Causes of von Willebrand Disease in Dogs
Von Willebrand disease is caused by genetic mutations that impair the synthesis, release, function or stability of von Willebrand factor. Males and females express and transmit these genetic mutations to their offspring with equal frequency. The severity of disease depends upon the degree to which the genetic mutations are expressed.
There are three recognized classifications of vWD, and affected breeds tend to fall into one of those three categories. Type 1 vWD is a quantitative reduction in the amount of circulating vWF and typically causes mild to moderate symptoms. It is the most common form of the disease and affects many breeds. Type 2 vWD is both a quantitative and a functional defect in vWF that causes severe signs, primarily in German Wireharied and Shorthaired Pointers. Type 3 vWD also causes severe disease; it predominates in Chesapeake Bay Retrievers, Dutch Kooikers, Scottish Terriers, Shetland Sheepdogs and occasionally other breeds. Type 3 vWD is a complete absence of detectable vWF in the affected dog’s blood.
Preventing von Willebrand Disease
Because of the strong genetic component, the only realistic way to prevent von Willebrand disease is to remove clinically affected animals from the breeding population. Dogs in predisposed breeds can be screened to ascertain whether they are deficient in von Willebrand factor. If they are, they should not be bred, even if they do not show symptoms of the disease.
Veterinarians have several fairly non-invasive ways to diagnose vWD. A DNA test is available to provide valuable information to breeders about identifying carrier and affected dogs. Most dogs with vWD have a good prognosis. With diligence and proper precautions, surgery and treatment of incidental trauma can be performed safely on dogs with this disease.