Genetic basis of Factor VII deficiency - in dogs this is an autosomal recessive inherited disorder caused by mutations in the F7 gene. This gene encodes factor VII, a vitamin K-dependent coagulation protein produced by the liver that initiates the blood clotting cascade. Dogs must inherit two copies of the defective gene (one from each parent) to develop the disease, while carriers with one copy usually show no symptoms but can pass the mutated gene to offspring. Breeds commonly affected include Beagles, Airedale Terriers, Dachshunds, German Wirehaired Pointers, and Schnauzers.
Pathophysiology - Factor VII plays a critical role in initiating the extrinsic pathway of blood coagulation by activating factor IX and X in the presence of tissue factor and calcium. When factor VII is deficient or dysfunctional, the blood clotting cascade is impaired, leading to delayed or inadequate clot formation. This results in increased bleeding tendency after injury or surgery, spontaneous bleeding episodes, and prolonged clotting times primarily seen as prolonged prothrombin time (PT), while activated partial thromboplastin time (aPTT) is usually normal.
Complications - Excessive or prolonged bleeding following trauma, surgery, or dental procedures. Spontaneous bleeding from mucous membranes such as gums and nose. Formation of hematomas or bruising without obvious cause. Joint bleeding that may impair movement and cause lameness. Anemia arising from chronic blood loss, with clinical signs like weakness and pallor. Potential life-threatening hemorrhage in severe cases if untreated.
Why This Matters to Breeders and Vets - Breeders: Genetic testing is essential to identify carriers and avoid breeding two carriers, which significantly reduces the risk of producing affected puppies. Genetic counseling promotes responsible breeding to manage the disease in predisposed breeds. Veterinarians: Early recognition via history, clinical signs, and coagulation testing (prolonged PT) supports diagnosis. Management includes preoperative screening to prevent fatal bleeding events and treatment of acute bleeding episodes with plasma transfusions or recombinant factor VIIa where available. Long-term care focuses on injury prevention and careful medication use. Awareness and proactive measures by vets and breeders are crucial for improving the quality of life for affected dogs and reducing prevalence in the population.
Summary - Factor VII deficiency is a rare, autosomal recessive bleeding disorder in dogs caused by mutations in the F7 gene, resulting in decreased or dysfunctional factor VII protein. It impairs the extrinsic blood clotting pathway, leading to excessive bleeding and bruising risks during injury or surgery. Diagnosis relies on coagulation testing and genetic analysis. There is no cure, but plasma transfusions and recombinant factor VIIa can manage bleeding crises. Preventive breeding using genetic tests is the most effective strategy to control this disorder in at-risk breeds.