The Bidens adopted their German shepherd Major from a Delaware shelter. Pet adoptions in the U.S. have helped enable euthanasia rates to drop. President-elect Biden will bring with him to the White House his two German shepherds: Champ, pictured here, and Major, who will be the first shelter dog to ever live in the White House. The news has thrilled animal lovers, reflecting a growing embrace of rescue pets. MAJOR THE GERMAN shepherd spent his puppyhood in an animal shelter. In January, he’ll move into the White House. After four…