Keratoconjunctivitis Sicca is a painful genetic disorder that is also known as Dry Eye Syndrome, keratitis sicca or KCS.
KCS is an inflammation of the cornea and conjunctiva due to an inability to produce watery tears. KCS prevents the eyes from being properly moistened, resulting in chronically dry, burning eyes and scarring.
With chronic KCS, the corneal surface thickens and becomes irregular resulting in pigmentary keratitis which eventually leads to irreversible blindness. In severe or chronic cases, keratitis may occur with erosion and painful ulceration of the corneal surface and photophobia (intolerance to light). Changes in the eye surface with decreased tear production predisposes the corneal surface to bacterial infections.
The most frequent cause is believed to be immune disorder that leads to decrease of watery component of the tear film. Approximately 72% of the dogs with KCS have the disease in both eyes. Other causes include:
KCS is a surprisingly common condition; in a study of dogs with eye problems, 40% were diagnosed with KCS.
Age at onset: KCS can occur at any age, but is most commonly seen in dogs of 6 to 10 years of age.
Symptoms: The earliest symptom of Dry Eye is conjunctivitis, or inflammation of the inner eyelids. Other symptoms include:
Genetics: The genetics of KCS in all breeds mentioned above has not been investigated.
However, in Cavalier King Charles Spaniels, KCS can be linked with another condition called Curly Coat Syndrome, and is often refered to as Dry Eye/Curly Coat or DE/CC. A recessive DNA mutation linked to KCS and curly coat syndrome (ichtyosiform dermatosis) in Cavalier King Charles Spaniels has been identified and serves as the basis for a genetic test available from Animal Health Trust. In addition to eye problems associated with KCS, dry eye and curly coat (DE/CC) affected dogs have very flaky and dry skin, particularly around the foot, which can make standing and walking difficult and painful. This syndrome appears to be a problem unique to CKCS and most dogs diagnosed with DE/CC condition are put to sleep.
We gratefully acknowledge Flo Sinclair, and her very special Holly Poppet, for her invaluable contributions to the sections of these articles describing Dry Eye/Curly Coat Syndrome in Cavalier King Charles Spaniels. Below is a photo of Holly Poppet, who has DE/CC Syndrome.
KCS in Humans: Dry eyes are common in Sjögren's syndrome, which is thought to be an autoimmune disorder and more common among women than men. Humans with KCS complain of irritation, burning, itching, a pulling sensation, pressure behind the eye, and a feeling as if something is in the eye. They say that symptoms improve during cool, rainy, or foggy weather and in humid places, such as in the shower.
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