When dry eye (KCS) in dogs develops suddenly, you'll notice your pet has red, swollen, squinting eyes. You may also notice that there is a thick discharge in the corners of the eyes. After your pet has dry eye for a while, you'll notice that blood vessels have grown across the front of the eye.
Schirmer tear test (STT) measures the amount of tears made.
A tiny piece of paper is placed into the eye. The normal eye responds by making tears, and the tears are wicked down the paper. Dry eye is suspected if the tears reach less than 15-25 mm in one minute.
Fluorescence dye identifies scratches in the cornea.
Any nick in the smooth covering of the eye, the cornea, catches dye, which is easy to see with a black light. It is also possible to see the dye after it flows from the inside corner of the eye down through the nasolacrimal duct to drip from the nose. If dye doesn't flow out the nose, your veterinarian will check for a nasolacrimal duct obstruction.