The gold standard diagnostic test. A drop of fluorescein dye is placed in the conjunctival sac. Under normal conditions, dye should appear at the ipsilateral nostril within 5–10 minutes. Failure to observe dye suggests complete obstruction. Delayed transit (>20 minutes) indicates partial obstruction.
Feline nasolacrimal duct obstruction is a manageable yet often chronic condition that requires a systematic diagnostic approach. The fluorescein dye transit test and ductal flushing remain essential diagnostic and therapeutic tools. Clinicians should differentiate congenital (breed-associated) from acquired (inflammatory, neoplastic, traumatic) causes to guide prognosis and treatment. While medical management suffices for mild cases, surgical bypass is available for severe, refractory obstructions. Further research into the role of viral rhinitis in chronic feline NLDO would improve long-term management strategies. cat blocked tear duct
Complete slit-lamp biomicroscopy should rule out corneal disease (ulcers, keratitis), uveitis, or glaucoma as causes of reflex tearing. The gold standard diagnostic test