On this day in 1667, King Louis XIV’s personal physician, Jean-Baptiste Denys gave a 15-year-old boy sheep’s blood, in what is later acknowledged as the first documented blood transfusion.
A graduate of Montpellier, Denys was fascinated by the emerging field of blood transfusions and had been involved in various experiments involving blood transfusions from calves to dogs, published in the Royal Society’s Philosophical Transactions. But for Denys, the real progress lay in the transfusion of blood in humans.
He received his first opportunity on 15 June 1667 when a 15-year-old boy was brought to his attention. The boy was drowsy and feverish after having been bled by leeches. Denys injected about 12 ounces of sheep’s blood into the boy, after which he is said to have “rapidly recovered from his lethargy, grew fatter, and was an object of surprise and astonishment to all who knew him.”
The first transfusion a success, Denys went on to carry out more transfusions. Unfortunately, due to the size of later transfusions and the lack of knowledge at the time on interspecies transfusions, subsequent transfusions were not as successful as the first and some of Denys’s subjects eventually died. As such, the practice provoked heated controversy in France and by 1670 was eventually banned.
Nonetheless, Denys laid the foundation for the elemental procedure known as blood transfusions. In 1902 Karl Landsteiner discovered the four blood groups, earning him a Nobel Prize and making blood transfusions safe and reliable. As such, Denys paved the way for the practice that would go on to save millions of lives around the world.
As for Denys, he quit the practice of medicine after his failed transfusion and never experimented with transfusions again.