Bovine virus diarrhea--clinical syndromes in dairy herds.

Bovine Virus Diarrhea (BVDV) was diagnosed as the major etiological agent in 10 dairy herd disease outbreaks. The outbreaks varied between herds in time of onset in individual cattle, signs, morbidity, and clinical course. A definitive diagnosis was obtained by viral isolation from whole blood samples in each herd. Each herd problem and its clinical course was described in detail. A discussion of current knowledge pertaining to BVD--the disease and the virus--follows. The importance of strain variation relative to disease production and prophylaxis was highlighted.