Black or Brown Spots in My Dog’s Eye – 7 Causes and What To Do

Recently, a client brought her Boston terrier to the clinic because she noticed a small black disc at the bottom of her pup’s eye. It was a few millimeters in diameter and didn’t seem to affect her dog’s vision. After examination, I explained the condition was benign and probably shouldn’t cause any problems. There are several causes for brown or black spots in dog eyes. While some are benign, others are quite serious. In this article, we’ll explain the different conditions that lead to brown or black discoloration in the eye, how they’re treated, and when you need to be concerned about the spots.

Should I be concerned about brown or black spots in my dog’s eye?

Finding a spot or fleck on your dog’s eye can be shocking. But should you be concerned? Sometimes yes, sometimes no. Some dogs are born with spots of black or brown hyperpigmentation in their eyes. But other dark areas point to cancer or other serious conditions like corneal ulcers or glaucoma.

7 frequent causes of brown or black spots in dogs’ eyes

Let’s look at the most common causes of brown or black spots in dogs’ eyes.

1. Neviv (Iris freckles)

Some dogs can develop areas with increased pigment in the iris. They can be caused by UV light exposure or arise due to a genetic predisposition. Usually, these freckles are benign, but if they grow larger, they may affect your pup’s eye or vision. Smaller nevi can increase in size and become a flat or rounded spot known as a nevus. Occasionally, nevi become tumors.

Treatment for nevi is usually not necessary. However, you should monitor your pooch for any changes. Tell your veterinarian about any growth in size, loss of vision for your dog, or other concerning symptoms.

2. Eye cysts

Eye cysts may be congenital or arise as a result of trauma or inflammation. They’re black, fluid-filled discs that are often only a few millimeters in diameter. The lesions can appear in the iris, choroid, or ciliary body. Not usually affecting your dog’s vision, iris cysts tend to be painless.

As with nevi, iris cysts rarely require treatment. If the discs affect your pup’s vision, they can be surgically deflated or aspirated. However, this requires an ophthalmologic specialist. View more pictures of eye cysts in dogs.

3. Ocular melanosis

Certain breeds, including Cairn terriers and Boxers, can develop a build-up of melanocytes in some layers of the eye such as the iris and sclera. The cells clog the normal drainage system in the eye, so the intraocular pressure increases. As a result, secondary glaucoma develops and can lead to blindness.

In addition to brown spots in the eye, signs of ocular melanosis include:

• Bloodshot eyes
• Bulging eyes
• Cloudy cornea
• Excessive tearing
• Light sensitivity
• Loss of appetite

There is no cure for ocular melanosis. Medical management with anti-inflammatory drugs and analgesics may help reduce pain and inflammation. In some cases, laser surgery by a specialist may help decrease the production of aqueous fluid in the eye. If your dog doesn’t respond to treatments, surgical removal of the eye may be necessary.

4. Pigmentary keratitis

Chronic eye inflammation can cause brownish-black spots in the eye from a deposit of melanin granules. Most commonly seen in brachycephalic breeds, this condition is often linked to dry eyes. Signs of pigmentary keratitis include:

• Flat brown spot in the cornea 
• Bloodshot white of the eye 
• Reddened conjunctival membranes
• Eye discharge

Treatment for pigmentary keratitis is directed at the underlying cause and may include artificial tears or surgical repair of eyelid abnormalities. The spots are usually not reversible, but they may fade over time.

5. Ocular melanoma/tumor

When melanocytes grow uncontrollably in the uvea or limbus, they can clump together in a mass of cells. Although the growths are often benign, they cause considerable pain and inflammation. Long term, melanomas can lead to glaucoma, retinal detachment, and cataracts. Symptoms include:

• Brown or black spots on the iris that may be raised or flat
• Intraocular bleeding
• Dark mass inside the eye that protrudes through the pupil
• Redness
• Rubbing the eye
• Excessive tearing

Without treatment, the mass will continue to grow and cause pressure build-up in the eye. Treatment options for ocular melanoma vary depending on the tumor’s extent and include:

• Laser surgery
• Partial removal of the iris
• Enucleation

6. Allergy/Infection

When some dogs have an allergic reaction to environmental or food allergens, they develop brown spots on their eyes from the inflammation. This symptom may also be present with certain eye infections such as uveitis. Other symptoms you may notice with eye allergies or infections include:

• Reddened or bloodshot sclera
• Watery eye
• Discharge
• Blinking or squinting
• Pawing at the face/eye

To treat allergies, your veterinarian will recommend lifestyle changes to avoid the allergen if possible. This may involve feeding a hypoallergenic diet, changing your dog’s bedding, and doing a deep cleaning of the house. The doctor will also prescribe antihistamines and possibly steroidal eye drops to reduce inflammation. If your pooch has an eye infection, your vet will treat it with oral or ophthalmic antibiotics. 

7. Horner’s Syndrome

With Horner’s syndrome, the sympathetic nerves to one eye suddenly stop functioning properly. As a result, dogs will have symptoms in the affected eye:

• Drooping upper eyelid
• The pupil is constricted/small
• Eye appears sunken
• The third eyelid is red and may be elevated/raised

Many times, Horner’s syndrome in dogs has no known cause(idiopathic) and tends to resolve in 6-8 weeks. If the condition is triggered by an infection, injury, or mass and is characterized as preganglionic, the prognosis is guarded. 

There is no cure for idiopathic Horner’s, but if there’s an identifiable cause, your veterinarian will treat the underlying condition.

When are black or brown spots in my dog’s eye a cause for concern?

Many conditions that cause black or brown eye spots share similar symptoms, so it can be challenging to tell the difference between harmless conditions and serious health threats. If you notice new spots in your dog’s eye(s), you should contact your veterinarian and discuss your findings. 

Take your dog to the vet if you observe symptoms like:

• Bumping into furniture or walls
• Red, bloodshot, or swollen eyes
• Rubbing the eyes
• Squinting or sensitivity to light
• Anxiety or hesitation in unfamiliar surroundings
• Bulging eyes

Can new spots on my dog’s eyes be cancer?

Brown or black spots can be a sign of a cancerous tumor. When melanocytes clump together in your dog’s uveal tract, the growth is usually benign. However, the growths occasionally become malignant if they’re left alone. If you notice new brown or black spots in your pup’s eye, you should consult with your veterinarian to rule out the possibility of cancer.

Learn more about Spots in Dog’s Eyes (with pictures and veterinarian advice).