This Common Eye Condition Can Lead to Blindness

by Dr. Becker

Dry eye syndrome is very common in dogs, less common in other species, and goes by the tongue-twisting scientific name, keratoconjunctivitis sicca (KCS). "Kerato" refers to the cornea of the eye, "conjunctivae" are the pink membranes in the eye socket, "itis" means inflammation, and "sicca" means dry.

If your dog has KCS, it means she has a dry, inflamed cornea and conjunctiva resulting from a lack of water in the tear film over the eyeball and in the lid lining. Normal tear production provides your dog’s eyes with lubrication and anti-bacterial agents and flushes away irritants and infectious agents. Tears are produced by two lacrimal glands in each eye — one just above the eye and the other in the third eyelid.

Dry eye is a condition in which the tear mixture, which consists of oil, mucus and mostly water, is absent the water. Only oil and mucus are being 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.

Why Dogs Develop Dry Eye

The most common cause of KCS in dogs is immune-mediated inflammation and tissue destruction in tear-producing glands, a problem often seen in Cocker Spaniels, Miniature Schnauzers, and West Highland White Terriers.

Brachycephalic breeds (breeds with short muzzles and bulging eyes), such as the Cavalier King Charles Spaniel, English Bulldog, Lhasa Apso, Pug and Shih Tzu are also predisposed to KCS. Additional causes of dry eye include:

Congenital disease, such as small or absent lacrimal glands Radiation therapy near the eye
Infectious disease, such as canine distemper virus Trauma to the head
Neurologic deficiency, such as loss of nerve innervation to the eye Exposure to certain antibiotics and anesthesia, as well as sulfa derivative medications
Endocrine disease, including hypothyroidism, Cushing's disease, and diabetes mellitus Prolapsed gland of the third eyelid ("cherry eye") and/or removal of the gland of the third eyelid*
*Removal of the third eyelid lacrimal gland sometimes occurs during surgery for cherry eye. If your dog has cherry eye, which is what we call it when the lacrimal gland pops out, I recommend asking your veterinarian to surgically replace the gland rather than simply cutting it out. If the gland is removed, your dog won’t be able to produce tears for the remainder of his or her lifetime.

Diagnosing KCS

Dogs with KCS often present to veterinarians with painful, red eyes and a thick yellow discharge. Advanced KCS is obvious just by looking, but early on, it can resemble a simple case of conjunctivitis.

The condition most often involves both eyes and can cause secondary corneal ulceration or bacterial conjunctivitis. Corneal ulceration with a secondary infection can lead to loss of an eye. Chronic, uncontrolled dry eye may also lead to corneal pigmentation, vascularization, and scarring, which may lead to visual impairment.

Several diagnostic tests are used to diagnose KCS, the most important of which involves looking at the corneal surface cells and tear film with a biomicroscope. Paper test strips called Schirmer Tear Test strips may also be used to measure tear production from each eye. The tear test is performed by placing a strip of special paper just inside the lower eyelid in the outer corner of the eye.

The paper is left in place for 60 seconds to allow the moisture in the eye to wet it. At the end of a minute, the length of the moistened area on the paper is measured. A length of 15mm or more is normal. A length 11 to 14mm is borderline. A length of less than 10mm is dry, and a length of less than 5mm is severely dry.

If your dog has a normal tear quantity but has clinical signs of KCS, your veterinarian or veterinary ophthalmologist may also perform a tear film break-up time test to confirm the diagnosis.

As I noted earlier, dogs with dry eye are predisposed to corneal ulcers, so your vet may also use a fluorescein stain to check the eyes for abrasions or ulcerations. A sample of aqueous fluid may be taken for a culture and sensitivity test to measure the bacterial growth in the eye and whether there may be an underlying infection as well.

How Dry Eye Is Treated

Treatment of dry eye syndrome typically involves topical medications like artificial tears and lubricants that will be necessary in most cases for the rest of your dog’s life. These medications work to reduce inflammation and stimulate natural tear production and are usually administered two to three times a day.

If an underlying disease, allergy or infection is identified as the cause of your dog’s KCS, it will also need to be treated. Any corneal ulcers will need to be treated as well until they are completely healed.

Depending on the root cause of the lack of tear production, certain prescription eyedrops will be given. If there’s an underlying autoimmune disorder, tacrolimus or cyclosporine eyedrops are beneficial for reducing the immune-mediated destruction of the tear gland.

Most dogs with dry eye respond well to consistent, as-prescribed use of topical medications. For those who don’t, a surgical procedure called a parotid duct transposition may be recommended. The procedure involves redirecting the parotid salivary duct from the mouth to the eye to provide salivary secretions to the cornea.

A parotid duct transposition is a highly complex procedure requiring a great deal of post-surgical maintenance for the remainder of the dog’s life. It should be performed only by a board-certified veterinary ophthalmologist. Fortunately, the procedure is performed infrequently these days thanks to the development of more effective eyedrops.

Regular rechecking of tear glands using the Schirmer test is important in all cases of dry eye, because that’s how we determine whether the condition is improving or getting worse.

Additional Suggestions for Managing Dry Eye in Your Dog

It’s very important to keep your dog’s eyes clean and free of discharge, and you also want to clean the eyes before applying medication to prevent secondary infections.

There are homeopathics and Chinese herbs that can be given orally that can be beneficial in improving tear production, but my favorite oral supplement for KCS is maqui berry, which research demonstrates improves tear production in animals.2 I find it works exceptionally well to help restore natural tear production if instituted early the disease state.

Many dogs with KCS have progressively less tear production over time, which means you’ll need to supply tears topically. The less tear production your pet has, the more responsibility you must assume for lubricating the eyes. Dogs with very poor tear production will need their eyes lubricated many times each day, but it’s really the only way to keep your pet feeling comfortable.

Never use Visine or any over-the-counter human medicated eyedrops for eye irritation in pets. There are a few natural tear products for humans, both drops and gels, which your veterinarian may recommend, but never assume a human eye product is safe for your dog without consulting your vet first.

Animals with KCS are highly susceptible to corneal ulceration and other eye injuries, so it’s important to watch for signs of pain so you can get your dog to the vet before serious injury to the eye occurs.

If it seems your dog is constantly producing eye debris, or if as soon as you clean your pet’s eyes you need to clean them again, or if your pet is continually pawing at his face or rubbing his head up and down the couch or the carpet because his eyes are irritated, make an appointment with your veterinarian for a Shirmer tear test to check for dry eye.

The sooner you identify a lack of adequate tear production, the sooner you can begin a treatment protocol to help improve your dog’s eye health. Integrative practitioners have additional "tools" in their tool bag (including maqui berry) to improve tear production in mild to moderate cases of dry eye. And these modalities can be combined with prescription eyedrops to slow the progression of disease in many cases.

Because many cases of KCS are immune-mediated, my recommendation is to begin titering after one or two well-timed puppy vaccines and insist on titers throughout your dog’s life (instead of unnecessary additional vaccines), once protective immunity has been established.