Causes of Dry Eye in Dogs

Dry eye, or Keratoconjunctivitis Sicca (KCS), is a common condition where the dog’s eyes stop producing an adequate amount of tears to keep the eyes moist. The lack of moisture, if allowed to continue for a prolonged period, can cause additional problems with the eye, potentially causing a loss of vision.

Causes of Dry Eye

When a dog has KCS, in the majority of cases, both eyes are affected and can be brought on by one of several causes.

• The most common cause of KCS is an immune disorder that destroys the tear ducts and reduces the production of the watery part of the tear film. This reduction of moisture opens the path to infection and other disorders caused by the lack of protective moisture for the eyes.
• Sulfonamides are an antibacterial agent often used in the treatment of bacterial infections. These drugs can cause a temporary reduction in tear production. Once the medication is discontinued, tear production should return to normal after a period of time.
• Several anesthetics can also cause a temporary reduction of tear production. Tear production can be reduced almost 100% by anesthetics. Once the anesthetic is out of the dog’s system, tear production should return after a period of time.
• If your dog is suffering from chronic viral or bacterial conjunctivitis, KCS is a secondary problem to watch for. The mucous produced by the eye can cause progressive drying of the eye’s surface, again causing additional problems.
• Trauma or injury to the facial nerves can also cause a reduction in tear production.
• The viral infection of Canine distemper can also destroy the mechanism that produces tears in a dog’s eyes.

Problems Caused by KCS

Chronic Dry Eye, if left untreated, can bring on a condition called pigmentary keratitis. The KCS causes a thickening of the surface of cornea, eventually causing the pigmentary keratitis. This condition creates a darkening of the surface of the eye, eventually leading to blindness.

Diagnosis of Dry Eye

The symptoms of dry eye include mucous discharge, inflammation of the cornea and mucous membranes and pain. Your dog will most likely paw at his eyes in an attempt to relieve the pain and discomfort he’s experiencing. If your veterinarian suspects KCS, he will most likely conduct a Shirmer tear test to see if there is adequate tear production and will examine the mucous production of the eye. Often a veterinarian will refer you to a veterinary ophthalmologist if he thinks a specialist is required for effective treatment.

Treatment of KCS

Treatment of KCS can consist of eyedrops or may even require surgery. The surgical procedure, while effective, typically does not cure the problem completely and will require the dog to have eyedrops for the balance of his life. Eyedrops prescribed include artificial tears, cyclosporine to stimulate natural tear production, antibiotics drops, mucolytics to decrease mucous production and hormones.

While some breeds, such as Shih Tzus, American Cocker Spaniels, Pugs and Pekingese are more prone to dry eye, other breeds can be afflicted with this disorder as well. While there are several things that can cause KCS, the actual cause is often unknown and treatment proceeds in order to provide the dog relief from an uncomfortable condition of the eye.