Question of the Day

Use the Schirmer tear test (STT) in this dog with clinical signs suggestive of keratoconjunctivitis sicca (KCS or “dry eye”). A normal result for the STT is > 15 mm/min of wetting. A diagnosis of KCS is likely in dogs with ocular discharge, red eyes and a value of < 15 mm/min. In severe cases STT is < 5 mm/min.

KCS occurs due to an aqueous tear film deficiency seen most often in dogs (rare in cats). Present with bilateral mucopurulent ocular discharge, conjunctivitis, and superficial corneal vascularization/pigmentation. Can develop secondary corneal ulceration, it’s common, so use fluorescein dye to confirm.

It is most often due to an immune-mediated dacryoadenitis or idiopathic. Other causes include systemic sulfonamides, trauma, and iatrogenic secondary to removal of the third eyelid gland. 

Tx: Topical cyclosporine, artificial tears (e.g., hyaluronic acid), +/- topical steroids, +/- topical antimicrobials if corneal ulceration. Immune-mediated KCS typically requires life-long Tx.