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
Breed(s): Rhodesian Ridgeback

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Common Symptoms

Hemophilia B (Rhodesian ridgeback type) is an inherited bleeding disorder affecting dogs. Hemophilia B (Rhodesian ridgeback type) is caused by a deficiency of coagulation factor IX, an essential protein needed for normal blood clotting. There is variation between breeds in the severity of the bleeding tendency with this disease. More severely affected dogs 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. A mildly affected dog may present with easy and excessive bruising and frequent nosebleeds. 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.

Testing Tips

Genetic testing of the F9 gene 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. Dogs 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]