Do PI animals shed a lot of virus?
Yes, PI animals shed several billion viral particles a day and serve as a reservoir of BVDV in a herd. Do PI animals remain in herds for a long time? Yes and No. Ninety percent of PI animals are culled from dairy herds before they reach 2 years of age but some PI animals can remain in the herd for several years. However, new PI animals are constantly developing as a result of fetal exposure to BVDV from PI animals. Remember that a persistently infected or PI animal is the only permanent carrier of BVD virus. Can I tell a PI animal by looking at it? Some PI animals are stunted and are poor doing but many appear normal and cannot be distinguished from non-PI animals. You must test an animal to determine if it is persistently infected with BVD virus. Can’t I control BVDV infection in my herd with a good strategic vaccination program? Yes and No. Vaccination usually protects animals from disease (illness and death) but does not protect them from becoming infected with the virus (subclinica
