Balloon dilation and transient stenting of unilateral membranous choanal atresia in a British Shorthair cat with chronic purulent rhinitis and ascending meningoencephalitis.

Introduction: Choanal atresia is a rare congenital anomaly in humans and animals, characterized by the absence of communication of one or both nasal cavities with the nasopharynx. The severity of clinical signs depends on the presence of unilateral versus bilateral stenosis as well as comorbidities. With bilateral atresia, respiration may be severely compromised particularly during sleep, as airflow can only occur when breathing through the open mouth. Various therapeutic modalities have been described in people and adopted for animals. All treatments may be associated with complications, the most important being post-therapeutic scar formation with re-stenosis. This report describes a 10-month-old British Shorthair cat with chronic unilateral serosal nasal discharge that changed to mucopurulent discharge. When acute neurological signs developed, the cat was presented to the veterinary hospital. A diagnosis of primary, membranous right sided choanal atresia was achieved via computed tomography (CT) and nasopharyngeal (posterior) rhinoscopy. Secondary changes included destructive rhinitis with progression to the CNS with a subdural empyema and meningoencephalitis. Retinal changes and aspiration bronchopneumonia were suspected additional complications. After recovery from the secondary infections, the membranous obstruction was perforated and dilated using a valvuloplasty balloon by an orthograde transnasal approach under endoscopic guidance from a retroflexed nasopharyngeal view. To prevent re-stenosis, a foley catheter was placed as a transient stent for 6 days. The cat recovered uneventfully and was asymptomatic after the stent removal. Endoscopic re-examination after 5 months confirmed a persistent opening and patency of the generated right choanal passage. The cat remains asymptomatic 10 months after the procedure. Transnasal endoscopic balloon dilation and transient stenting of choanal atresia is a minimally invasive and relatively simple procedure with potentially sustained success.