What Causes a Blue Eye in Dogs?

A blue eye in dogs is not a common occurrence, but it can happen. In most cases, the blue eye is a result of corneal edema, or when there is excess water in the cornea secondary to a disease process. The blue eye may be accompanied by other symptoms, such as discharge from the eyes or excessive tearing. If you notice that your dog has a blue eye, it is important to take him to the veterinarian for an evaluation. Continue reading to learn more about the causes of a blue eye in dogs.

Corneal edema is often the cause of a blue eye in dogs

The cornea is the clear, outermost layer of the eye. It is responsible for protecting the inner structures of the eye and helps to focus light. The cornea is made up of several layers, including the epithelium, stroma, and endothelium. The epithelium is a thin layer of cells that covers the surface of the cornea.

When fluid accumulates within the stroma of the cornea as a result of damage to the endothelium, it is called corneal edema. When this happens, the light that enters the eye is scattered, which gives the cornea a blue appearance.

Below we will discuss the most common causes of corneal damage that will result in corneal edema and a blue eye in dogs.

1. Inherited endothelial dystrophy/Corneal dystrophy

Endothelial corneal dystrophy is an inherited disease that affects the endothelium of the cornea. The endothelium is a single layer of cells that helps to pump fluid out of the cornea. When this layer of cells is damaged, fluid starts to accumulate in the stroma, leading to corneal edema and a blue eye in dogs.

Corneal edema severity can range from mild and slow-progressing to rapidly progressive and severe. An area of focal edema is usually noted at first, then the edema spreads and becomes more widespread. Both eyes are often affected concurrently.

Dogs that suffer from corneal edema are mostly middle-aged when it is first identified. Commonly affected breeds include the Boston terrier, boxer, dachshund, chihuahua, and German shorthair.

2. Glaucoma

Glaucoma is a condition in which the pressure in the eye is increased and can result in a blue eye in dogs. An increase in intraocular pressure results in a pressure gradient that is too high for the normal endothelial pumping mechanism to overcome, resulting in corneal edema. If intraocular pressure is normalized, the corneal edema will disappear within hours.

3. Lens luxation

Anterior lens luxation is a condition in which the lens of the eye becomes dislocated from its normal position. This can occur as a result of trauma or due to glaucoma where the increased intraocular pressure dislocates the lens. When the lens is displaced, it puts pressure on the cornea and iris, which can lead to corneal edema and a blue eye in dogs.

4. Trauma

Corneal trauma is another common cause of corneal edema and a blue eye in dogs. Trauma can occur from a foreign body such as a plant or branch, or it can be the result of an injury during rough play.

5. Inflammatory conditions

Anterior uveitis is the most frequent inflammatory cause of corneal edema. Anterior uveitis is an inflammation of the iris and/or ciliary body. This can be caused by a variety of things such as infection, autoimmune disease, or trauma.

Corneal edema secondary to anterior uveitis usually affects one eye at first, but can eventually affect both eyes. The blue appearance of the cornea is usually a result of the inflammation and not the edema itself.

Treatment options for a blue eye in dogs

There is no cure for corneal endothelial disease, but treatments are available to improve or stabilize the corneal edema and make the eye more comfortable. These therapies aim to address the underlying condition causing the disease.

The most common treatment for corneal edema in dogs is topical sodium chloride (NaCl 5%). In dogs, topical NaCl 5% can initially reduce corneal thickness, but the effect is not permanent. With or without treatment, the corneal endothelial disease usually gets worse and may eventually cause a painful corneal ulcer.

In summary, a blue eye in dogs is often a result of corneal edema. Common causes of corneal edema or a blue eye in dogs include endothelial corneal dystrophy, glaucoma, lens luxation, trauma, and inflammatory conditions. If you notice that your dog has a blue eye, it is important to see your veterinarian so that the underlying cause can be treated.