Sulfonamide-associated keratoconjunctivitis sicca and corneal ulceration in a dysuric dog.

Long-term sulfonamide therapy for a urinary tract disorder was believed to have caused toxicosis of the lacrimal gland, and subsequently, dry eyes. Initial topical treatment of the ulcers may have potentiated the dry eye condition. The dog was referred with negligible tear production and bilateral corneal ulcers. Diagnostic evaluation of the urinary tract indicated reflex dyssynergia, a neurologic disorder causing functional urinary tract obstruction. The combination of appropriate topical and surgical therapy of the eyes, discontinuation of sulfonamide treatment, and initiation of bethanechol in the treatment of reflex dyssynergia all contributed to return of a normal tear film. Any combination of systemic and/or topical therapy may affect lacrimal secretion. The clinician must be cognizant of the potential effects that systemic medication, particularly antimicrobial drugs and drugs affecting the autonomic nervous system, may have on lacrimal secretions.