KCS: Dry Eye Syndrome in Dogs

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KCS (keratoconjunctivitis sicca), also known as dry eye syndrome, is a fairly common eye condition in dogs that can be quite uncomfortable. If it is left untreated, KCS can negatively affect eyesight and even cause permanent eye damage and blindness.

What Is Canine KCS?

KCS occurs when there is a disruption in tear production. In dogs, two glands in the eyes are responsible for producing tears: the lacrimal gland at the top of the eye and the gland of the third eyelid at the bottom of the eye.

A dog's tears are made up of three layers: oil, water, and mucous. KCS occurs when production of the water layer is malfunctioning.

A lack of tears in the eye results in changes to the cornea, including darkening and thickening. The eye can be more easily injured by foreign debris, which isn't washed out normally. The delicate tissues of the eye, which require moisture to stay healthy, will eventually become injured and not function properly.

KCS is uncomfortable or painful for the dog.

Signs of KCS in Dogs

Dogs suffering from KCS will usually show some or all of the following signs, depending on how long the disease has been present and how severe it is:

• Ropey, yellow discharge from the affected eye(s).
• Dark discoloration of parts of or the entire cornea of one or both eyes.
• Redness in the whites of the eye(s).
• Squinting.
• Swiping at the eyes with paws or rubbing them on objects.

Causes of Canine Dry Eye Syndrome

KCS in dogs can be caused by several conditions, including:

• Autoimmune destruction of the tear-producing tissue of the eye.
• Canine distemper virus.
• Congenital under-development of tear-making tissue in the eye.
• The use of certain medications, such as the sulfa family of antibiotics.
• Trauma to the eye, resulting in damage to the tear-producing tissues.
• Surgical damage to or removal of the gland of the third eyelid to correct prolapse, also known as "cherry eye."

Dog Breeds Commonly Affected by Dry Eye

Certain breeds are more commonly affected by autoimmune-mediated KCS than others. These include Cocker spaniels, miniature Schnauzers, pugs, and West Highland white terriers.

Yorkshire terriers are more commonly affected by a congenital under-development of tear gland tissue than other dog breeds.

Diagnosis of KCS in Dogs

A Schirmer Tear Test (STT) is done when KCS is suspected in dogs or when a veterinarian wishes to rule KCS out when a dog presents with redness of the eyes.

During a Schirmer Tear Test, a special strip of paper is placed just under the dog's lower eyelid for 60 seconds. The strip will measure the dog's tear production, and the doctor will be able to see if it is too low.

Treatment of Dry Eye Syndrome in Dogs

Treatment of canine KCS may include the following medications:

• Cyclosporine or tacrolimus eye drops or ointment. These medications decrease the immune system's destruction of the eye's tear gland tissue.
• Antibiotic drops or ointment. Secondary eye infections are common in dogs with KCS and may need to be treated with topical antibiotics.
• Steroid drops or ointment. The inflammation and redness in the eyes of a dog with dry eye syndrome may be treated with topical steroids during the early phase of treatment.
• Artificial tear drops or ointment. These can help provide extra lubricant for the eyes, make them feel better, and decrease the cornea's negative reaction to the lack of natural tears.

Your veterinarian will wish to recheck your dog periodically during treatment for KCS, to evaluate his response to medications and adjust them as necessary.

You can read an overview of other ocular diseases in dogs here: "Common Eye Conditions in Dogs."

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