BVDV is an RNA virus and is closely related to the classical swine fever virus (CSFV) and the Border disease virus of sheep (BDV). All three viruses can induce cross-reacting antibodies to each other but there is evidence for a closer antigenic relationship between BVDV and BDV. Cross infection between cattle and sheep has been recorded.

BVDV exists in two different forms (biotypes) in the field; either non-cytopathogenic (BVDVnc) or cytopathogenic (BVDVc) virus. They are distinguished by their cytopathogenic effect when grown in cell culture. The two biotypes have different roles in the complex pathogenesis of BVDV infections.