Haemophilia B type 1 / factor IX deficiency (F9-related) - Cat

Haemophilia B in cats

This genetic test examines the F9 variant c.383G>A. Haemophilia B is also known as factor IX deficiency or Christmas disease. The F9 gene encodes clotting factor IX, a protein needed for blood to clot efficiently.

Cats with an affected genotype can produce too little functional factor IX. As a result, blood may clot poorly and bleeding can continue for longer after injury, surgery, dental procedures or birth. Bruising, delayed bleeding and internal bleeding may also be part of the condition.

What does X-linked recessive mean?

The F9 gene is located on the X chromosome. Male cats have one X chromosome and become affected when that X chromosome carries the variant. Female cats with one variant copy are carriers and can pass the variant on; female cats with two variant copies can also be affected.

Practical value of this test

• The test shows whether a cat is clear, carrier or affected for the tested F9 variant.
• For breeders, it helps avoid risk matings and manage the variant deliberately within breeding lines.
• For owners and veterinarians, the result gives valuable information for procedures, injuries and planning care around bleeding risk.