A study was made of the clotting defect and the course of the malady in a group of male dogs with an inherited, sex-linked bleeding disease. The clotting defect is characterized by a prolonged clotting time and a delayed prothrombin utilization, and is corrected by the addition either of thromboplastin or of normal plasma. A plasma protein fraction, fraction I, also corrects the defect. The defect appears to be due to a deficiency of a plasma factor, which normally, in the presence of platelets, makes thromboplastin available in shed blood. The clotting anomaly appears to be identical with that found in human hemophilia.
The hemostatic defect is characterized by repeated hemorrhages, usually without obvious relationship to trauma. Hemarthroses occur frequently and may result in permanent joint deformity. The animals usually die early in life from massive hemorrhage.
Transfusions with normal blood or plasma correct the clotting defect and readily control the hemorrhagic phenomena. By the use of transfusions, these dogs have been reared to maturity.