Bovine viral diarrhea virus-induced abortion

Abstract

History and Clinical Signs : There frequently is a history of a febrile disease with signs compatible with bovine viral diarrhea (BVD) in the herd just prior to the occurrence of abortions. Abortion during the first trimester is usually undetected and is recognized as repeat breeding. Gross Lesions : There are no gross lesions specific for BVD abortion, however, teratologic defects such as cerebellar hypoplasia and alopecia have been found in calves infected in utero . Microscopic Lesions : Mild, localized vasculitis, mild placentitis with mononuclear cell infiltration, and reticuloendothelial hyperplasia especially of the hepatic portal areas and the lymph nodes are common, though not specific lesions. Cultural Procedures : The BVD virus is not usually present in the fetus aborted due to BVD infection and the presence of the BVD virus in an aborted fetus does not necessarily indicate that BVD was the cause of the abortion. Serologic Procedures : The appearance of BVD neutralizing antibody in aborting cows and other animals in the herd previously negative for this antibody or a 2 to 4 fold increase in BVD antibody titer indicates BVD has occurred in the herd. This evidence indicates that the abortion(s) may have been caused by this infection. The presence of active specific BVD neutralizing antibody in the serum of newborn or aborted calves indicates that they were infected with BVD virus in utero . The presence of such antibodies along with lesions and other significant findings will aid in determining the role of the BVD virus in abortion cases. Preferred Diagnostic Methods : 1. 1. Establish through herd history and serologic means that BVD infection was active in the herd just prior to or during the occurrence of abortions. 2. 2. Demonstrate the presence of active, specific BVD neutralizing antibodies in serum from aborted fetuses. 3. 3. Demonstrate fetal lesions and/or teratologic defects compatible with in utero BVD infection. 4. 4. Isolate BVD virus from aborted fetuses and correlate its presence with other significant evidence of its presence.