| [suspicion of visna in a sheep from graubünden canton]. | a lentivirus belonging to the group of retroviridae causes a chronic progressive interstitial pneumopathy (maedi) or a demyelinating encephalo-myelitis (visna) in sheep and goats. pulmonary lesions of maedi as well as sero-positive, clinically healthy animals can be observed in switzerland; visna, which even in countries with endemic infection does not occur frequently, is extremely rare. the head and cervical spine of an ewe with severe nervous troubles suspected of scrapie were submitted for p ... | 1992 | 1439707 |