The eyes are precious windows into the world, and gazing into your dog’s eyes connects you with their soul giving you a glimpse of their undying loyalty and love. Other than wagging its tail, your dog’s eyes are constantly telling you something- that it’s excited, ready for a treat, or is feeling unwell.
But while gazing, have you noticed a brown spot in their eyes? It could be something minor like pigmentation or a more serious health concern that requires immediate veterinary attention.
Many eye conditions are degenerative and can quickly lead to vision loss if not detected early enough. So, when it comes to your four-legged best friend’s eyes, it’s much better to be safe than sorry!
Our guide provides expert details about the causes of a brown spot in your dog’s eyes to help you understand what normal pigmentation is and when to seek professional intervention.
Why Is There A Brown Spot In My Dog’s Eyes?
Your furry companion instinctively hides their pain and discomfort, including eye pain. Dogs lose up to 80% of their vision before making noticeable visual errors. So this means that dog owners will likely discover their pups have an eye problem when the disease has progressed.
Many canine eye problems start with a color change within or across the eye surface and typically progress to physical and behavioral signs that depict eye trouble. These include squinting, tearing, excessive blinking, discharge, and eye rubbing.
If your dog has a brown spot in its eyes that’s not changing in color or size, it is most likely natural pigmentation.
However, pigmented spots in senior dogs are thought to occur with environmental factors (iris freckles from sun exposure common to Labradors, Boxers, and Cairn Terriers) or genetic origin (ocular melanosis). The main explanation is either pigmentary keratitis or eye/ocular melanoma.
Pigmentary keratitis/keratopathy is grouping melanocytes (pigment-rich melanin granules) onto the cornea. The condition is harmless, but the causes are diverse and must be investigated to provide the appropriate treatment.
In contrast, eye melanoma is a cancerous tumor in the eye that results from the uncontrolled proliferation of melanin granules (melanocytes). It can be benign (grows in size) or malignant (grows in size and spreads).
Benign tumors are generally harmless though they can grow in size and pressure critical body organs affecting normal functions. Mostly, it’s malignant tumors that you should worry about- they are life-threatening and require urgent medical care.
It’s best to consult a veterinarian or canine ophthalmologist if your dog has a brown spot in its eye to rule out any severe issue like melanoma. Also, the earlier you start your dog on treatment, the better the prognosis for complete recovery.
Brown Spot In My Dog’s Eye – Pigmentary Keratitis Vs. Eye Melanoma
So, how can you tell whether the brown spot in your dog’s eyes is a sign of pigmentary keratitis or eye melanoma? Here are the distinct symptoms that indicate the presence of each condition.
Pigmentary Keratitis:
- The spot is flat
- You have a flat-faced dog (brachycephalic breed) such as a Terriers, Pug, and Bulldogs
- The size is ideally the same
- Situated in the cornea ((the clear transparent section on the front of the eye) or the white part of the eye (sclera).
- Tearing and ropy discharge
Eye/Ocular Melanoma:
- The spot is raised and round
- It increases in size as the condition progresses; in severe cases, the iris tissue is raised
- Distinct boundaries around the spot
- Situated in the limbus or uvea (ciliary body, choroid, or iris)
- Prevalent in highly pigmented breeds such as Golden Retriever, Schnauzer, Cocker Spaniel, and German Shepherd
- Squinting, rubbing of the eye, and head shaking
More About Pigmentary Keratitis In Dogs
Pigmentary keratitis, also known as corneal melanosis, can appear as a brown or black discoloration on the cornea. Your dog’s eye will look like mud on a windshield.
Pigmentary keratitis can affect one or both eyes and may be accompanied by pain, chronic inflammation, and cornea scarring leading to impaired vision. The brown spot results from the congregation of melanocytes (melanin-producing cells) on the cornea.
Clinical Signs Of Pigmentary Keratitis
Most dog owners only notice there’s a problem with their dog’s eyes when they become visually impaired. The most notable sign of pigmentary keratitis is a dark brown blotch covering the cornea either in one eye or both eyes.
Furthermore, the discoloration is visible in normal light or upon closer observation using special detecting equipment. Other signs include thick, ropy discharge, redness of the conjunctiva, pain, dry-appearing cornea, enlargement of the eye, and tearing.
How Do Dogs Get Pigmentary Keratitis?
Pigmentary keratitis can be caused by genetics or chronic inflammation, infection, or irritation of the eyes due to environmental, structural, and infectious conditions. As a result of chronic inflammation, melanosomes (pigment granules) can be deposited in the cornea’s inner layer, causing a faint brown-to-dark film.
