Identifying BVD

BVD-infected cattle cannot be identified visually, but multiple diagnostic tests are available to diagnose this infection. The PI calf as described above is the source for many infections and is the focal point for many diagnostic procedures.

If PI calves can be removed from the herd prior to exposure of pregnant cows, this can stop the disease from progressing to the next generation of calves. Because PI calves are born with the infection and shed throughout their lives, the diagnostic test can be performed at any time.

If a herd is suspected of harboring BVD, testing young calves prior to bull turnout is a good method to find the PI animals and remove them from the herd. It only takes one BVD-PI animal to perpetuate the disease in the herd, so testing all calves is necessary (and the dams of any calves identified as a PI calf).

There is no treatment or cure for BVD-PI animals, and there are very limited options for managing cattle diagnosed with BVD-PI. One recommendation is euthanasia to prevent further spread of disease. Another is to house them separately from the rest of the herd to feed them for harvest (meat is safe for human consumption).

There are multiple challenges with feeding them separately from the herd, including maintaining good biosecurity and the likelihood that many of these animals will die from other causes prior to reaching finishing weight.

BVD prevention

The ideal for BVD is to keep this virus from entering the herd. There are a few important biosecurity measures and vaccination plans that can help protect the herd. The biggest biosecurity risk is exposure of cows less than 4 months of gestation to potential BVD virus.

One potential source of exposure is stocker cattle or BVD-infected animals making contact with the pregnant cow herd. Another potential area for introduction of BVD is through importing pregnant animals that may be harboring a BVD-PI calf in utero. When bringing in pregnant animals that may have been exposed at a previous location, the only method to know the status of the calf is testing after the calf is born.

Several good vaccines are available to help prevent BVD infections and should be part of an overall vaccine strategy. Experimentation and field testing of these vaccines illustrates good efficacy at preventing infection, but overwhelming exposure to the virus (such as a BVD-PI animal being present in the herd) could lead to infections even in the face of proper vaccination.

Vaccines are a good safeguard, but should be used in conjunction with an appropriate biosecurity program. Work with your veterinarian to determine the best BVD preventative strategy for your herd.

Conclusions

BVD is a relatively uncommon disease, but cow-calf herd infection can lead to negative consequences. Understanding the best way to identify disease and how the virus is transmitted facilitates formation of the best BVD prevention and control strategy. Work with your veterinarian to determine which control techniques are best for your herd.

Editor’s note: Author Brad White is on faculty at Kansas State University College of Veterinary Medicine and serves as director of the Beef Cattle Institute. To learn more on this and other beef herd health topics, tune in to the weekly Beef Cattle Institute Cattle Chat and Bovine Science with BCI podcasts available on iTunes, GooglePlay or directly from www.ksubci.org.