By Leslie Manis, Health/Genetics Chairman, ASTC
[Every effort has been made to ensure accuracy of information. However,
this is not a substitute for prompt veterinary care. Any similarity
to other publications is unintentional. Published
online at Sealyhealthguard.org, 8/1/11. Originally
published in ASTC The Barks 2002]
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Dry eye, or keratoconjunctivitis sicca, describes the changes
in the eye which result from lack of tear production.
In humans, it can be associated with rheumatoid arthritis, diabetes,
Sjogren's syndrome (dry eyes, dry mouth and lupus), thyroiditis, rosacea
menopause and aging. Tear volume decreases as much as 60 percent by
age 65 from the volume at age 18. Dry eye affects 75 percent of people
In dogs, it can also be age-related and can also be caused by certain
drugs (like sulfas), chronic untreated conjunctivitis, viral infections,
hypothyroidism or trauma. It can also be an autoimmune disease, in
which the tear glands ant recognized as foreign and are destroyed
by the body. Some breeds are predisposed to dry eye, including miniature
schnauzers, cocker spaniels, beagles, basset hounds, West Highland
White Terriers, Yorkshire terriers and bulldogs.
George Padgett, DVM lists dry eye as a genetic disease of the Sealyham
Terrier in his book Control of Canine Genetic Diseases.
Symptoms of dry eye include chronic mucus or pus discharge, conjunctivitis,
squinting, crust around the eyes, rubbing of the eyes and inflammation
of the cornea. Frequent eye infections can occur due to the lack of
tears. In a normal eye, oxygen and nourishment are supplied to the
cornea (clear portion at the front of the eye) by a three-layered
tear film. There is no blood supply in the cornea. The outermost layer
of the tear film is an oily layer supplied by glands in the eyelids.
This layer helps prevent evaporation of the next layer.
The middle layer is the watery layer produced by the main tear gland
and a gland in the third eyelid. This is the layer where the decrease
in tear production takes place. The innermost layer, in direct contact
with the cornea, is mucus produced by glands located in the folds
of the eyelid. This helps the liquid layer remain attached to the
A breakdown of the tear film by a decrease in production of the water
layer causes dry eye. This results in dryness to areas of the corneal
surface and in advanced cases, drying of the entire corneal surface.
The cornea is deprived of nourishment and oxygen and rapidly undergoes
These changes result in brown pigmentation, scar tissue growth, blood
vessel growth and even ulcer development. This can lead to partial
or total vision loss. It is a common cause of canine blindness.
The eyes of a dog with dry eye sting constantly; the dog is uncomfortable
almost all the time. Because of a lack of the watery layer of the
tears, the oil and mucous layer production is increased. This leads
to a thick, gunky, greenish discharge that sticks to the hairs around
the eye. Often this is the main reason the owner takes the dog to
the veterinarian. The discharge will clear up when medication is used
frequently enough but will return when the drug is stopped.
Treatments in the past have included topical anti-inflammatory drugs
and cortisone when there is no ulceration, antibiotics and artificial
Pilocarpine is a drug which stimulates the tear gland, but also may
stimulate glands all over the body. In December 2002 the FDA approved
the human drug Restasis for chronic dry eye. This drug is based on
University of Georgia research conducted by veterinary ophthalmologist
Renee Kaswan, a former professor at the UGA College of Veterinary
Medicine. This drug reduces the inflammation of the tear ducts and
enables them to result their normal functions.
Many previous treatments were basically wetting agents. This drug
allows tear glands to regenerate and decreases inflammation in the
cornea, conjunctiva and eyelids, further relieving the signs and symptoms
of dry eye.
More than a decade ago, Kaswan began developing and implementing
a treatment for dry eye. She found that ultra-low doses of cyclosporine,
a drug used in organ transplant patients to suppress the body's rejection
response, are an effective treatment for canine dry eye. Her research
netted her the University's Inventor of the Year Award in 1998 and
its Creative Research Medal in 1992. Her canine drug invention, Optimmune,
was the first of its kind and was approved for use in dogs in 1994.
The late University mascot, UGA IV was among the first canines to
benefit from the treatment.
Cyclosporine, which is referred to as a "major breakthrough" on
the CERF website, is about 75 percent effective in stimulating new
tears in the dog. It has to be used absolutely as directed. If you
skip a dose or run out of the medication, the dry eye symptoms will
immediately recur. In addition, it is crucial that you have your dog
checked as directed to monitor treatment success.