Case history: A 5-month-old domestic shorthair kitten with a history of chronic left unilateral nasal discharge was examined.
Clinical findings: Endoscopy and computed tomography (CT) demonstrated a complete membranous obstruction of the left nasal choana, confirming congenital unilateral choanal atresia. In addition, congenital hydrocephalus was detected on CT. Nasopharyngoscopy was performed for confirmation and treatment of choanal atresia.
Diagnosis: Unilateral membranous choanal atresia associated with congenital hydrocephalus.
Clinical relevance: This report describes a rare congenital condition and for the first time, CT imaging provided an accurate diagnosis and allowed planning for the successful treatment of unilateral membranous choanal atresia. In addition, concurrent congenital hydrocephalus was diagnosed.