If a dam has previously had a negative calf and then has a positive calf does she need to be tested? Yes. Unless the dam has already been directly tested. Related articles If a calf is positive for BVD virus is the dam also a PI? If a dairy cow is a PI what do I do with her milk? If I want to re-test an animal positive for BVD virus, how long should be left between the two tests? Comments 0 comments Please sign in to leave a comment.