In 1954, Soviet scientist Vladimir Demikhov conducted a controversial surgical experiment in which he grafted the head, forelegs, and upper torso of a smaller dog onto the neck of a German Shepherd, creating a two-headed canine. Both heads retained autonomous functions: the secondary head could drink water (though it leaked from the esophageal stub) and react to stimuli, while the host dog's original head maintained full consciousness. The animals survived for four days before succumbing to tiss