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von Willebrand's Disease Type III
Test Overview:
Von Willebrand’s disease is the most common inherited bleeding disorder in dogs and occurs when there is a lack of functional von Willebrand factor. Von Willebrand factor is needed for the normal adhesion of platelets and for normal blood clotting to occur. There are 3 types of von Willebrand’s disease, and type III disease occurs when there are undetectable amounts of von Willebrand factor in the blood of affected animals. This is a recessive disorder and is the most severe form of von Willebrand’s disease. This type of von Willebrand’s disease leads to severe bleeding disorders and episodes of bleeding, and these severe bleeding episodes can be seen in young dogs. Diagnosis may be suspected in a dog that has a bleeding problem but a normal PT and APTT (or a mildly prolonged APTT) and can be confirmed by testing for von Willebrand factor levels. There is a DNA test for several breeds. The Shetland sheepdog is most commonly affected by this form of von Willebrand's disease, and a DNA test exists to test for the disease in the Sheltie. Bleeding can occur after trauma, surgery or may happen for no apparent reason, and can be life-threatening. Some young animals may simply be found dead after severe internal bleeding overnight (for example). Signs of internal bleeding may include lethargy, inappetance, increased breathing rate and/or effort, and pale gums. Treatment can involve hospitalisation for blood and/or plasma transfusions and intensive care.
Category:
Haemolymphatic - Associated with the blood and lymph
Gene:
von Willebrand factor (vWF) on Chromosome 27
Variant Detected:
Deletion of C
Severity:
Moderate-Severe. This is a disease with significant welfare impact on the affected animal, in terms of clinical signs and generally reduced life expectancy.
Mode of Inheritance:
Autosomal Recessive
Recommended Screening:
1. DNA testing of all breeding animals performed prior to breeding – e.g. at 1 year of age. 2. Recommend DNA testing prior to any surgery (e.g. desexing). Can perform DNA test on puppies (ie at 8-12 weeks). 3. Test BMBT/von Willebrand factor levels prior to desexing or other routine surgery.
Research Citation(s):
Venta, PJ. et al. Mutation Causing von Willebrand’s Disease in Scottish Terriers. (2000) J Vet Intern Med 14;10-19.
Associated Breed(s):
Australian Terrier, Mixed Breed, Scottish Terrier , Shetland Sheepdog,
