Bovine Respiratory Syncytial virus (BRSV) has quickly become one of the major respiratory viruses in cattle in the U.S. Literary reports from various areas of the U.S. and Canada show that BRSV is present in 38 to 81 percent of the beef and dairy cattle tested. Bovine Respiratory Syncytial virus, first isolated in Switzerland in 1970 from an outbreak of respiratory disease involving dairy cattle, is a nonhemagglutinating pneumovirus in the family Paramyxoviridae. The virus was named for its characteristic property of promoting fusion of cells into multinucleated giant cells (syncytial cells).