A warning: the video above contains imagery of medical experiments conducted on animals that some might find disturbing.

In 1940, Soviet scientists reanimated a dead dog.

Dr. Sergei Brukhonenko had done pioneering work in blood transfusion several years earlier, a procedure which still remains essential in modern hospitals. But if you can move life-giving blood from one individual to another, why stop there?

While the Americans experimented on primates, the Soviet scientists experimented on dogs. Brukhonenko was able to isolate individual organs and maintain them in working order: a heart would keep pumping blood, lungs breathed on their own.

But those pieces, while important to life, do not a life make. The next step was to reanimate an entire head, brain, face and all, by pumping oxygenated blood through the arteries with the help of a contraption called the “autojektor.” With a blood supply to the brain, the head reacted to stimuli as it would in life, twitching its ears and eyes at pokes and prods. It even licked a substance off its own nose.

Next, another dog, this one completely intact, was given a clinical death, then brought back to life with the autojektor. “After the experiment,” the narrator of Experiments in the Revival of Organisms says over triumphant music, “the dogs live for years, they grow, they put on weight, and have families.”

Some have suggested that the whole thing is a hoax, an elaborate scheme to intimidate American scientists, but no evidence of fakery has been revealed. A contemporary video shows a puppy surgically attached to the torso of another dog, and images of a robot suit piloted by a dog’s head and brain have surfaced online. The only reason these experiments haven’t been recreated since is that the blatant animal abuse and disregard for modern standards of medical ethics would turn stomachs even more that this 1940 video does.

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