"There are poisons that blind you, and poisons that open your eyes" *

From St James Chronicle newspaper

It is quite rare for an obituary to be written for an animal but this donkey has left a small footprint in human history-even if it was unintentionally. Wouralia was part of an experiment that helped us to understand how the Wourali poison, or more commonly known as curare, works and to open new horizons in medicine.

Curare had been used for centuries from the indigenous people of South America, such as the Macusi Indians, at hunting. They would coat their arrows with a mixture where curare was the main ingredient. The poison would paralyse the animals by not letting them breathe. However, it is not poisonous if indigested; so the indians could eat the meat without any negative effects on them. The properties of curare were so valuable that its recipe was held as a sacred possession.

Charles Waterton, an English naturalist and explorer, spent nearly 20 years in South America exploring the Amazonian rainforest. In 1813, he achieved to bring to Europe an amount of the poison big enough to perform several experiments. 

One experiment that helped to redefine the history of 20th century medicine is the one with Wouralia. Together with Professor William Sewell, the director of the Royal Veterinary College at that time, Waterton tested the effects of the poison to three donkeys. They injected the first one in the shoulder, which then died in twelve minutes. The second donkey had a tourniquet placed around the upper part of one leg and the curare was injected under it. The animal walked around normally for longer than an hour without dying. However, when the tourniquet was released the donkey died within 10 minutes. The third animal, Wouralia, was injected with the same dose as the previous two. As Waterton has described in his Essays "Wanderings in South America" in 1825: 

The earliest clinical use of curare in humans was to ameliorate the tortuous muscle spasms of infectious tetanus, in 1858. Treatment of epilepsy, rabies, parkinson-like rigidity was also attempted by using curare.

However, it took about 100 more years for curare to find its real use in medicine. In 1912, Arthur Lawen used curare in surgery as an anasthetic but his work was ignored for decades partly because the published report was written in German. In 1942, Harold Griffith, the then chief anesthesiologist of the Montreal Homeopathic Hospital, performed an appendectomy on a young man anesthetized with curare. Satisfactory abdominal relaxation was achieved and the surgery proceeded without incident. He went on and used curare in several more surgeries all with positive results. After Griffith's report of his work, the use of curare and other synthetic curare-related muscle relaxants became the standard practice for several surgical procedures.

Before 1942, the patients had to inhale large, dangerous amounts of ether or chloroform before they would undergo surgeries that needed muscle relaxation. Curare had a profound effect on the transformation of anasthesia. Sedated and paralyzed patients could now successfully undergo the major physiologic trespasses of several types of surgery. Curare has since been replaced with manufactured muscle relaxants, but it pointed the way to a new era of safety in the field of anesthesia.

A little bit of science: 
The skeletal muscles get stimulated by a chemical named acetylcholine. Acetylcholine molecules get released in junctions between nerves and muscles; curare attaches to this junction blocking the transmission of acetylcholine. Until curare disintegrates, the nerve cannot trigger the muscle to act and the muscle stays paralyzed.

It is needless to say that there were several more scientists that studied the function of curare and helped to shape the science of anesthesia as we know it today that are not mentionned in this post.

*August Strindberg, The Ghost Sonata

Further reading:
1. Waterton and Wouralia, AT Birmingham, Br J Pharmacol, 1999 April; 126(8): 1685-1690
2. Curare and a Canadian connection, Charles Czarnowski, Can Fam Physician, 2007 September; 53(9): 1531-1532
3. Wanderings in South America, the North-West of the United States, and the Antilles, in the years 1812, 1816, 1820 and 1824: with original instructions for the perfect preservation of birds, &c for Cabinets of Natural History, Charles Waterton, 1825, London: J.Mawman