Nasolacrimal duct obstruction (NLDO), commonly referred to as a blocked tear duct, is a relatively common ophthalmic condition in domestic cats. The nasolacrimal duct system is responsible for draining tears from the ocular surface into the nasal cavity. When this system becomes obstructed, epiphora (excessive tearing) results, often leading to periocular dermatitis, cosmetic concerns, and in some cases, secondary infection. This paper reviews the anatomy of the feline nasolacrimal system, the various etiologies of obstruction (congenital and acquired), diagnostic techniques including the fluorescein dye transit test and dacryocystorhinography, and current medical and surgical management strategies. A focus is placed on breed predispositions, particularly in brachycephalic cats, and the importance of ruling out underlying causes such as neoplasia or chronic rhinitis.

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Congenital NLDO is most frequently observed in brachycephalic breeds such as Persians, Himalayans, and Exotic Shorthairs. Due to their flattened facial conformation, the nasolacrimal duct may be compressed, narrowed, or fail to develop a patent distal opening (functional imperforate punctum). In some kittens, the puncta may be anatomically absent (atresia).

Using a lacrimal cannula (e.g., 24-26 gauge), sterile saline is gently flushed through the superior punctum. Patency is confirmed if fluid flows freely from the nostril. Resistance or reflux from the same punctum indicates 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.