The condition is more prevalent in flat-faced dogs because of their facial structures- wide eyelid openings and protruding eyes that expose them to injury, infections, and inflammation. Similarly, canines with long hair across their faces, like Poodles, Sheepdog and Maltese, are at a high risk of eye irritation and infection.
Common causes of eye inflammation that can cause chronic trauma to your dog’s eyes and lead to pigmentary keratitis include:
- Entropion (eyelids rolling inwards) and ectropion (eyelids rolling outwards)
- Abnormal eyelashes
- Tumors of the eyelids
- Genetics
- Previous eye surgery
- Traumatic injury
- Autoimmune diseases
- Glaucoma
- Bacterial or fungal growth
- Nasal fold trichiasis
- Chronic corneal inflammation (pannus)
Pigmentary keratitis is also common in pups with dry eye syndrome, known as keratoconjunctivitis sicca (KCS). The lack of or minimal production of tears over the years can lead to chronic inflammation of the eye.
Chronic irritation may permanently alter the cornea’s immunity because the melanin granules often progress to cover the entire cornea surface if not addressed early enough.
Affected dogs will have abnormal blink reflexes (incomplete blinking) because of their inability to lubricate and protect the eye, causing chronic inflammation. Some pups will have a history of corneal surgeries or repeated corneal ulcers.
However, in some cases, no underlying cause can be linked to pigmentary keratitis, as some breeds are predisposed to it due to their genetic makeup.
Diagnosis Of Pigmentary Keratitis
Should you see any brown spot in one or both eyes, pay a visit to your vet so that they can investigate what’s causing it. The vet will want to know how the discoloration has progressed and if your pup shows signs of irritation, pain, or unusual behavior.
At times, there’s no outward sign to indicate the presence of pigmentary keratitis. But the ophthalmologist can discover the pigment while conducting a comprehensive routine examination. Here’s an overview of the extensive tests the vet will run on your dog’s eye:
1. Ophthalmologic Exam
The vet ophthalmologist will run a complete eye routine exam using an ophthalmoscope to inspect all parts of the eye. These include the cornea, conjunctiva, tear ducts, eyelids, retina, eye reflexes, and any abnormalities. Your vet will then conduct further diagnostic tests to rule out the exact cause of the pigmentation.
2. Schirmer Tear Test
The Schirmer test evaluates your pup’s tear production to rule out dry eye syndrome or KCS. A small paper test strip with a scale is placed between the eye and the eyelid to stimulate tear production. The tears are absorbed on the paper strip and show the level of tear production.
3. Fluorescein Dye
A yellow-green dye is used to differentiate pigmentation caused by corneal ulcers, abrasions, scratches, abnormal tear production, or foreign objects in the eye. The dye is placed onto the eye’s outer layer, and specific staining highlights issues with the cornea.
4. Tonometry
This test checks for glaucoma, a disease that causes abnormal pressure on the eye globe. A tonometer pen is attached to a plastic balloon that bounces on and off the eye surface to measure the intraocular pressure. If there’s a likelihood of infection, cultures can be sent to the lab to rule out the presence of bacteria or fungi.
5. Blood Diagnostics
Several underlying issues may cause light discoloration or dark brown eye spots. Blood screening checks the liver function, kidney function, hydration, hormone function, and electrolyte imbalance.
Is Pigmentary Keratitis In Dogs Painful?
Yes. There’s inflammation and pain which can cause discomfort to your dog. But with consistent treatment, your dog will recover from the disease and the accompanying pain.
Does Pigmentary Keratitis Cause Blindness?
Yes. If there’s no treatment for the underlying cause, your dog can become permanently blind. The infection progresses to the visual axis of your canine’s eyes. So, it would be best if you took measures to quickly treat this condition before it costs your dog its sight.
How Is Pigmentary Keratitis Treated in Dogs?
Based on the underlying cause, your vet will decide on the best treatment to prevent further pigment formation in the cornea. Here are the treatment options for pigmentary keratitis.
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Surgery
The ophthalmologist will recommend surgery if your dog’s pigmentation is caused by eyelid malformations such as entropion or ectropion. Your dog will undergo canthoplasty surgery to remove any long eyelashes embedded or growing incorrectly on the eyelids.
Surgery is often recommended for pups more likely to go blind in their lifetime and involves correcting nasal folds, dry eye syndrome, distichiae, and skin allergies.
Earlier, surgeries aimed at removing the pigmented section of the cornea, but this presented a high risk of complications such as scarring and infections. Furthermore, the procedure wasn’t a permanent solution because it only slowed down the deposition of the pigment.
