Case description: A 12-year-old 500-kg (1,100-lb) American Quarter Horse mare was evaluated because of chronic mucopurulent, bloody discharge from the left nostril, inspiratory dyspnea, and respiratory noise.
Clinical findings: The horse had severe inspiratory dyspnea and stertorous respiration with no airflow from the left nostril. A temporary tracheostomy was performed. Endoscopy revealed a tan mass protruding from the left middle nasal meatus into the left common nasal meatus; it extended caudally into the nasopharynx and around the caudal edge of the nasal septum into the right nasal cavity. Radiographically, a soft tissue opacity was evident in most of the left nasal cavity and left paranasal sinuses. Cytologic examination of mass tissue revealed evidence of pyogranulomatous rhinitis; thickly encapsulated, budding yeast typical of Cryptococcus neoformans were detected.
Treatment and outcome: While the horse was sedated and in a standing position, the fungal granuloma was removed from the paranasal sinuses. Treatment with fluconazole (5 mg/kg [2.27 mg/lb], PO, q 24 h for 4 weeks) was initiated; enilconazole (50 mL of a 10% solution) was instilled into the paranasal sinuses every other day (7 lavages). Six weeks after surgery, infection had not recurred and epithelialization appeared normal in the left paranasal sinuses.
Clinical relevance: In horses with cryptococcosis of the paranasal sinuses, surgical removal of granulomatous lesions and systemic and topical administrations of antifungal drugs may be curative. Successful surgery may be performed in standing horses. Concommitant removal of a large portion of the conchae allows follow-up rhinoscopic evaluation of the paranasal sinuses.