Most people that have spent time swimming in the freshwater lakes of Canada have seen or experienced a "leech attack". Leeches that drink blood have anti-coagulants and antiseptics in their saliva. Some injuries, such as the amputation of the end of a finger, can easily be surgically repaired, but the problem lies in restoring the venous system. Blood accumulates in the damaged tissue because the venous system can not drain the area as fast as the arteries supply it with blood. Leeches are applied to swollen areas because they extract the excess blood and as a result, decrease swelling. They are also used in plastic surgery where swelling inhibits healing.
HOW TO BEAT THE LEECHES