Canis ISSN: 2398-2942

Factor IX / Hemophilia B

Synonym(s): Factor IX deficiency, Christmas disease

Contributor(s): Prof Bernard Feldman

Introduction

  • Inherited X-linked recessive trait. Disease carried by females and affects males.
  • Factor IX is active in the intrinsic coagulation pathway.
  • Deficiency results in mild to moderate bleeding tendencies.
  • Most commonly seen as hematomas on body surface or hemarthrosis.
  • Prolonged bleeding after surgery or trauma.

Pathogenesis

Etiology

  • Same as factor VIII/hemophilia A Hemophilia A.
  • Genetic inherited disease, an inherited X-linked recessive trait.
  • Carried by heterozygous females; affects males and homozygous females.

Specific

  • Same as factor VIII/hemophilia A Hemophilia A.
  • Disease may manifest following vaccination with live vaccines which cause a temporary reduction in number and function of platelets.

Pathophysiology

  • Factor IX is active in intrinsic coagulation system. Together with factor VIII and calcium, it forms a complex which activates factor X (factor X is the first coagulation factor in the common pathway).
  • Factor IX deficiency results in hemophilia which may be mild to moderate in small breeds and severe in large affected breeds.
  • Manifests as hematoma formation and hemarthrosis which causes lameness, excessive bruising following trauma or prolonged bleeding after surgery, cuts, wounds.
  • Deficiency of factor IX causes prolongation of intrinsic coagulation cascade and so, ultimately, results in reduced conversion of fibrinogen to fibrin, which is necessary to stabilize the platelet plug which forms at sites of vascular injury.
  • Platelets function normally so a small endothelial injury may be sealed by a primary platelet plug. Therefore, do not see petechial/ecchymotic hemorrhages.
  • For larger injuries to vessels the platelet plug is not stabilized adequately by the coagulation cascade and so is washed away. Manifests as large bleeds - hematomas, hemarthrosis, bleeding at surgery.

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Fogh J M & Fogh I T (1988) Inherited coagulation disorders. Vet Clin North Am Small Anim Pract 18 (1), 231-243 PubMed.


ADDED