In 1926 a Finnish physician, Dr von Willebrand, discovered a clotting disorder. His primary research led to the discovery of a deficiency of a particular protein (the carrier protein for factor VIII), which was responsible for this clotting disorder. He discovered that though there seemed to be enough platelets, they were not ‘sticky’ enough to initiate clotting normally.
Von Willebrands is a bleeding disease. It is not sex linked, and is found in one form or another in over 30 breeds of dogs. It is not hemophilia but it’s the most commonly inherited bleeding disease of both people and animals. It is only one of many reasons that can cause abnormal bleeding in dogs. For many years it was a mystery why the disease was much milder in some breeds than in others (the Doberman an example of a mild form of the disease, the Scottish Terrier and example of the severe form of the disease). It is now understood that the mutation in the Von Willebrand’s factor gene in the Doberman causes faulty production 90 to 95% of the time, but 5 to 10% of the time the factor produced is normal and fully functional. As there are two genes for the factor, even with two of the mutant genes most Dobermans will produce 10-20% normal factor (and 80-90% non-functional factor). Under normal circumstances, this amount of factor is sufficient for normal clotting. In times of stress, or with major blood loss during surgery or as a result of trauma the disease may become clinically apparent with inability to clot. In other breeds such as the Scottish terrier, the mutation is more severe resulting in an almost complete absence of the factor, and in this breed a genetically affected dog is clinically affected as well.
In the past the ELISA test, which measures levels of the factor was the only diagnositic tool to differentiate between clear, carrier and affected Dobermans. This test was not very reliable, as there is much overlap in the amount of factor production between these groups of Dobermans. With great thanks to the research team headed by the University of Michigan geneticist Dr George Brewer, a joint effort between VetGen, Michigan State University and the University of Michigan developed a genetic test for this disease. Grant moneys donated from the DPCA, the Orthopedic Foundation of America, the Morris Animal Foundation, the DPFA, and the American Kennel Club made this possible. Now dogs may be definitively classified as clear, carriers, or affected by direct analysis for the actual genes.
In studies of healthy Dobermans, 35% are genetically affected (two copies of the mutant gene), 50% are carriers (one copy of the mutant gene) and 15% are clear (no copies of the mutant gene). Most Dobermans who are genetically affected will never have a bleeding problem. However, as times of stress or surgery may lead to bleeding problems, you may, as an educated Doberman Pinscher owner, opt to test your dog. One might request the vet keep desomepressin, and at times of scheduled surgery fresh frozen plasma, or cryoprecipitate (clotting factors) on hand, in case of emergency.
While most affected Dobermans may never show a sign of vWd, others may hemorrhage from the nose, gums, cuts, or genitals, etc… This usually comes after some minor type of injury. Some affected dogs go through protracted bruising/bleeding after a routine spay/neuter situation. Why some genetically affected Dobermans are clinically affected, while most are not, is not clear.
Cases of Dobermans having bled to death, due to von Willebrands, have been reported, although this usually occurs after some type of trauma. Most genetically affected Dobermans have injuries, and surgeries, without ANY complications. Some, years later have their first bleeding episode after a minor incident. Mostaffected Dobermans never have a bleeding problem. There are many other known, and some *unknown*, factors involved in bleeding situations. Stress is one, and there has also been some association between hypothyroidism and vWd bleeding episodes.
Many owners, and even some veterinarians become panicked at irregularities found in a Doberman, due to not being informed of the latest medical information. If a Doberman bleeds? Many will assume that it is automatically a vWd episode. So, this is why one would want to do the simple genetic test for vWd as soon as one obtains a Doberman. Knowledge is power.
A Doberman Pinscher who bleeds should NOT automatically be put down.
Some breeders will breed only clear to clear. However, our Doberman gene pool is already small and currently only 15% of the population tests clear. If we highly limited our accessible breeding stock, other problems will emerge as there are many genetic diseases affecting this, and other purebred breeds. vWD status is one of many factors considered when breeding. Further recommendations for use of vWD testing in breeding decisions can be found on the VetGen website.
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submitted by
Suzanne McDonald
edited by
Helayne Silver MD
DPCA Public Education Committee