There’s also the option of cryotherapy, keratectomy, or laser excision. But, like the other surgical procedures, they do not offer permanent treatment for pigmentation.
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Medication
Several medications are effective at treating the origin of corneal inflammation. Oral or applicable antifungal medications like voriconazole are appropriate for fungal infections. Similarly, antibacterial drugs are effective against bacterial infections. The treatment duration is between ten days and two weeks.
Suppose your dog’s pigmentary keratitis is caused by glaucoma. In that case, it will cause your dog’s eyes to bulge out due to inflammation. Consequently, the vet will recommend treatment to your dog for the rest of his life to regulate intraocular pressure.
Painkillers and topical antibiotics for five to seven days are effective against corneal ulcers. The ophthalmologist can also apply a soft contact lens on the eye to alleviate pain and protect the cornea.
But if your dog has multiple untreatable ulcers, he’ll have to undergo conjunctival grafts or a corneal transplant. For chronic inflammation resulting from autoimmune disease, the vet will administer an injection of corticosteroids and steroid eye drops.
Artificial tears boost the production of tears in dogs suffering from dry eye syndrome to prevent further irritation. You can also give your dog cyclosporine or tacrolimus to cure dry eye syndrome.
In summary, pigmentary keratitis is irreversible. The pigment can lighten over time but is unlikely to resolve fully. However, in cases of KCS, an appropriate tear film may help resolve the speckle completely. Over time the dark brown freckles may become paler and less noticeable.
Is Pigmentary Keratitis Permanent?
There’s no exact treatment for pigmentary keratitis in dogs except to treat the cause of this condition. With a proper diagnosis by the vet, your dog can recover quickly with the appropriate treatment.
More About Eye Melanoma In Dogs
Eye or ocular melanoma is a type of eye cancer that results from a disorganized and uncontrollable growth of melanocytes (melanin-producing cells). Melanocytic tumors can affect the eye in diverse ways, including:
- Uveal tumors
- Limbal melanocytoma
- Conjunctival and eyelid masses.
While most ocular tumors are benign, they can cause issues for the eye as they grow in size. In this article, we’ll focus on the two main types of eye melanoma: uveal Melanoma and limbal Melanoma.
Uveal Melanoma
This is the most common eye tumor in dogs. Uveal melanoma affects tissues of the uvea (choroid, iris, and ciliary body). Around 80% of uveal melanomas are non-cancerous (benign), and the rate of metastasis (growth and spread to other body parts) is less than 5%.
Limbal Melanoma
Limbal or peribulbar melanoma is less common in canines. The tumor develops from the proliferation of melanocytes at the sclera (white section of the eye) and limbus (border of the cornea). All limbal melanomas are benign.
What Does Melanoma Look Like In A Dog’s Eyes?
Ocular melanoma, whether malignant or benign, will affect the appearance of your canine’s eye. Iris melanoma will cause your dog’s iris to have one or more circular black or brown lesions. The spots may be elevated or flat; over time, they grow and congregate into pigmented masses. As for ciliary body melanoma, you’ll notice a dark mass protruding from the pupil.
As uveal tumors grow, they cause the pupil to dilate or distort its shape. This can trigger other signs, including:
- Uveitis (inflammation in the middle part of the eye)- the eyes become opaque
- Hyphema (intraocular bleeding in the mid-section of the eye)
- Glaucoma (elevated pressure in the eyeball)- the condition results in significant pain and leads to bulging eyes and eventually blindness. Signs of pain and discomfort include head shaking, squinting, lethargy, whining, slow movements, and placing paws on the head.
In contrast, limbal melanoma is distinguished by a different, elevated, dark brown mass spread between the limbus and sclera. The tumor typically invades the cornea leading to corneal inflammation, and the cornea becomes opaque or cloudy.
When the limbal melanoma grows outwards from the eye surface, it will cause conjunctivitis (inflammation of the eye surface) and excess tearing. Whether your dog has limbal or uveal melanoma, you’ll notice rubbing or scratching of the eye, which can cause corneal ulceration or eye infection. Symptoms include tearing, redness, squinting, and discharge.
What Causes Eye Melanoma?
The reason your dog may develop eye melanoma is not straightforward since very few cancers have a single cause. Most tumors are a complex combination of genetic, hereditary, environmental, and risk factors.
There’s evidence that ocular melanoma is caused by a genetic mutation in breeds with extensive skin pigmentation, such as Labrador Retrievers, Golden Retrievers, Schnauzers, German Shepherd dogs, and Cocker Spaniels.
