Hemophilia B (Rhodesian Ridgeback Type)

Other Names: Christmas disease, Factor IX deficiency
Affected Genes: F9
Inheritance: X-Linked Recessive
Mutation: chrX:109530868 (canFam3): G>A

Add To Cart Search Tests

Common Symptoms

Hemophilia B (Rhodesian ridgeback type) is an inherited bleeding disorder affecting Rhodesian ridgebacks. Hemophilia B (Rhodesian ridgeback type) is caused by a deficiency of coagulation factor IX, an essential protein needed for normal blood clotting. While there is some variation in bleeding tendency with this disease, Rodesian Ridgebacks most commonly present with severe bleeding after minor surgeries or trauma and occasionally exhibit spontaneous bleeding. Affected dogs may also bruise easily, have frequent nosebleeds, bleed from the mouth when juvenile teeth are lost, or show signs of lameness or stiffness if bleeding occurs in the joints or muscle. There is significant risk for prolonged bleeding after surgery or trauma, and in some cases, the bleeding may be severe enough to cause death. Veterinarians performing surgery on known affected dogs should have ready access to blood banked for transfusions. Most dogs will have a normal lifespan with this condition despite increased blood clotting times.

Breed-Specific Information for the Rhodesian Ridgeback

The Mutation of the F9 gene associated with hemophilia B (Rhodesian ridgeback type) has been identified in Rhodesian ridgebacks, although its overall frequency in this breed is unknown.

Testing Tips

Genetic testing of the F9 gene in Rhodesian ridgebacks will reliably determine whether a dog is a genetic Carrier of hemophilia B (Rhodesian ridgeback type). Hemophilia B (Rhodesian ridgeback type) is inherited in an X-Linked Recessive manner in dogs meaning that female dogs must receive two copies of the mutated gene (one from each parent) to develop the disease while male dogs only require one copy of the mutated gene from the mother in order to develop disease. Therefore, male dogs more commonly present with symptoms of the disease. Each male pup that is born to a female dog known to be a carrier of hemophilia B has a 50% chance of inheriting the disease. Reliable genetic testing is important for determining breeding practices. Because female carriers generally do not have features of the disease, genetic testing should be performed before breeding. In order to eliminate this Mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Rhodesian ridgebacks that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.


  • Mischke R, Kühnlein P, Kehl A, Langbein-Detsch I, Steudle F, Schmid A, Dandekar T, Czwalinna A, Müller E. G244E in the canine factor IX gene leads to severe haemophilia B in Rhodesian Ridgebacks. Vet J. 2011 Jan; 187(1):113-8. [PubMed: 20303304]