The vascular lesions caused by leeches upon the blood vessels of their host cause blood naturally to coagulate. How does the leech solve this problem since it could be expected that the ingested blood would coagulate inside its body?
Ingested blood does not coagulate inside the leech (Hirudo medicinalis) because in its saliva there is a potent anticoagulant substance, a protein called hirudin. In the past leeches were largely used as medical treatment. Nowadays hirudotherapy is being used in patients with extensive and chronic inflammation of the skin, in prevention against tissue necrosis after some surgeries and in several others fields of Medicine.
