I have to admit that when I saw a “LEECHES” link on davidgagne.net, I thought it was probably a derogatory term for some sort of weblogger behaviour. RIF, IHBA.
The leech’s main therapeutic benefits are not derived from the average 5 mls of blood removed during biting (although this may provide dramatic relief at first), but from the anticoagulant and vasodilator contained in the leech saliva. These properties permit the wound to ooze up to 50 mls of blood for up to 48 hours. Leech bites will bleed (ooze)an average of six (6) hours. The goal then is to produce an adequate venous outflow from the tissue by adjusting the number of leech applications and thereby bite wounds to suit the clinical applications