10 reasons to closely observe your dog's eyes

Analysis by Dr. Karen Shaw Becker

canine eye conditions

Story at-a-glance -

  • Since there are a number of eye diseases that occur in dogs, it’s a good idea to monitor the appearance of your pet’s eyes and possible changes in her vision
  • Two common conditions that can affect the eyelids are entropion, in which the lower eyelid turns inward, and ectropion, where the lower eyelid droops or folds outward
  • Cataracts cause the eyes to take on a bluish appearance, but so does nuclear sclerosis, a harmless change that occurs in dogs’ eyes as they age
  • Any change in your dog’s eyes or vision require a visit to your veterinarian as soon as possible for diagnosis and treatment, if necessary

Unlike many humans, dogs don’t get yearly eye exams. Board-certified veterinary ophthalmologists typically see only patients with suspected or diagnosed diseases of the eye, and “veterinary optometrist” isn’t a thing (probably because animal companions don’t wear glasses or contact lenses!).

As a result, most dog parents don’t give much thought to the health of their pet’s eyes unless or until something goes wrong, and believe it or not, there are many things that can go wrong with dogs’ eyes and their ability to see. In fact, in a recent list of common conditions that plague dogs, nine of the top 26 involved diseases of the eye.1

Common canine eye conditions

1. Entropion — Entropion is a condition in which a portion of a dog’s eyelid is inverted, meaning it’s folded or rolled inward. This can cause eyelashes or other hair to rub against the surface of the eye, causing irritation and pain. If the rubbing causes scratches on the surface of the eye, it can lead to corneal ulceration or perforation. It can also cause scar tissue to grow over the injury in a condition known as pigmentary keratitis.

A dog with entropion will typically squint and have an excessive amount of discharge from the affected eye. Sometimes there can be sensitivity to light and pawing at the eyes, especially when the dog is outside. Other signs include inner eye inflammation, an eye tic or sagging skin around the eye socket.

Some cases of entropion are never more than a minor annoyance, while more severe cases can cause significant pain, eye ulceration, scarring and ultimately, loss of vision.

2. Ectropion — This condition is more-or-less the reverse of entropion in that the lower eyelid droops or rolls out from the surface of the eye. The most common sign of ectropion is a distinctly droopy lower eyelid. Affected dogs also tend to have watery eyes, swollen or red conjunctiva, tear staining, inflammation and/or eye infections.

Signs of ectropion often seem to improve, then recur at a later date. In severe cases, symptoms don’t improve and won’t, without treatment.

3. Keratoconjunctivitis sicca (KCS) or dry eye — Dry eye is a condition in which the tear mixture, which consists of oil, mucus and mostly water, is absent. Only oil and mucus are secreted, which is why dogs with KCS have thick, yellow discharge from their eyes. The eyes get red and the cornea, in time, turns brown. If the condition isn't treated, blindness can result.

4. Cataracts — Cataracts form a blue cloud of varying degrees inside the capsule that houses the lens of the eye. Cataracts can progress very slowly over many years or they can come on very quickly, leading to blindness within a few days or weeks.

Cataracts in dogs are often inherited. They can also be caused by diabetes, toxicity from drugs and pest preventives, another underlying eye disease, trauma to the eye, nutritional deficiencies in puppies and as part of the aging process. In an older dog, it’s important to distinguish cataracts from another eye condition that causes a cloudy, bluish-grey appearance called nuclear sclerosis, which is considered a normal part of aging.

If your dog is diagnosed with cataracts, less troublesome ones will be rechecked periodically to see if they're progressing. Sometimes anti-inflammatory eye drops are prescribed. But if your pet's vision is affected, her quality of life is compromised or the cataracts are progressing rapidly, surgery is sometimes recommended to restore vision.

5. Progressive retinal atrophy (PRA) — PRA is an inherited disease that results in loss of eyesight over a period of months to years. PRA is most often seen in Cocker Spaniels, Border Collies, Irish Setters, Norwegian Elkhounds, Schnauzers and Poodles.

The retina, which is in the back of the eye, is composed of rods that perceive light and cones that perceive color. Normally the rods and cones mature by the time an animal reaches about 12 weeks of age, but in some pets with PRA, they never completely mature and may begin to degenerate at an early age.

6. Cherry eye The medical term for this condition is prolapse of the third eyelid gland. Dogs have a membrane in the corner of each eye, located underneath the lower lid, which houses a tear gland. When this gland is healthy it's not visible. But occasionally it will pop or bulge out and you'll see red, thickened, irritated-looking tissue inside the corner of the eye.

Once this gland pops out, it can become increasingly inflamed and even develop an infection. Fortunately, cherry eye isn't typically painful for dogs. However, because the gland is no longer seated in its normal position, it can prevent adequate lubrication of the eye.

7. Trichiasis — Trichiasis is common in brachycephalic breeds with flat noses and prominent eyes, such as the Pekingese, Pug and bulldog, as well as breeds with long hair around their eyes, such as the Cocker Spaniel. Trichiasis can cause squinting or blinking of the eyes, excessive tearing, eyelid twitching, swelling, blood vessel invasion of the cornea and pigmentation of the iris (the colored portion of the eye).

8. Corneal ulcer — Corneal ulcers are wounds to the cornea usually caused by an abrasion, scratch, puncture or other trauma to the eye. Less common causes include a foreign body in the eye, a chemical burn, infection, lack of adequate tears, inability to completely close the eyelids, entropion, disease and facial nerve paralysis.

A corneal ulcer can involve one layer up to all four layers. A mild or superficial ulcer involves just the epithelium. Ulcers are considered severe or deep when they also impact the middle and innermost layers of the cornea. These ulcers, sometimes called ulcerative keratitis, are a common eye injury in dogs. They can cause a great deal of irritation and discomfort for your pet.

9. Lens luxation — In some dogs, the supportive ligaments of the lens weaken or tear, which causes the lens to dislocate from its normal position. Weakness of the lens ligaments is known to be hereditary in terriers, the Chinese Shar Pei and the Border Collie.

A dislocated lens can fall backward into the eye (posterior luxation), which is typically painless. Alternatively, the lens can fall forward into the eye (anterior luxation), where it blocks drainage of fluid and can result in glaucoma or increased intraocular pressure (IOP), which is extremely painful and can cause permanent blindness.

10. Glaucoma — In dogs, glaucoma is either primary or secondary. Primary glaucoma is inherited and occurs in many breeds, including the Cocker Spaniel, Basset Hound, Chow, Jack Russell, Shih Tzu and the Siberian Husky. Primary glaucoma typically starts in one eye and eventually involves both eyes.

Secondary glaucoma occurs when other eye diseases are present that inhibit drainage of the aqueous humor inside the eye. These diseases include inflammation of the eye (uveitis), advanced cataracts, cancer of the eye, lens displacement and chronic retinal detachment.

The increasing pressure inside the eye from glaucoma causes pain. The pressure can get much higher in dogs than it does in humans, so we can assume the condition is more painful for dogs than it is for you or me. The pain of glaucoma is most likely felt as a severe headache.

Loss of vision is another symptom and often that is what brings pet owners to the vet. Unfortunately, permanent blindness can occur within a matter of hours, in cases of rapidly developing glaucoma where the pressure inside the eye becomes very high, very quickly.

Needless to say, any noticeable changes in your dog’s eyes or her ability to see should prompt a phone call to your veterinarian. Your pet’s eyes should be examined as soon as possible to determine exactly what’s going on, and whether treatment is needed.

+ Sources and References