leeches as a tool for preventing blood clot

During the 1800's, leeches were used as a tool for preventing blood clot. Leeches were so popular for this use that they became an endangered species.

The documented use of leeches in medicine stretches back to Greece in the 2nd century B.C.E. The bloodsuckers remained the physician�s standby throughout the Middle Ages�in fact, the modern word �leech� derives from the Old English word for �physician�� but during the 18th and 19th centuries, the practice boomed to a point that has been called �leechmania�. Believing that excess blood caused disease, doctors prescribed leeches for almost every ailment, from headaches to hemorrhoids.