By Dr. Karen Shaw Becker
If you’re like most dog parents, you probably don't give much thought to the health of your pet’s peepers, but there are actually an astonishing number of things that can go wrong with your canine companion’s eyes and his ability to see, including the following conditions.
10 Common Eye Conditions in Dogs
1. 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 when you look at your dog.
But occasionally this gland will pop or bulge out and you'll see red, thickened, irritated-looking tissue inside the corner of your pup's eye. And 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.
2. Corneal ulcer. Corneal ulcers are wounds to the cornea usually caused by an abrasion, scratch, puncture or other trauma to the eye. Other causes can include a foreign body in the eye, a chemical burn, infection, lack of adequate tears, inability to completely close the eyelids, entropion (where the eyelid folds inward), disease and facial nerve paralysis.
These ulcers, sometimes called ulcerative keratitis, are a common eye injury in dogs (and cats). They can cause a great deal of irritation and discomfort for your pet. 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.
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 being secreted, which is why pets 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. 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.
5. 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.
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.
6. Entropion. 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 of entropion include inner eye inflammation (which is called keratitis), an eye tic, a sagging of the skin around the eye socket or in worst-case scenarios, a rupture of the cornea. 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.
7. Ectropion. 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 typically do not wax and wane and will not improve without treatment.
8. Lens luxation. In some dogs, the supportive ligaments of the lens weaken or tear, which causes the lens to dislocate from its normal position. It 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 intra-ocular pressure (IOP), which is extremely painful and can cause permanent blindness. Weakness of the lens ligaments is known to be hereditary in terriers, the Chinese Shar Pei and the Border Collie.
9. Progressive retinal atrophy (PRA). PRA is an inherited disease that causes dogs to lose their 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.
10. Distichiasis. Excessive eyelash hairs growing from the dog's eyelids rub against the cornea, irritating it. The affected eye becomes red, inflamed and may develop a discharge. Dogs with the condition typically squint or blink a lot and tend to rub their eyes against objects such as furniture or carpet. In severe cases, the cornea can ulcerate and appear bluish in color.
If you notice any changes in your dog's eyes or her ability to see, you should make an appointment with your veterinarian. I recommend you have your canine companion's eyes examined as soon as possible to determine exactly what's going on, and whether treatment is needed.