FILE - This undated electron microscope image made available by the Centers for Disease Control and Prevention shows rabies virions, dark and bullet-shaped, within an infected tissue sample. All dogs coming into the U.S. from other countries must be at least 6 months old and microchipped, according to new government rules published Wednesday, May 8, 2024. The new rules were prompted by concerns about dogs coming from countries where rabies is common, and applies to dogs brought in by breeders or rescue groups as well as pets traveling with their U.S. owners. (F. A. Murphy/CDC via AP, File)