From The Atlantic:
In 1908, Charles Guthrie was able to successfully amputate one dog's head and sew it onto the neck of another dog, rerouting the blood flow so that the animal had two (somewhat) functioning heads, according to Mary Roach's Stiff: The Curious Lives of Human Cadavers. "[T]oo 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," Roach explained.
Then, in 1972, scientists were able to transplant the head of a dying rich racist onto the body of Rosie Grier in The Thing With Two Heads:
But who's that third dude on the back of the bike? Only a daring jaunt on Netflix streaming will tell. In the meantime, apparently all that fuss with Rosie and his new racist friend would be have been unnecessary just a few years later, with this patented miracle technology:
Again from the Atlantic:
To solve that problem, scientists [in 1985] patented a device for perfusing an animal head. "This invention involves a device, referred to herein as a 'cabinet,' which provides physical and biochemical support for an animal's head which has been 'discorporated' (i.e., severed from its body)," the patent's abstract explains. "This device can be used to support a discorped head with oxygenated blood and nutrients, by means of tubes connected to arteries which pass through the neck. After circulating through the head, the deoxygenated blood returns to the cabinet by means of cannulae which are connected to veins that emerge from the neck."
Sounds easy enough, right? But then again, had such technology existed in 1972, or rather the 1972 of Thing With Two Heads, we would never have been treated to a timely morality tale built and accompanying incredible imagery: