– Dr. Lee Jones, DVM, Associate Professor, Department of Population Health, Food Animal Health and Management, Tifton Diagnostic and Investigational Laboratory
I’ve gotten several calls this fall asking about using modified live virus (MLV) vaccines in beef herds. Though modified live virus vaccines have been around for years and have been approved for use in adult cows for about 20 years there’s still a lot of confusion about using them.
First, I need to explain what is meant by MLV vaccines. The vaccines that contain Bovine viral diarrhea virus (BVD types 1 and 2), infectious bovine rhinotracheitis or also bovine herpesvirus type 1 (IBR), Bovine respiratory syncytial virus (BRSV) and parainfluenza 3 (PI3) come in 3 types – modified live, killed or combination (chemically altered). When we refer to ‘modified’ live or killed we are referring to virus vaccines. Not 7 way Clostridia (also called ‘blackleg’) or pinkeye vaccines or other bacterin or toxoid type vaccines. While there is a live bacteria vaccine for respiratory protection, it’s the virus part of the vaccine that causes the controversy. All MLV require mixing and they are clearly labeled on the front of the box MODIFIED LIVE VIRUS. The virus in these vaccines is alive and replicates in vaccinated animals causing a mild version of the disease. That’s how MLV vaccines work.
Why the controversy?
MLV vaccines can cause abortions if used in pregnant cows or heifers and can delay . . .
Continue reading Doc, how do I use a modified live vaccine in my cows?