Chronic nasal disease is a common problem in dogs. To determine the aetiology, a retrospective study in 75 dogs with persistent and chronic nasal disease was done. All dogs were evaluated by means of survey nasal radiographs, antegrade and retrograde rhinoscopy, bacterial and fungal cultures, and histopathology. A definitive diagnosis was made in 74/75 cases (98.6 %). Nasal neoplasia was the most common diagnosis (46.7 %), median age 108 months, followed by lympho-plasmacytic rhinitis (20 %), median age 112 months, and fungal rhinitis (10.7 %), median age 53.5 months. Other diagnoses included nasal foreign body (5.3 %), median age 51 months, and primary bacterial rhinitis (6.7 %), median age 116.5 months. Rare aetiologies identified were nasal polyps, granulomatous rhinitis, oro-nasal fistula and naso-pharyngeal stenosis. This study showed that by using a structured combination of survey radiography, rhinoscopy, cultures and histopathology, a diagnosis could be made in dogs with chronic nasal disease.