Getting control of BVD for better health, performance

By working with their veterinarians to understand disease challenges and implement more aggressive prevention protocols, beef producers are seeing real improvements in overall health, performance and reproductive success. But the most common viral disease affecting beef cattle—bovine viral diarrhea (BVD)—continues to affect a high percentage of animals and cause significant economic losses.

BVD is a complex disease that consists of hundreds of different viral strains, making it difficult to diagnose and hard to control. One of the biggest problems is that 90 percent of BVD cases are subclinical. That means infected cattle don’t show visible signs of illness. So these cases usually go unnoticed and untreated. Meanwhile, these seemingly healthy cows can infect their herdmates and the number of cows carrying the BVD virus multiplies. 

The majority of U.S. beef cattle—60 to 85 percent—are exposed to the BVD virus at some point.¹ And because BVD is an immunosuppressive virus, much of the economic impact is the result of a weakened immune system, which often leads to secondary respiratory infections. The BVD virus is often a precursor to Pasteurella multocida, Histophilus somni and Mannheimia (Pasteurella) haemolytica, which all contribute to bovine respiratory disease (BRD) complex. Making matters worse, BVD infections are increasing 10 – 15 percent each year.²

Financial losses associated with BVD are difficult to pinpoint, because so many BVD infections go undiagnosed or are misdiagnosed. However, the annual economic loss for all U.S. cattle is approximately $3 billion.³ That’s why it’s really important for producers to work closely with their herd veterinarian to review and monitor BVD control programs on an annual basis.

Another problem with the BVD virus is its ability to cause persistently infected (PI) calves. PI animals occur when pregnant cows are infected with a specific type of BVD virus, referred to as “noncytopathic.” PI calves usually occur when unprotected cows are infected between 40 and 120 days of gestation.

BVD strains generally fall into two broad categories—Type 1 and Type 2—and these strains are further classified according to their biotypes, cytopathic (CP) and noncytopathic (NCP).  NCP is by far the more significant variation of BVD for beef producers. NCP BVD accounts for 90 to 95 percent of all clinical outbreaks.⁴ And the NCP biotype is responsible for all BVD PI animals, as well as most BVD-induced abortions.

The best thing producers can do is talk to their veterinarian about BVD prevention. The veterinarian can help ensure producers are taking the necessary biosecurity steps to control the BVD virus and minimize its impact on herd health and productivity. Testing for PI animals has become more common to determine presence of the disease within herds and as a way to identify and cull PI calves. 

Vaccination is a critical component of any BVD program that should be evaluated annually for performance. There are dozens of BVD vaccines available, but not all of them protect against the NCP biotype.  

For maximum herd protection, veterinarians frequently recommend choosing a vaccine that offers broad-spectrum coverage against field strains of both BVD Type 1 and Type 2 genotypes, including NCP protection. 

Good biosecurity is also critical to protecting a herd. Testing all incoming animals and keeping them separate from the rest of the herd until they are confirmed BVD-free is the best strategy. And culling PI animals rather than selling them is critical to the health of the industry as a whole.

References:

1. Houe H. Epidemiological features and economical importance of bovine virus diarrhea virus (BVDV) infections. Veterinary Microbiology. 1999;64:89-107.
2. South Dakota State University
3. Ridpath J. Why BVD is a tough problem. Hoard’s Dairyman. October 25, 2002:697.
4. Brock K. Department of Pathobiology, Auburn University College of Veterinary Medicine, Auburn, AL.