FACTOR VII DEFICIENCY

 

What is Factor VII Deficiency?

Factor VII deficiency is a mild to moderate inherited blood clotting disorder. Affected dogs may appear mostly healthy but may be prone to increased bleeding tendency.

 

Mode of Inheritance and Explanation of Results:

Autosomal recessive (Two copies of the abnormal gene must be present in order for the disease or

trait to develop).   Alleles: N = Normal; FVII = Factor VII deficiency

  • Dogs with N/N genotype will not have factor VII deficiency and cannot transmit this FVII variant to their offspring.

  • Dogs with N/FVII genotype will not have factor VII deficiency, but are carriers. They will transmit this FVII variant to 50% of their offspring. Matings between two carriers are predicted to produce 25% factor VII deficiency-affected puppies.

  • Dogs with FVII/FVII genotype will have factor VII deficiency, a mild to moderate blood clotting disorder, and will transmit this FVII variant to all of their offspring.

Several hereditary bleeding disorders have been identified in many different canine breeds and involve clotting (coagulation) factor deficiencies, platelet disorders, and von Willebrand disease. Coagulation factor VII (FVII) deficiency has been known to occur in Beagles for decades, and there are a few reports of FVII deficiency other breeds. Very recently hereditary FVII deficiency was identified in an Alaskan Klee Kai dog and its family, as well as unrelated asymptomatic Alaskan Klee Kai dogs.   A DNA test to identify the mutation responsible for FVII deficiency in Alaskan Klee Kai dogs was developed at the University of Pennsylvania.

 

Dogs with hereditary FVII deficiency may exhibit an increased bleeding tendency following trauma or surgery or rarely appear to develop spontaneous bleeding. There are few reports of severe bleeding requiring blood transfusions, and some FVII-deficient dogs may remain unrecognized.  As this is an autosomal recessive disorder, the diseased/mutant gene (allele) may be unknowingly passed on through generations not only via asymptomatic carriers but also affected dogs, as they may not show obvious signs. Carriers have one mutant and one normal gene and appear clinically normal, but they can pass the defective gene to their offspring. 

 

Knowing which dog is a carrier or normal (clear) could allow for the targeted breeding of carriers with desirable traits to normal dogs without ever producing affected dogs, as long as the offspring are also tested and only clear dogs used thereafter.  

Reference: Orthopedic Foundation for Animals website: www.offa.org

Alaskan Klee Kai Association of America website:  www.AKKAOA.org

UC Davis Veterinary Genetics Laboratory website:  https://vgl.ucdavis.edu/