Canine keratoconjunctivitis sicca (KCS) is characterized by chronic inflammation of the cornea, lacrimal gland, and conjunctiva, secondary to a deficiency of the precorneal tear film (PTF). Commonly referred to as dry eye syndrome, this condition is due to the lacrimal gland and/or nictitans gland’s insufficient production of the aqueous portion of the tear film.
KCS in dogs is not completely understood, however, many reasons are attributable including congenital, infectious, idiopathic, metabolic, neurogenic, drug-induced, iatrogenic, radiation, and immune-mediated (the most prevalent form in dogs).
KCS is often confused with bacterial conjunctivitis. When wrongly treated with topical antibiotics used to treat bacterial infections, the pet improves initially but the clinical signs resurface after the discontinuation of the treatment. If left untreated or not properly treated, the condition progresses to corneal opacification leading to blindness.
The worldwide used term “keratoconjunctivitis sicca” refers only to the later stage of the disease; broadly this is called “Canine Immune-mediated Lacrimal Syndrome (CILS)”.