mediated triggers, infectious diseases, tumors, metastatic cancers and systemic fungal infections.

Usually, the pupil constricts and appears hazy. They eye is red, the third eyelid may protrude and the overall appearance of the eye becomes glassy. Namely, the signs are similar to those of glaucoma. In fact, uveitis can often develop into glaucoma.

It is important to determine the underlying condition and differentiate this condition from glaucoma.

Immediate treatment usually involves controlling the pain and suppressing the immune system with both topical and systemic corticosteroids.

 Corneal Ulcer

Generally, corneal ulcers occur as a result of trauma to the cornea. They are extremely painful and cause squinting, redness to the eye and excessive tearing. Corneal ulcers also lead to increased fluid collection in the eye which eventually leads to cloudy appearance.

Small ulcers can be revealed by dropping fluorescent dye in the eye. Larger ulcers can be seen as spots or depressions on the cornea.

In cases of ulcers, urgent surgeries are necessary to save the eye. In some cases, soft contact lenses, specially designed for a dog’s eyes, can be used as a protection. If left untreated, corneal ulcers progress and may even cause the eyeball to rupture.

 Nuclear Sclerosis

Nuclear sclerosis is a result of normal aging. Over time, in dogs aged eight years and older, the center of each lens becomes more sclerotic (harder and denser). This hardness begins to reflect light rather than refract it on to the retina. The result is an increasing bluish-gray appearance in the lenses.

It is easy to mistake nuclear sclerosis for a developing cataract. However, cataracts prevent your vet from clearly seeing the retina with an ophtalmoscope, but nuclear sclerosis does not.

If Your Dog Has Glassy Eyes, See Your Vet!

Sadly, as highly sensitive organs, the eyes are prone to a plethora of issues. If you discover a problem in one or both of your dog’s eyes, take action right away because it may be a sign of something more serious. 

An eye condition may appear minor but it could have serious repercussions if left untreated. In cases of eye issues it is advisable to see the vet the same day. And of course, see your vet right away if on top of having glassy eyes your dog is listless, refusing food and water and acting odd. 

About the Author

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.


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