Bovine viral diarrhea virus (BVD) infection is responsible for a variety of economically important syndromes in beef herds. The economic losses from BVD infection will vary between herds based on herd immunity and stage of gestation at the time of exposure, the virulence of the BVD strain and other factors.
The virus is known to cause immune suppression, respiratory disease, infertility and fetal infection. Fetal infection (infection of the fetus during pregnancy) can lead to early embryonic death, abortion, birth defects, stunting, or the birth of persistently infected (PI) calves. Persistently infected cattle can result when susceptible pregnant cows are exposed to BVD virus during the first half of gestation and the virus passes from the dam to the fetus. Many times infected fetuses are aborted, but if a PI fetus survives to term, it will always have a tremendous amount of the virus in its body and cannot mount an immune response to clear the virus. A PI animal will secrete BVD virus throughout its life; in contrast to animals that become infected after birth that secrete the virus and are contagious for a few days to two weeks. These PI calves constitute the main reservoir and source of BVD virus for spread within the herd and to other herds of cattle.
Cattle persistently infected with BVD virus can be identified by a number of laboratory tests. Based on the NAHMS 2007-08 Beef Cow-calf study, while only 8.8% of U.S. cow-calf ranches had one or more PI animals identified; this means that one in every 11 to 12 herds have PI calves and most are not aware of their presence.
Vaccination programs can provide fairly good protection against BVD-induced disease when the exposure is from non-PI animals that are transiently infected with BVD. Vaccination programs offer some (but decreased) protection against BVD-induced disease when the exposure is from PI animals because of the tremendous amount of virus excreted by PI animals. Vaccination programs are an important component in BVD control, but will only offer a high level of protection if herd contact with PI animals is eliminated.
The cattle industry has made significant efforts in recent years to control BVD based on research that has provided a more complete understanding of the epidemiology of BVD, enhanced availability of diagnostic tests for detecting animals PI cattle, and a better idea of the economic impact BVD has on cattle herds. Our current knowledge of the epidemiology of BVD, the availability of efficacious vaccines, and the improvement in diagnostic tools have made the control of BVD feasible.
BVD CONSULT (Collaborative, Online, Novel, Science-based, Userfriendly, Learning, Tool) is an internet- based tool, designed to aid in the development of BVD control programs for cow-calf herds. It is the result of a multi-organization (AVC, AABP, NCBA) effort to combine available BVD research into a user-friendly and organized format to develop BVD prevention and control programs for individual herds that emphasizes key management decisions that impact the success of these programs.
BVD CONSULT provides bovine veterinarians with an opportunity to consult with their clients and develop BVD prevention and control programs for any cow-calf herd. For herds that currently have PI cattle present, the tool will help to create a plan to identify and remove the PI cattle and to establish a strategy to reduce the likelihood of the herd becoming infected again. For herds that are currently BVD-free, BVD CONSULT can be used as a producer and herd veterinarian decide how to minimize the likelihood of BVD virus entering the herd and to reduce the impact if the herd is exposed.
BVD CONSULT is set up as a series of questions with responses and was designed to mimic a conversation between a veterinarian and a producer who is concerned about BVD. The tool works through a decision tree in order to provide recommendations that are specific to individual operations. BVD CONSULT asks if the producer is willing and able to perform specific management practices that will aid in prevention or control and eradication of BVD. More information is available in the tool to help with the decision making process.
After clicking on “yes” or “no” to each question, an appropriate response is given based on the choices that have been made, followed by another question. The questions that are asked, and the responses given, vary depending on the previous answers. There are six to nine questions in total depending on the choices made. A printable report is available at the end of the tool which records the choices that were made and the responses that were given.
What BVD consult asks
The questions used in BVD CONSULT include:
• Do you have active BVD in your herd?
• Will you institute a testing strategy that identifies all BVD persistently infected (PI) cattle and remove them from your herd? (This question is seen by positive herds only. Producers of positive herds who choose not to test for PI cattle skip to question 6.)
• Will you quarantine and test all new cattle coming into your breeding herd?
• Can you prevent fenceline and direct contact of your pregnant herd with other cattle?
• If they cannot prevent contact: Are the cattle that your pregnant herd will have contact with likely to be infected with BVD (high risk or low risk contacts)?
• Will all cows calving in the same pasture calve in 90 days or less? (Can you prevent contact of newborn calves with cows that are less than 150 days of gestation?)
• Will you use an appropriate BVD vaccination strategy on heifers?
• Have the mature cows in your herd been appropriately vaccinated for BVD?
• Will you use an appropriate BVD vaccination strategy on mature cows? (Appropriate BVD vaccination strategies vary depending on the previous vaccination status of the mature cows.)
• Will you apply appropriate surveillance methods?
Bob Larson, DVM, PhD, Dipl. ACT, Dipl. ACVPM is a professor in production medicine at the Kansas State University College of Veterinary Medicine.
Sidebar: BVD consult
BVD CONSULT was created for the benefit of the beef cattle industry to enhance the control of BVD in beef cow-calf herds. This project was funded by an educational grant from Pfizer Animal Health and was produced by Brad White, DVM, MS (Kansas State University), Bob Larson, DVM, PhD (Kansas State University), David Smith, DVM, PhD (Mississippi State University), Daniel Givens, DVM, PhD (Auburn University), Dale Grotelueschen, DVM, MS (Zoetis Animal Health), Richard Randle, DVM, MS (University of Nebraska-Lincoln), and Sherri Merrill, DVM (Allen, Kan.).
BVD CONSULT can be found by visiting www.bvdinfo.org which contains a large amount of information about BVD from peer-reviewed articles as well as white papers and popular press articles.