Epizootic hemorrhagic disease (EHD) is a hemorrhagic disease of white-tailed deer (Odocoileus virginianus) caused by an infection of a virus from the genus Orbivirus subsequently called Epizootic hemorrhagic disease virus (EHDV).[1][2] It is an infectious, and sometimes fatal, virus that is characterized by extensive hemorrhages, and is found throughout the United States. Large-scale outbreaks in wild ruminants affect livestock and the production industry.[3] EHD has been found in some domestic ruminants and many species of deer including white-tailed deer, mule deer, elk, and pronghorn antelope.[4] Seropositive black-tailed deer, fallow deer, red deer, wapiti, and roe deer have also been found, which essentially means that they were exposed to the disease at some time in the past but may not be involved in transmission. Outbreaks of EHD have been reported in cattle, although they rarely develop disease or die. Sheep may develop clinical signs, but this is also rare.[2] EHD is often called bluetongue, but this is incorrect. Bluetongue virus is closely related to EHDV, and has similar clinical signs, but it is a different disease. Bluetongue is a serious disease in cattle, as well as other ruminants, and can have a significant effect on international trade. Testing at animal health laboratories is necessary to distinguish between the viruses that cause bluetongue and EHD.