The withdrawal of blood from the body as a form of therapy. Blood, sometimes in large quantities, is drawn through a phlenotomy incision (an opening in a vein, these days with a large gauge needle, historically with a special phlenotomy knife), with the aim of curing or preventing a disease. This was/is performed mainly in cases of acutelaminitis.

Surgical incision of a vein to remove a thrombus (blood clot) or insert a special catheter. Also used to refer to the puncturing a vein to draw blood (venipuncture) or to the process of blood letting.