Haemophilia A / factor VIII deficiency (F8-related) - Old English Sheepdog

What does this test examine?

This genetic test analyses the F8 c.1786C>T variant in the Old English Sheepdog. The disorder is known as Haemophilia A, factor VIII deficiency, FVIII deficiency or classical haemophilia. The F8 gene is located on the X chromosome and encodes coagulation factor VIII, a protein required to form a stable clot after blood vessel damage.

What does Haemophilia A mean?

Dogs with an affected genetic result have strongly reduced or insufficiently functional factor VIII. As a result, blood clotting can be slow or incomplete. Typical problems include prolonged bleeding after minor injury, excessive bleeding after surgery or teething, bleeding from the mouth or nose, bruising, subcutaneous or muscle haematomas, lameness due to joint bleeding and, in severe cases, internal bleeding in the chest or abdomen. Severity can differ by variant and individual dog, but Haemophilia A is an important health risk that should be actively managed in breeding lines.

X-linked inheritance

Because the variant follows X-linked recessive inheritance, interpretation depends on sex. Male dogs have one X chromosome; when that X chromosome carries the disease variant, it causes the tested form of Haemophilia A. Female dogs with one variant copy are usually carriers and can pass the variant on unnoticed. A female dog with two variant copies has an affected genotype. This test makes hidden inherited risk visible before breeding choices are made or when a bleeding tendency needs genetic clarification.

Practical value of this test

This test is useful for breeders, breed clubs, veterinarians and owners who want to manage an F8 risk in a family line. The result helps avoid risk matings, identify carrier females and correctly assess expected risk in males.

• Helps prevent carrier females from being bred in combinations that can produce affected male puppies.
• Shows which dogs can pass the variant to offspring.
• Supports breeding plans in related dogs, family lines or breeds where this specific variant has been described.
• Adds genetic context for dogs with bleeding problems, haematomas, lameness from joint bleeding or unusual post-procedure bleeding.

Result in brief

• Clear: the tested variant was not detected.
• Carrier: one copy was detected; this is especially important in females, which can pass the variant on.
• Affected genetic result: in males, detection of the variant on the X chromosome causes the tested form; in females, two variant copies cause the tested form.