Warning: Amazing but graphic photo of the ear before and after the surgery. Placed a pic of a bunneh first as to not subject the Odeck to it. Don't click through if you're squeamish about blood or detached body parts.
In short, a young woman lost her ear in a dog attack, and the nature of the injury made it difficult to reattach. While surgeons were able to attach an artery, they weren't able to do the same with a vein for draining the blood. As a solution, they used leeches until her ear was able to regrow the veins.