Prion diseases or transmissible spongiform encephalopathies (TSEs) are fatal neurologic conditions of animals and humans. Animal TSEs include scrapie of sheep and goats; chronic wasting disease (CWD) of cervids, such as deer, moose, and elk; transmissible mink encephalopathy (TME); and bovine spongiform encephalopathy (BSE). Since 1990, scientists at the National Animal Disease Center (NADC) in Ames, Iowa, have studied cross-species transmissions of the scrapie, CWD, or TME agent into livestock and wildlife in an effort to identify the potential host range of TSEs and their clinicopathological and molecular features in a novel animal species. In this presentation, Juergen A. Richt, D.V.M., Ph.D., lead scientist and Veterinary Medical Officer at the National Animal Disease Center in Ames, Iowa, will address the various TSE cross-species transmission studies underway at the NADC and the molecular characterization of BSE cases identified in the U.S.