Von Willebrand?s disease (vWD) is a blood disease caused by a deficiency of von Willebrand Factor (vWF), an adhesive glycoprotein in the blood required for normal blood clotting. A lack of vWF impairs platelet stickiness and clumping. Symptoms can include: spontaneous hemorrhage from mucosal surfaces, nosebleeds, blood in the faeces, bloody urine, bleeding gums, excessive vaginal bleeding, bruising, prolonged bleeding after surgery or trauma, blood loss anemia. The inheritance of the severe forms (Types II and III) is autosomal recessive. The milder form (Type I) may be autosomal recessive or incompletely dominant. This is the most common hereditary blood clotting disorder in dogs.