BVD Web Congress, Part 2: Diagnostics

More than 300 veterinarians from 10 countries gathered at various locations on March 30th to participate in the first Global BVDZero Web Congress, hosted by Boehringer Ingelheim. The U.S. assembly took place in Dallas just prior to the Academy of Veterinary Consultants Spring Conference.

The global event featured presentations from three prominent experts in Bovine Viral Diarrhea (BVD). These were:

·         Dr. Julia Ridpath, recently retired after studying BVDV and related pestiviruses at the USDA’s National Animal Disease Center (NADC) in Ames, Iowa.

·         Dr. George Caldow, Veterinary Manager, SAC Consulting Veterinary Services, a division of Scotland’s Rural College.

·         Dr. Dan Givens, Professor and Associate Dean for Academic Affairs, Auburn University College of Veterinary Medicine.

Part 1 of this series summarized Dr. Ridpath’s presentation. This installment focuses on Dr Caldow’s presentation titled “Herd level diagnostic approaches for BVDV.”

Caldow says the main priority in diagnosing BVDV is to detect the presence of persistently infected (PI) cattle. These are cattle infected in-utero when the dam is exposed during the first trimester of gestation. If the calf survives, it sheds the virus throughout its life. A related priority is to prevent naïve animals, such as new herd additions, young replacement heifers or feeder calves from exposure to PI animals.

Group or bulk testing can effectively monitor the BVDV status within a herd, Caldow says, adding that tests should be sensitive and specific and affordable. Spot samples of five animals, or bulk milk-tank samples, coupled with ELISA antibody tests or polymerase chain reaction (PCR) analysis, can detect exposure among other animals to determine whether whole-herd testing and control is necessary.

Caldow notes that maternal BVDV antibodies can persist for around 9 months in calves, and some PI animals can produce and test positive for antibodies, while also carrying the virus. He also discusses vaccine interactions with diagnostic tests.

In UK dairies, Caldow says, a typical BVDV surveillance system entails bulk-tank testing in the breeding herds, spot testing from groups of heifers older than nine months and testing all calves from heifer dams.

The next article in this series will summarize Dr. Dan Givens’ presentation titled “The impact and control of bovine reproductive pathogens.”

The archived presentations now are available for on-demand viewing on the BVDZero website. Once on the site, click on “Register Here” for a quick registration that will provide access to the presentations.