When dogs develop hyperpigmentation, certain parts of their skin sometimes get conspicuously darker. The condition isn't limited to just the skin in canines, however. Some dogs experience hyperpigmentation of their cornea, which is part of their eyes. Corneal hyperpigmentation is often a symptom of keratoconjunctivitis sicca.
If your dog's eyes appear to have an unusual dark haze over them, then it might be due to corneal hyperpigmentation. Corneas are the clear outer surface layer of the eyes that cover the iris, anterior chamber and pupil. You might have to go right up to your pet's eyes to notice the darkness. Hyperpigmentation is often a result of the scarring of the corneas.
Little Blood Vessels
While hyperpigmentation of the corneas often gives the impression of overall darkness to the eyes, a careful look can sometimes reveal more. The presence of little blood vessels all over your pooch's corneas is a condition called neovascularization.
When corneal scarring and pigmentation are significant, it can affect your dog's eyesight. If your dog is giving off any clues of vision problems, scarring may be the culprit. Some typical signs of the deterioration of eyesight in canines include bewilderment in unfamiliar locales, squinting, hesitation about moving around and problems locating food dishes. If it's not difficult to alarm your pet, that could indicate troubles with eyesight, as well.
Hyperpigmentation and Keratoconjunctivitis Sicca
Corneal hyperpigmentation in dogs is a symptom of a condition known as keratoconjunctivitis sicca, or dry eye. When dogs develop dry eye, their tears contain inadequate levels of water. Apart from corneal hyperpigmentation, some telltale symptoms of the ailment include excessive blinking, eye discharge and redness and soreness of the eyes. Keratoconjunctivitis sicca frequently appears in canines of the pug breed, according to Brenda Belmonte, author of "The Pug Handbook." Boston terriers, Lhasa apsos, English springer spaniels, American cocker spaniels, Yorkshire terriers and English bulldogs are other breeds vulnerable to the condition, as well. Don't ignore the emergence of brown layering over your dog's corneas. If you observe any irregularities with your dog's eyes in general, take him to the veterinarian immediately for a thorough examination.
- Newport Harbor Animal Hospital: Goopy Eyes Caused by Dry Eye - Dogs
- MSD Animal Health: What's Your Diagnosis?
- Manual of Small Animal Emergency and Critical Care Medicine; Douglass K. Macintire, Kenneth J. Drobatz and Steven C. Haskins, et al.
- Animal Hospital of Montgomery: Dry Eyes in Dogs
- The Pug Handbook; Brenda Belmonte
- ASPCA: Blindness
- PetMD: Dry Eye Syndrome in Dogs
- Chris Amaral/Digital Vision/Getty Images