The incidence of ocular melanoma is high in middle-aged to senior dogs across all breeds, including cross-breeds. The average age for diagnosis of eye melanoma is nine years, but in dogs like labradors with a higher genetic predisposition to eye melanoma, the period may be 1 to 2 years. There are no environmental factors linked to eye melanoma in dogs.
Diagnosis Of Eye Melanoma
Eye melanoma is diagnosed by evaluating the appearance of the tumor and the clinical signs. The ophthalmologist will perform a series of examinations, from a full physical exam to a complete eye assessment.
The assessment includes an examination of the internal components of the eye using an ophthalmoscope. The vet will also estimate the internal pressure using a tonometer. Other diagnostic procedures include x-rays and ultrasounds to determine the size of the tumor and the extent of spread to differentiate tumors from benign cysts.
As mentioned, 20% of uveal tumors are malignant (spread within the eye and other body parts). So, your dog will also undergo a process known as staging to determine the extent of growth and spread of the tumor. Staging involves a series of tests, including bloodwork, urinalysis, ultrasound or x-rays, and fine needle aspiration of neighboring lymph nodes.
How Does Eye Melanoma Progress In Dogs?
Eye melanoma can lead to abnormal eye structure and function and deteriorating eye health. Malignant uveal tumors will continue to grow but at a prolonged rate. Although rare, metastasis (spread) to the lungs and liver can occur.
If left untreated, benign uveal melanomas will expand to other intraocular structures invading the eye socket and rupturing the eye. Long-term consequences include uveitis, glaucoma, and impaired vision.
The growth rate is relatively slow for most limbal melanomas, but without treatment, it can invade the eye structures, including the cornea causing secondary keratitis. There is no evidence linking metastasis (spread) to limbal melanoma.
What Is The Treatment For Eye Melanoma?
The treatment of choice will vary for uveal and limbal melanoma.
Uveal Melanoma
Treatment for uveal melanoma will depend on the onset of the tumor, its progression, and the age and breed of your dog. The lesion is monitored periodically to determine if it will grow. If there’s growth, the mass can be removed with laser surgery or partial iridectomy (surgical removal of a portion of the iris) to retain the eye and vision.
If the lesion rapidly grows and spreads, the shape of the pupil is altered, or there is evidence of glaucoma, hyphema, or uveitis, enucleation (removal of the eye surgically) is recommended.
Enucleation is always advised in cases of invasive and fast-growing uveal melanomas. However, laser therapy may also be an alternative, but there’s no evidence suggesting chemotherapy is an effective treatment for eye melanomas.
Limbal Melanoma
Since limbal melanomas are benign and typically grow at a slow rate, they are monitored. Your dog will require surgery if the tumor invades other eye structures or grows aggressively. Surgery involves the removal of cancer and affected areas of the cornea or sclera.
Additional combination treatments may include radiation therapy, cryotherapy, or laser therapy. 30% of limbal melanomas in dogs will regrow and require further treatment. Enucleation is recommended in severe cases where the tumor penetrates the eye, causing blindness.
How Long Can A Dog Live With Eye Melanoma?
Most eye melanomas are non-cancerous (benign) and will not spread to other body organs. For malignant melanomas, your dog can live for about 5 to 8 months post-diagnosis and up to 36 months following surgery.
Malignant melanoma is complicated with very minimal chances of survival, even with surgery, because of the development of life-limiting metastatic disease affecting the lungs and lymph nodes.
What More Information Do I Need?
It’s heartbreaking for dog owners to consider enucleation (removal of the eye) even with a diagnosis like melanoma. But it can provide relief for tumor-related pain and save Fido’s life.
The good thing is most dogs adjust well to the change in vision. Benign tumors have minimal risk of metastasis, so there is a high chance your dog will recover and live a happy and healthy life with the correct treatment.
In Conclusion
Your dog’s eyes are the most complex and precious organs, and maintaining healthy eye function is key to a longer and happier life. You must check your dog’s eyes regularly and take them to the vet when you notice any changes, no matter how minor.
The distinct brown spot in your dog’s eyes could result from natural pigmentation common to specific breeds or old age. Alternatively, it can be caused by pigmentary keratitis or eye melanoma.
Pigmentary keratitis is relatively harmless unless the spot expands onto other structures of the eyes. On the other hand, melanoma is fatal with a high fatality rate and can cost your dog his eyes and even his life.
Most canine eye diseases are “silent,” but understanding the eye anatomy and signs and symptoms to look out for can help keep your Fido’s eyes healthy.