Haemophilia A - Old English Sheepdog

Haemophilia A is a monogenic X-linked recessive bleeding disorder. It is the most common inherited coagulation factor disease that affects many different dog breeds. It is described by a deficiency in a blood coagulation factor VIII, caused by mutations in FVIII gene. Coagulation encompasses a complex cascade where activated FVIII increases the catalytic efficiency of factor IXa in the activation of factor X. When mutated, FVIII cannot properly catalyse the efficiency of other coagulating factors, which leads to severe bleeding in joints and soft tissue. The symptoms include inadequate haemostasis, prolonged and excessive bleeding episodes, repeated formation of subcutaneous hematomas and unexplained lameness since birth. The current therapy requires the infusion of factor VIII-rich plasma concentrates during bleeding episodes but with possible risk of inhibitor antibody development when affected dogs with haemophilia A are exposed to factor VIII that does not match their underlying sequence. For the affected dogs that have extremely low levels of factor VIII, the bleeding episodes are life threatening.

Inheritance: X-linked recessive

Mutation: F8 gene

Genetic test: The method used for genetic testing is extremely accurate and allows complete differentiation between affected animals, carriers and healthy dogs. DNA testing can be done at any age.