Since the technology required to reattach a severed spinal cord has not yet been developed, the subject of a head transplant would become quadriplegic unless proper therapies, presumably along the lines of stem cell therapy, were developed. This technique has been proposed as possibly useful for people who are already quadriplegics and who are also suffering from widespread organ failures which would otherwise require many different and difficult transplant surgeries. It may also be useful for people who would rather be quadriplegic than dead. As of 2008[update], there is no uniform consensus on the ethics of such a procedure.
On May 21, 1908, Charles Guthrie succeeded in grafting one dog's head onto the side of another's neck, creating the world's first man-made two headed dog. The arteries were grafted together such that the blood of the intact dog flowed through the head of the decapitated dog and then back into the intact dog's neck, where it proceeded to the brain and back into circulation. Guthrie's book Blood Vessel Surgery and Its Applications includes a photograph of the historic creature. Were it not for the caption, the photo would seem to be of some rare form of marsupial dog, with a large baby's head protruding from a pouch in its mother's fur. The transplanted head was sewn on at the base of the neck, upside down, so that the two dogs are chin to chin, giving an impression of intimacy, despite what must have been at the very least a strained coexistence....too much time (twenty minutes) had elapsed between the beheading and the moment the circulation was restored for the dog head and brain to regain much function. Guthrie recorded a series of primitive movements and basic reflexes, similar to what Laborde and Hayem had observed: pupil contractions, nostril twitchings, "boiling movements" of the tongue.
The first dog heads to enjoy, if that word can be used, full cerebral function were those [of] transplantation whiz Vladimir Demikhov, in the Soviet Union in the 1950s. Demikhov minimized the time that the severed donor head was without oxygen by using "blood-vessel sewing machines." He transplanted twenty puppy heads—actually, head-shoulders-lungs—and forelimbs units with an esophagus that emptied, untidily, onto the outside of the dog—onto fully grown dogs, to see what they'd do and how long they'd last (usually from two to six days, but in one case as long as twenty-nine days).
In his book Experimental Transplantation of Vital Organs, Demikhov included photographs of, and lab notes from, Experiment No. 2, on February 24, 1954: the transplantation of a one-month-old puppy's head and forelimbs to the neck of what appears to be a Siberian husky. The notes portray a lively, puppy like, if not altogether joyous existence on the part of the head:
09:00 The donor's head eagerly drank water or milk, and tugged as if trying to separate itself from the recipient's body.
22:30 When the recipient was put to bed, the transplanted head bit the finger of a member of the staff until it bled.
February 26, 18:00. The donor's head bit the recipient behind the ear, so that the latter yelped and shook its head.
Demikhov's transplant subjects were typically done in by immune reactions.
In 1959, China announced they had succeeded in transplanting the head of one dog to the body of another twice.
In 1963, a group of scientists from Case Western Reserve University School of Medicine in Cleveland, Ohio, led by Robert J. White, a neurosurgeon and a professor of neurological surgery who was inspired by the work of Vladimir Demikhov, performed a highly controversial operation to transplant the head of one monkey onto another's body. The procedure was a success to some extent, with the animal being able to smell, taste, hear, and see the world around it. The operation involved cauterizing arteries and veins carefully while the head was being severed to prevent hypovolemia. Because the nerves were left entirely intact, connecting the brain to a blood supply kept it chemically alive. The animal survived for some time after the operation, even at times attempting to bite some of the staff. In 2001, Dr. White successfully repeated the operation on a monkey.
Other head transplants were also conducted recently in Japan in rats. Unlike the head transplants performed by Dr. White, however, these head transplants involved grafting one rat's head onto the body of another rat that kept its head. Thus, the rat ended up with two heads. The scientists said that the key to successful head transplants was to use low temperatures.
A human head transplant would most likely require cooling of the brain to the point where all neural activity stops. This is to prevent neurons from dying while the brain is being transplanted. Ethical considerations have thus far prevented any reported attempt by surgeons to transplant a human being's head.
