Factor XI (FXI) is one of more than a dozen proteins involved in blood clotting. It is an inherited bleeding disorder that has been seen in humans, dogs and cattle (Gentry, 1984). The bovine form of disease was first discovered in Holstein cattle in Ohio in 1969 (Kociba et al, 1969). It was later observed in Holstein of other countries. It also goes by the name of hemophilia C in human. FXI is trace protein in the blood. It is produced in the liver. It plays a role in the coagulation cascade, the chain reaction that is set in motion when there is injury to a blood vessel. It helps in the activation of Factor IX, another blood protein important in the clotting process. 1348464350.php