Von Willebrand disease (vWD) is the most common hereditary coagulation abnormality described in humans, although it can also be acquired as a result of other medical conditions. It arises from a qualitative or quantitative deficiency of von Willebrand factor (vWF), a multimeric protein that is required for platelet adhesion. It is known to affect humans and dogs (notably Doberman Pinschers), and rarely swine, cattle, horses, and cats. There are three forms of vWD: hereditary, acquired, and pseudo or platelet type. There are three types of hereditary vWD: vWD type 1, vWD type 2, and vWD type 3. Within the three inherited types of vWD there are various subtypes. Platelet type vWD is also an inherited condition.