What is Pigmentary Keratitis in Dogs?

Pigmentary Keratitis

Pigmentary keratitis in dogs is a brown-to-black discoloration of the cornea. The discoloration is caused by the deposition of the pigment melanin and is triggered by chronic irritation.

Pigmentary keratitis is also known as pigmentary keratopathy or corneal melanosis. According to the Clinical Atlas of Canine and Feline Ophthalmic Disease, pigmentary keratitis is fairly common in certain breeds.

As Dr. Katie Comerford explains, “Pigmentary keratitis is commonly seen in certain breeds of dogs, especially those with very short noses and large eyes (brachycephalic breeds). While the discoloration itself is not necessarily a problem, its presence in your dog’s eye is always a red flag that there is something abnormal happening with the eyes that needs to be investigated.”

What does Pigmentary Keratitis in Dogs Look Like?

Pigmentary keratitis looks like brownish-to-black discoloration on the surface of the eye. The pigment deposits can be localized or scattered. The pigmentation varies from faint brown speckles to a dense black patch that obscures vision.

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Is Pigmentary Keratitis in Dogs Painful?

Yes, pigmentary keratitis is painful.

To be more accurate, the melanin deposition itself is not painful, but most underlying causes are. For example, it is often associated with chronic inflammation, which is painful. It is also associated with vascularization and scarring, which impair vision.

Does Pigmentary Keratitis Cause Blindness?

Yes, pigmentary keratitis can cause blindness. In some cases, as mentioned previously, a dense black patch will obscure vision altogether, which leads to blindness.

Therapy will increase the chance of saving your dog’s vision. Management of this corneal disease is crucial, and proper diagnostic tests are required to increase the chance of saving your dog’s vision.

What Causes Pigmentary Keratitis in Dogs?

Pigmentary Keratitis: What You Need to Know

Pigment usually deposits into the cornea due to chronic irritation. Here are some common causes of corneal melanosis in dogs.

  • Abnormal Eyelashes: Misdirected growth of eyelashes, such as trichiasis and distichiasis, can result in pigment deposition.
  • Nasal Fold Trichiasis: Due to abnormal facial features, in brachycephalic breeds, the hair on the nasal fold can irritate the eye surface, causing ocular conditions.
  • Eyelid Abnormalities: Problems with the eyelids are another potential cause. This includes issues like entropion (inward-rolled eyelids) and ectropion (outward-rolled eyelids).
  • Keratoconjunctivitis Sicca (KCS): Dry eye in dogs due to inadequate tear production or distribution of the tears can cause pigmentary keratitis.
  • Chronic Superficial Keratitis (Pannus): This immune-mediated condition occurs in breeds such as Belgian Tervurens and German Shepherds and causes dark eye pigmentation.
  • Glaucoma: The prolonged increases of pressure within the eye result in enlargement of the eyeball and cause chronic irritation. 
  • Corneal Ulceration: Dog eye ulcers are typically due to eye injuries. Chronic issues develop if the eye isn’t treated immediately. Dark pigment may also occur after an ulcer heals.

Since pigmentary keratitis is more common in brachycephalic breeds, we can say that breed is a risk factor, and this form of abnormal pigment deposition may have a genetic component.

What Are the Signs & Symptoms of Pigmentary Keratitis in Dogs?

The darkening of the ocular surface is the most prominent clinical sign. Here is a closer look at the signs and symptoms of pigmentary keratitis in dogs.

  • Conjunctival Redness: As in any other case of eye irritation, the conjunctiva will be red and inflamed.
  • Tearing or Dry Cornea: Depending on the underlying cause, the eye can be covered with a thick tear film or dry.
  • Eye Discharge: More often than not, the eye will be covered with discharge. The exact type of discharge depends on the underlying eye condition.
  • Vascularization: The white of the eye is bloodshot – the blood vessels in the eye are large and swollen.

How is Pigmentary Keratitis in Dogs Diagnosed?

To diagnose corneal melanosis, the vet will perform an ophthalmic examination. If necessary, the vet may refer you to a board-certified veterinary ophthalmologist.

First, the vet will use a lighted ophthalmoscope to inspect the surface of the cornea – this will help visualize the increased pigmentation. Then, they will perform various tests to determine the cause.

For example, fluorescein staining for corneal ulcers, Schirmer tear test for dry eye, tonometry for glaucoma, and cultures for bacterial and fungal eye infections.

What is the Treatment for Pigmentary Keratitis in Dogs?

Pigmentary Keratitis: What You Need to Know

The first priority is to correct any of the underlying issues. There technically isn’t any treatment for pigmentary keratitis. Your vet will identify the underlying cause to treat and heal the cornea. 

In veterinary ophthalmology, there are many treatment options. Generally speaking, we can divide them into two groups – medical and surgical treatments.

  • Medication: If the underlying cause is an infection or dry eyes, the vet will suggest eye drops for dogs. Antibiotics, corticosteroids, cyclosporine, and tacrolimus are some of the ingredients in the drops. They are often combined with lubricants and artificial tears to increase tear production.
  • Surgery: If the cause of pigmentary keratitis is something like entropion or ectropion, the vet will perform a surgical correction to the defect.

We should note that even if the underlying cause is managed, the pigment rarely disappears. It can become thinner over time, but not always.

There is a surgical procedure called keratectomy that removes the pigment, but it is risky and rarely performed.

Does Pigmentary Keratitis in Dogs Spread?

Yes, the pigmentation can spread.

According to Ophthalmology for Animals, pigment migration is possible, “Chronic irritation may permanently alter corneal immunity as well because the pigment migration often progresses to areas of the non-irritated cornea if the problem is not addressed.”

What Happens If Pigmentary Keratitis in Dogs is Left Untreated?

There is no known cure for the condition except for treating the inflammation’s cause. It can often be managed successfully with veterinary care.

But if pet owners don’t take their dogs to the veterinarian for an exam and ignore the signs, and the underlying cause is left untreated, pigmentary keratitis can lead to blindness.

How to Prevent Pigmentary Keratitis in Dogs?

The best way of preventing pigmentary keratitis is to take care of the dog’s eyes and, in case of an eye condition, seek immediate veterinary attention. While corneal melanosis is not preventable, the underlying causes and lesions are.

Therefore, keep your dog’s eyes clean – you can use dog eye wipes or eye wash for dogs. If you notice something unusual, take your dog to the vet. Eye conditions progress quickly and can go from bad to worse really quickly.