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Haemophilia A / Factor VIII (German Shepherd Type)
Test Overview:
This is a relatively common inherited coagulopathy (blood clotting disorder) of dogs and is most commonly reported in the German shepherd dog, although it has been reported in most breeds. It is an X-linked recessive trait, which means it is almost always seen in male dogs (as they carry only one copy of the X chromosome). Many different genetic mutations can lead to haemophilia A, as occurs in people, making development of a DNA test across breeds very difficult. Factor VIII is a clotting factor that is essential to the normal clotting of blood. The amount of factor VIII in the blood of an affected dog can vary quite a lot, and depending on this amount signs may be mild, or severe enough to cause neonatal death (due to the trauma of the birthing process). In general however, severe episodes of bleeding may be seen following trauma, bleeding may be seen into joints or body cavities, and profuse bleeding may be seen following even minor surgery. Treatment of bleeding in the haemophiliac dog is via transfusion of blood or plasma, in order to provide adequate amounts of factor VIII for normal clotting to take place, and hence for bleeding to cease. There is no cure for haemophilia A. Current testing identifies the activity of factor VIII in the blood, and is generally performed at a specialised laboratory.
Category:
Haemolymphatic - Associated with the blood and lymph
Gene:
F8 on Chromosome X
Variant Detected:
Base Substitution c.98G>A
Severity:
Moderate. This disease can cause significant signs of discomfort and/or dysfunction in affected animals. It may involve relatively high treatment/management costs, and can sometimes reduce life expectancy.
Mode of Inheritance:
Autosomal X-Linked
Recommended Screening:
1. PT/APTT testing (i.e. coagulation profile at local laboratory) – APTT prolonged and PT normal with haemophilia (good screening test prior to desexing etc) 2. Factor VIII activity testing for all male breeding animals prior to breeding (e.g. at 1 year of age). Requires sample to be sent to specialised laboratory – contact your laboratory or Breed Club for details. This is the current testing used by German shepherd clubs within Australia for certification, and the sire and dam are also recorded. 3. Factor VIII testing can be carried out on any male animal if owner concerned. Ensure testing done prior to desexing (e.g. if coagulation profile is abnormal, recommend this).
Research Citation(s):
Vet Rec. 2011 Nov 5;169(19):496b
Associated Breed(s):
German Shepherd Dog, Mixed Breed, White Swiss Shepherd,
