BVD the Profit Robber

By Arden Wohlers DVM
Extension Veterinarian
University of Nebraska Panhandle Research and Education Center

Bovine Viral Diarrhea (BVD) as a disease entity has been identified for nearly 70 years, and cattlemen have annually used millions of doses of vaccine to harness the devastation it causes. It is estimated that the disease still costs the beef industry $7 billion a year and would be much higher if the vaccination wasn’t taking place. Current initiatives by the National Cattlemen Beef Association, American Association of Bovine Practitioners, the Academy of Veterinary Consultants and several state livestock associations to develop effective BVD virus control programs are underway. Research of BVD has raised as many questions as it has answered. But experts now believe there is enough understanding of the disease to greatly reduce its incidence or even eradicate it.

Clinical signs of acute disease include ulcers of the digestive tract and diarrhea that usually leads to death. Abortion, pneumonia and lameness are often signs of BVD infection. More damaging to the livestock industry is the reduced weight gains and increased susceptibility to other disease because of the immune suppression that BVD causes. The BVD virus has a high capability to mutate to circumvent an animal's immune response. This has resulted in many differing strains of the BVD virus. Some strains cause serious health problems, while others produce little to no signs of disease. The virus is usually brought onto a ranch by replacement animals that shed the virus in the air, manure and in body secretions. Animals that become infected with the BVD virus and survive will shed the virus for a few days, recover and become immune. The exception is the bovine fetus that is exposed between 30 and 125 days gestation, an age prior to the time when its immune system can eliminate the disease. These calves will be persistently infected (PI) and may live an apparent normal life. However they remain an incubator for the virus producing large numbers of viruses and therefore become a reservoir that efficiently leads to infection of other animals. Exposure to BVD from a PI animal can be so great that it may overcome the protection present in vaccinated animals. The nursing PI calf in a cow herd (even if the cows are vaccinated) will also create the next generation of PI fetuses.

There are no effective treatments for BVD. Control measures revolve around vaccination programs to increase disease resistance, eliminating the PI animals, and implementing biosecurity measures that prevent the introduction of disease onto the ranch. The cow/calf producer has the most to gain from the elimination of BVD. But a study by Dr. Guy Loneragan of West Texas A&M University also showed that feedlot pens with a PI animal or pens next to a pen with a PI animal had 40% higher incidence of respiratory disease. Recent developments in technology have made it easier to identify the PI animal so it can be eliminated. Methods for using this technology are currently being evaluated to find the most cost effective manner to eliminate BVD. Livestock veterinarians have developed protocols outlining the steps that producers need to take to eliminate the disease from their herds and greatly reduce the chances for its reintroduction.

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