Bovine viral diarrhea (BVD) is a contagious viral infection that affects cattle. It is caused by the bovine viral diarrhea virus, which can lead to various health issues, including respiratory problems, reproductive failures, and gastrointestinal disorders. The virus can be transmitted through direct contact with infected animals or contaminated environments. There are two main forms of BVD: the acute form, which causes sudden illness, and the persistent form, where infected animals may not show symptoms but can spread the virus. Vaccination and good herd management practices are essential for controlling the spread of BVD in cattle populations.