Canine von Willebrand Disease - Inheritance

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Comparative Coagulation

Canine von Willebrand Disease - Inheritance

Inheritance and expression patterns of vWD differ between breeds. All males and females have 2 vWF genes, one inherited from dam and one from sire. In many breeds, the presence of 1 abnormal vWF gene appears sufficient to cause abnormal bleeding in some (but not all) dogs. Dogs having 2 abnormal genes express the most severe forms of vWD.

Breeding Recommendations Use vWD diagnostic ranges as guidelines to reduce the prevalence of vWD within a family or line, without discriminating against all dogs in that line. Screening for vWD will ensure that no severely affected puppies are produced.

Dogs that test in the normal range (vWF:Ag greater than 70%) are ideal for use in breeding programs. Matings between 2 vWD test-clear parents are predicted to produce only vWD clear pups. Progeny testing (testing parents and entire litter) is useful for confirming predicted genetic status based on a single vWF:Ag value. Progeny testing can help clarify the status of a borderline range parent.

In some cases, dogs that test in the vWD abnormal range (provided they do not express a bleeding tendency) may also be used for breeding. Carriers should be bred to test-clear, and ideally progeny test proven clear mates. Some puppies in these matings will test in the normal range. By increasing the number of clear to clear matings in subsequent generations, the proportion of vWD carriers in a line will be gradually reduced, without losing desirable traits. Carrier to carrier matings are undesirable, because these crosses are likely o produce the most severe form of vWD in offspring. Do not breed any dog that expresses abnormal or excessive hemorrhage.