Keratoconjunctivitis Sicca (abbreviated KCS) is a disease involving inflammation of the cornea due to dryness or, more specifically, a tear film deficiency.  KCS or "dry eye" usually affects middle aged to older dogs and has been reported in cats.  KCS can be seen in any breed of dog, including mixed breed dogs.  The incidence of KCS has been especially well documented in the Miniature Schnauzer, Cocker Spaniel, English Bulldog, Beagle, Poodle, Pekingese, Shih Tzu, Lhasa Apso, Yorkshire Terrier and West Highland Terrier.

KCS results when there is a deficiency in the tear film.  The tear film is made up of three distinct parts: aqueous, lipid and mucoid.  The aqueous component is most often deficient, which leads to a build up of the other two components.  This build up leads to the typical "goopy" appearance of the "dry eye". There are many causes of the tear film deficit that leads to KCS including: drug therapy, trauma, autoimmune and canine distemper.  For the majority of KCS cases, no cause can be found.

Decreased moisture over the cornea (the clear portion of the eye over the iris and the pupil) leads to inflammation, edema, neo-vascularization and in chronic cases, pigmentation, keratinization and corneal ulceration.  Secondary bacterial infections are also quite common.

Clinical signs of KCS include mucous type discharge in  and around one or both eyes. Eyes which suffer from KCS are often red and appear irritated. Your pet may rub at its eyes. Animals with KCS are variably painful and are often observed to have a "painful squint".  Cloudy, vascularized and pigmented cornea as well as corneal ulceration are often observed.

Diagnosis of KCS involves an in depth eye exam. Suspicion of KCS, based on clinical signs, is confirmed using a Schirmer tear test and Rose Bengal staining if necessary.  Flourescein stain identifies corneal ulcers.  A complete CBC and serum chemistry panel are necessary to rule out systemic auto immune disease such as diabetes melitis, hypothyroidism, hypoadrenocorticism, immune mediated skin disorders as well as others.

Left untreated, KCS leads to blindness.  Medical treatment is very effective in early stages of the disease.  Correction of underlying systemic disorders is necessary.  Specific topical treatment for the eye(s) varies depending on severity and may include topical antibiotics, topical steroids and topical cyclosporine.  Cyclosporine inhibits immune mechanisms which in some cases lead to KCS. Medical treatment is usually quite intensive for several weeks and may require lifetime application of reduced doses of topical medication.  There are surgical options available for patients which fail to respond to medical treatment.