Introduction
The majority of dry eye cases in cats are due to an infection with feline herpesvirus. In rarer cases, dry eye can be caused by injury or through removal of the third eyelid.
Causes of Dry Eye
Feline Herpesvirus
Dry eye in cats, also known as keratoconjunctivitis sicca or KCS, usually occurs as a result of chronic feline herpesvirus illnesses. This is a highly contagious respiratory disease, and once a cat has this disease it can be treated but never cured. The disease may remain in remission for years, but if the cat becomes stressed or ill it can emerge again and KCS may appear as a result. Cats and kittens that live in overcrowded and unsanitary conditions are at a high risk of becoming infected with feline herpesvirus. The good news is that cats can be vaccinated for feline herpesvirus, and as a result many cases of KCS in cats are preventable.
Removal of the Third Eyelid
Removal of the third eyelid due to cherry eye can also cause KCS because the third eyelid produces a great portion of the tears that keep the eye moist. Fortunately removal of the third eyelid is no longer a popular treatment for cherry eye. Instead, the eyelid is positioned back into place and tacked down to permanently hold it in its proper position.
Injury to the Eye
In rare cases KCS may be caused by an injury to the eye, but this can only happen if somehow the eyelid glands above the eye or on the third eyelid are injured. When this does occur, it is most often due to cat fight injuries.