Dark Spot on Dog’s Eye: 4 Reasons Why It Happens & What to Do

Dark spots in or on dogs’ eyes are not normal. Causes are multiple and include conditions such as tumors and pigmentary keratitis. They can also be simple freckles of the iris, which in some cases leads to the appearance of tumors. Contact your veterinarian if your dog’s eye becomes discolored.

Sight is one of the most important senses for dogs. If lost, dogs will scramble around for a long time until they get used to the new conditions.

That’s why it’s important to keep track of their eye health.

Many eye conditions can lead to blindness if left untreated. The appearance of dark spots on the eyes may seem insignificant, but it is not something dog owners should dismiss. A visit to the vet is mandatory.

In this article, you will learn what causes dark spots on dogs’ eyes, how to recognize the conditions, what you can do, and more.

Why Does My Dog Have a Dark Spot on Its Eye?

Dark, black, or brown spots in your dog’s eye can be hyperpigmentation of the iris (like a freckle) or of the white part of the eye. Dark spots can also be caused by severe conditions, such as tumors or pigmentary keratitis, which can lead to blindness. Take your dog to the vet for an eye exam if you notice dark spots.

Dark spots can appear in the eyes of dogs for harmless or severe reasons. 

Nevertheless, it’s not normal, so it’s important to get it checked by a veterinarian.

Here are the most common causes:

• Iris freckles
• Ocular melanosis
• Tumors
• Pigmentary keratitis

Iris Freckles (Nevi)

Dark spots on dogs’ eyes can be freckles (pigmentation). They are mostly harmless, but there are cases where they progress into something severe, such as tumors.

Increased iris pigmentation, also known as melanosis or iris freckles, is a medical condition in which a dark spot appears on the dog’s iris (the colored part of the eye). 

These spots appear after prolonged exposure to the sun and are more common in some breeds:^[1]

• Cairn terrier
• Boxer
• Labrador

The dark spots that appear on the iris may or may not change their shape and consistency over time. The freckles can develop, increasing in size. These are called nevi (plural for a nevus).

Not all pigment spots on the eyes lead to nevi. Nevi are usually harmless but they can lead to the development of tumors in some cases.

You can identify nevi by the following traits:

• Flat
• Round
• Raised above the surface of the iris

Nevi are most often well-defined without causing major changes in the iris. In other cases, nevi turn into benign (melanocytoma) or malignant (melanoma) tumors.^[2]

You should look for the following changes in your dog’s eye to identify nevi quickly:

• One or more dark small spots on the iris.
• They appear usually in one eye.
• As the condition progresses, the spots become larger.
• Change in iris color and/or shape.
• Raised iris tissue, in severe cases.

In most cases, nevi on the iris do not require treatment. If, however, they are particularly large and affect the dog’s vision, they can be removed with laser therapy.

To avoid unnecessary vision loss, take regular pictures of your dog’s eye and see if their iris freckles (dark spots) progress. 

Many eye conditions have similar symptoms, so it is recommended to examine your dog’s eyes regularly and go to the vet.

Ocular Melanosis: Brown Pigment in the White of Dog’s Eye

The brown pigment that appears in the white part of dogs’ eyes is a hereditary condition that occurs in certain breeds. It is a progressive disease that can lead to glaucoma, which in turn can cause blindness. It is not recommended to breed affected individuals.

This brown pigment in the sclera (the white of dogs’ eyes), also known as limbal melanosis or ocular melanosis, is usually harmless and hereditary. The limbus is the junction between the cornea and the sclera.^[3]

Melanosis is an abnormality in the development of the anterior surface of the protein of the eyeball (sclera).

It mainly affects Cairn terrier dogs but can also affect Boxers and Labradors. It usually affects both eyes and occurs around the age of 5-11 years. 

Dogs with this condition should not be bred.

