von Willebrand’s Disease
What is von Willebrand’s Disease in dogs?
von Willebrand’s Disease (vWD) is believed to be the most commonly inherited blood disorder in dogs and definitely the most common bleeding disorder. It has had a number of different names given to it over the years including Pseudohemophilia, Vascular hemophilia, VWDII, VWDI and VWDIII. This autosomal recessive inherited disorder is widespread in the dog population and affects dogs from large to small and from a wide geographical origin. von Willebrand’s Disease has 3 different types, Type I, Type II and Type III. Type I is by far the most common and the most widespread with type III being quite rare. Essentially all types are a result of a lack of normal von Willebrand factor (Vwf) produced by the affected dog. This factor is a protein that plays a key part in the blood clotting process, so the lack of this factor results in prolonged bleeding for the affected dog. It’s absence or inefficiency impacts another blood clotting protein called Factor VIII. This disease is very similar in nature to haemophilia in humans.
Genetics of von Willebrand’s Disease in dogs
The 3 known types of von Willebrand’s Disease are all classified by the type of mutation of the VWF gene. Types I and II are the result of mutations at a single point on the gene (although at different points), and Type III arises from a part of the VWF gene being deleted. These mutations and deletion affect the production of von Willebrand Factor to be synthesised, released into the bloodstream or to remain as a stable protein while travelling through the circulatory system.
What is the severity of von Willebrand’s Disease in dogs?
von Willebrand’s Disease is considered to be of a medium to high level of severity as it depends on both the type of von Willebrand’s Disease, as well as the level of vWF available to the affected dog. The severity of the symptoms are often able to be correlated fairly well with the level of working vWF, so generally speaking, the less vWF available, the more severe the symptoms.
What are the symptoms of von Willebrand’s Disease in dogs?
As with haemophilia in people, dogs affected by von Willebrand’s Disease may suffer from bleeding from mucosal membranes such as the inside of the nose, blood in the urine, skin bruising from light impacts, blood in the faeces, gum bleeding, prolonged bleeding after cuts or abrasions and of course, prolonged bleeding after and during surgery.
Diagnosis of von Willebrand’s Disease in dogs
Diagnosis of von Willebrand’s Disease usually occurs after an incident of prolonged bleeding without another explanation. Coagulation tests can be performed by the treating veterinarian to test the clotting ability of the dog’s blood. It is difficult to assign a lack of clotting specifically to von Willebrand’s Disease as a number of other diseases and factors may be responsible. A DNA Disease Screen will be able to detect the mutations responsible for von Willebrand’s Disease and give a more definitive diagnosis.
Treatment of dogs with von Willebrand’s Disease
Although an affected dog may suffer from random bleeds and other minor symptoms of von Willebrand’s Disease, the major risk to affected dogs is the risk of prolonged bleeding after an injury or surgery. Blood transfusions can be performed to supply the blood with von Willebrand Factor and component therapy including fresh frozen plasma can be administered to affected dogs prior to undergoing surgery. Most dogs can live out normal lives with reasonable precaution to avoid injury and not require very much special treatment except during times of excessive bleeding.
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