In a herd of dairy sheep several losses occurred due to a respiratory syndrome in combination with progressive wasting. Clinical and pathomorphological diagnostics of 3 sheep revealed the presence of cancerous masses in the nasal cavities. These neoplasms were identified as adenocarcinomas originating from the nasal mucosa. Etiologically, they were attributed to JRSV (Jaagsiekte Sheep Retrovirus) by detection of capsid protein 24 in western blot. The significance of the disease in Switzerland is discussed, also in the context of lung adenomatosis.