This condition is also called pigmentary glaucoma because it can progress to glaucoma. The pigment cells (melanocytes) that accumulate in the sclera clog the drains that remove fluids from the eye. 

This leads to increased intraocular pressure (glaucoma) which damages the retina and optic nerve, causing blindness.

Ocular melanosis can appear on the entire surface of the eye, not only on the sclera.^[4]

Ocular melanosis symptoms:^[5]

• Brown spots in the eye, especially in the white part
• Bloodshot eyes
• Cloudy eyes (glaucoma)
• Bulging eyes
• Excessive tearing
• Pain
• Photosensitivity

Ocular melanosis has no treatment. Vets can recommend anti-inflammatory drugs, analgesics, and medications that decrease fluid production. Sometimes laser therapy is also recommended.

Tumors

Tumors that lead to dark spots on the eyes have several development causes. They can be new tumors or evolve from other eye conditions (such as nevi). Eye tumors can also be metastases of other tumors in the body.

Eye tumors can be malignant and benign. These tumors can appear from many things:^[6]

• Acquired primary ocular melanosis
• Nevi
• De novo (new tumor)
• They can be metastatic lesions

Ocular melanomas are of two types:

• Uveal
• Limbal

Uveal melanoma

Uveal melanoma tumoral masses develop from previous conditions of the iris or ciliary body or be a new tumor. The mass can protrude or deform the pupil, causing blood vessels to break. 

Dogs often experience eye pain if they develop uveal melanoma.

It is the most common type of tumor found in the eye in dogs and can be both malignant and benign. It has a metastasis rate of only 5% of cases. In approximately 80% of cases, the tumor is non-cancerous (benign).^[7]

The final stages of uveal melanoma in dogs include the following symptoms:

• Bleeding
• Detachment of the retina
• Glaucoma

This type of melanoma is most often seen in Labrador retrievers.

Limbal (epibulbar) melanoma

Limbal melanoma tumors are mainly observed as a circular mass (pigmented on the cornea) directed towards the inside of the eyeball. 

Affected dogs can have pigmented spots on their eyes (especially on the sclera) and excessive tear production. Conjunctival irritation can also occur.

German shepherd and Labrador retriever females are the most prone to developing this type of cancer. The average age of development is 5-6 years. Limbal melanomas are often benign.

Treatment of eye tumors often involves removing the affected eye. Sometimes the treatment can consist in removing the tumor through laser surgery or excision.

Pigmentary Keratitis

Dark spots on dogs’ eyes can also be caused by Pigmentary keratitis. It is often caused by inflammations and irritations that (mechanically) traumatize the eye. It can also have a genetic component.

Pigmentary keratitis is caused by the deposition of melanin granules on the surface of the eye. It appears as a brown-black spot.

Brachycephalic dogs are more prone to develop this medical condition:

• Pugs
• Bulldogs
• Boxers

Pigmentary keratitis is caused by many things:

• Genetic factors
• The facial conformation of these breeds
• Chronic eye irritation
• Eye inflammation

In cases of chronic inflammation, melanin is deposited in the deep layers of the cornea. Eye inflammation can occur due to eyelid conditions:

• Entropion (eyelids turned inside the eye)
• Ectropion (eyelid turned to the outside of the eye)
• Abnormal growth of eyelashes
• Tumors

All these conditions can cause trauma and damage to the surface of the eye.

Pigmentary keratitis is often associated with keratoconjunctivitis sicca (dry eyes). This leads to poor tear production, so the eye is not properly lubricated. Affected dogs will have abnormal blink reflexes.

In other cases, even after the main cause has been addressed and treated, pigmentary keratitis continues to form. This suggests a genetic component.^[8]

The treatment of pigmentary keratitis is based on removing the cause that led to its development. Eyelid abnormalities and tumors are usually surgically repaired or removed, while eye inflammations are treated with appropriate medication. 

These therapies could stop the deposition of pigment in the cornea.

Related: White Spots on Dog’s Eyes