Genetic basis - caused by a mutation in the Factor IX (F9) gene located on the X chromosome. Factor IX is a crucial protein in the coagulation cascade, necessary for blood clotting. Mutations result in quantitative or functional deficiency of factor IX, impairing clot formation.
Pathophysiology - Deficiency of factor IX leads to impaired clotting and increased bleeding tendency. Dogs with severe deficiency have prolonged bleeding after trauma, surgery, or spontaneously. Spontaneous bleeding into joints, muscles, chest, or abdomen can occur, causing hematomas and swelling.
Complications - Severe hemorrhages following minor trauma or surgery. Spontaneous bleeding leading to chronic joint damage. Potentially fatal if untreated or undiagnosed. Management may require transfusions or plasma infusions during bleeding episodes.
Why This Matters to Breeders and Vets - Factor IX deficiency is a serious inherited bleeding disorder causing life-threatening hemorrhages. Genetic testing allows identification of carriers and affected dogs to prevent producing affected litters. Early diagnosis prevents complications from surgery or trauma and guides clinical management. Informed breeding reduces disease prevalence and improves breed health.