Bovine viral diarrhea (BVD) is one of the most economically and welfare-significant cattle diseases globally, causing reproductive failure, immunosuppression, and the birth of persistently infected (PI) animals that spread virus continuously through herds.
BVD is responsible for enormous, largely invisible suffering in cattle herds. Mucosal disease in PI animals is profoundly distressing — these animals develop severe gastrointestinal and oral ulceration and inevitably die. The abortions and congenital defects caused by in-utero infection represent suffering for both the affected fetuses and the dam. The immunosuppression that accompanies BVD infection increases susceptibility to respiratory diseases that are themselves painful and debilitating. Critically, PI animals are frequently unrecognised — they may appear normal or only slightly stunted — and continue to spread virus to herd-mates for their entire lives. Identifying and humanely removing PI animals is both a welfare intervention for those animals (removing them from a life of ongoing immune dysfunction) and a herd welfare measure.