Factor VII Deficiency

What is Factor VII Deficiency in dogs?

Red blood cells ChevromistFactor VII Deficiency (FVII) is a bleeding disorder in dogs that is inherited in an autosomal recessive pattern. As the name suggests, dogs affected by this condition are deficient in the production of Factor VII. This blood protein is an essential part of the blood coagulation process. Like the relatively similar, but much more severe blood disorder haemophilia, Factor VII Deficient dogs may bleed heavily after injury as well as after even minor surgery. Often, most affected dog owners will be completely unaware that their dog is affected until their dog undergoes their first surgical procedure such as desexing (speying/neutering).

Genetics of Factor VII Deficiency in dogs

A point mutation on the F7 gene is responsible for Factor VII Deficiency in dogs, however if the dog carries only one copy of the mutated gene, it will not develop the disease. This is due to the autosomal recessive nature of the mutated gene. As long as one parent is clear of Factor VII Deficiency (ie. Two normal copies), none of the puppies that dog whelps or sires will be affected by the disease.

What is the severity of Factor VII Deficiency?

Factor VII Deficiency has a medium level of severity when compared to other genetic diseases. If affected dogs can be identified before they have surgery they can be managed quite well. Unidentified dogs however can present a problem for veterinarians not ready to stem a higher than normal level of bleeding by the affected dog during surgery. Most dogs with Factor VII Deficiency will still have a normal lifespan when compared to other dogs of the same breed.

What are the symptoms of Factor VII Deficiency in dogs?

The main symptom of dogs affected by Factor VII Deficiency is uncontrolled bleeding due to poor clotting times but there are other symptoms that are quite common in these dogs. They may bruise easily during rough play or after relatively minor injuries and unexplained nose bleeds may happen from time to time. Reports of dogs affected by Factor VII Deficiency having swollen glands around their neck have surfaced but the significance of these have yet to be determined.

Diagnosis of Factor VII Deficiency

Diagnosis of Factor VII Deficiency is usually made unexpectedly during surgery when there is uncontrolled bleeding. However a DNA Disease Screen will confirm definitively if a dog has Factor VII Deficiency as well as whether that dog is a carrier or if he is clear of mutated F7 genes.

Treatment of dogs with Factor VII Deficiency

Dogs with Factor VII Deficiency are not really treated, but are managed to avoid the risks associated with an uncontrolled bleed such as making sure there is extra blood banked in case the bleeding during surgery is excessive. Affected dogs are also often prevented from engaging in risky activities that may also lead to significant injuries to again prevent unnecessary risks to the dog.

References

Callan MB, Aljamali MN, Margaritis P, Griot-Wenk ME, Pollak ES, Werner P, Giger U, High KA. (2006) A novel missense mutation responsible for factor VII deficiency in research Beagle colonies. J Thromb Haemost. Dec; 4 (12):2616-22.

Callan MB, Aljamali MN, Griot-Wenkl ME, Pollak ES, Werner P, Giger U, High KA. Molecular characterization of hereditary factor VII deficiency in the beagle. J Vet Intern Med. 2005; 19: 448-449

Carlstrom LP, Jens JK, Dobyns ME, Passage M, Dickson PI, Ellinwood NM. Inadvertent propagation of factor VII deficiency in a canine mucopolysaccharidosis type I research breeding colony. Comp Med. 2009 Aug;59(4):378-82

Mills JN, Labuc RH, Lawley MJ (1997) Factor VII deficiency in an Alaskan malamute. Australian Veterinary Journal 75: 320-322

Noguchi M, Fujii T, Michizono A. (1987) [Congenital deficiency of factor VII in a canine family] Jikken Dobutsu. 36(4):423-30

Spurling NW, Burton LK, Peacock R,, Pilling T (1972) Hereditary factor VII deficiency in the beagle. British Journal of Haematology 23: 59-67

Spurling NW. (1986) Hereditary blood coagulation factor-VII deficiency in the beagle: immunological characterisation of the defect. Comparative Biochemistry Physiology A. 83(4):755-60

Withnall E, Giger U. Effects of recombinant human activated factor VII and canine fresh frozen plasma in Beagles with hereditary coagulation factor VII deficiency. J Vet Intern Med. 2006; 20: 766

 

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