Factor VII deficiency

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Factor VII deficiency is a form of canine hemophilia.

Factor VII (Proconvertin) deficiencies are not normally associated with disease as hemostasis is initiated only by FVIIa bound to tissue factor, which constitutes only approximately 1% of total amount of the FVII protein existing in the blood[1]. Therefore, any resulting bleeding defect is normally mild.

Newborn pups have a very low plasma level of Factor VII and spontaneous and inherited deficiencies have been reported in the Airedale Terrier, Alaskan Malamute[2], Alaskan Klee Kai[3], Beagle, Giant Schnauzer and Scottish Deerhound. Although largely an asymptomatic defect, this autosomal recessive hemostatic disorder, can lead to excessive bleeding after surgery or trauma, hematoma formation, body cavity bleeding, and persistent uterine and vaginal hemorrhage[4].

Canine coagulation factor VII deficiency can be hereditary or acquired and may cause life threatening bleeding episodes if untreated.

Acquired deficiencies may occur associated with cholelithiasis[5], hepatitis, bacteremias[6] and dicoumarol poisoning.

A canine specific factor VII ELISA is available to diagnose this condition[7].

Routine coagulation screening tests can also be employed and unlike factor VIII or factor X deficiency, partial thromboplastin time in factor VII deficient dogs is usually normal.

Treatment usually involves use of frozen fresh plasma or recombinant factor VII[8] is available in life-threatening situations.

Use of recombinant factor VII offers only a temporary solution because the half-life of FVII protein is only 3 - 4 hours and, in canines, treatment with human proteins raises concern about antibody responses to those proteins, thus potentially limiting further therapy[9].

Gene therapy has shown promise recently, but has been complicated by the canine immune response to adeno-associated viral gene transfer vector capsid proteins used in canine patients[10].

References

  1. Reingardiene D & Lazauskas R (2009) Use of recombinant activated factor VII. Medicina (Kaunas) 45(3):248-253
  2. Mills JN et al (1997) Factor VII deficiency in an Alaskan malamute. Aust Vet J 75:320–322
  3. Kaae JA et al (2007) Hereditary factor VII deficiency in the Alaskan klee kai dog. J Vet Intern Med 21:976–981
  4. Wheeler SL et al (1984) Persistent uterine and vaginal hemorrhage in a with factor VII deficiency. J Am Vet Med Assoc 185:447–448
  5. Mayhew PD et al (2013) Evaluation of coagulation in dogs with partial or complete extrahepatic biliary tract obstruction by means of thromboelastography. J Am Vet Med Assoc 242(6):778-785
  6. Ogasawara S & Stokol T (2012) Interleukin-10 inhibits lipopolysaccharide-induced upregulation of tissue factor in canine peripheral blood monocytes. Vet Immunol Immunopathol 148(3-4):331-336
  7. Knudsen T et al (2011) Canine specific ELISA for coagulation factor VII. Vet J 190(3):352-358
  8. Giger U & Withnall E (2006) Effects of a minute and regular dose of recombinant human activated factor VII in beagles with hereditary coagulation factor FVII deficiency. ASH Annual Meeting Abstracts. Blood 108:1036
  9. Carlstrom LP et al (2009) Inadvertent propagation of factor VII deficiency in a canine mucopolysaccharidosis type I research breeding colony. Comp Med 59(4):378-382
  10. Nichols TC et al (2009) Protein replacement therapy and gene transfer in canine models of hemophilia A, hemophilia B, von willebrand disease, and factor VII deficiency. ILAR J 50(2):144-167
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