[The determination of von Willebrand factor activity in the plasma of dogs. 1. Experimental evaluation and methods].

Using a new aggregometer, the plasma activity of von Willebrand factor (vWF) in dogs was measured. The method is described. It has the advantage of being more precisely for the diagnosis of von Willebrand's disease than the determination of von Willebrand antigen (vWF: Ag) by using an ELISA. With the method described reproducible and reliable result can be obtained.