Health tests
Von Willebrand disease type 1
- How it is done
- DNA test
- Also called
- vWD1
- What it looks for
- The VWF c.7437G>A variant associated with von Willebrand disease Type 1 - a shortage of the blood clotting protein von Willebrand factor.
- Why it matters
- Von Willebrand disease is an inherited bleeding disorder caused by a lack or a reduced level of von Willebrand factor. How it shows varies from no signs at all to spontaneous haemorrhage and prolonged bleeding after injury, surgery or giving birth, and the age at which it shows varies too - some dogs only become obvious bleeders later in life. Without medical intervention, uncontrolled bleeding can result in death. Type 1 is the most common bleeding disorder in dogs and is generally less severe than Type 2 and Type 3, and it can be alleviated by treatment.
- How it is done
- A DNA test on cells brushed from the dog's cheeks and gums with a cytology brush; the laboratory supplies the brushes. The dog must not have eaten or drunk for at least an hour beforehand, and the laboratory recommends waiting until puppies are at least three weeks old.
- How it is inherited
- Autosomal dominant with incomplete penetrance - not all dogs that carry the vWF variant show clinical signs of the disease. A dog with N/N will not have von Willebrand disease Type 1 and cannot transmit the variant. A dog with N/vWF may be affected and develop the disease, and transmits the variant to 50% of its offspring. A dog with vWF/vWF may be affected and develop the disease, and transmits the variant to all of its offspring. There is therefore no safe "carrier" category here as there is for a recessive disorder: one copy already puts the dog at risk.
- For the breed
- General to all breeds
- What the results mean
-
- N/N — Two normal copies. The dog will not have von Willebrand disease Type 1 and cannot transmit the variant to its offspring.
- N/vWF — One copy of the variant. The dog may be affected and develop von Willebrand disease Type 1, and will transmit the variant to 50% of its offspring.
- vWF/vWF — Two copies of the variant. The dog may be affected and develop von Willebrand disease Type 1, a blood clotting disorder, and will transmit the variant to all of its offspring.
- Where the result is recorded
The sources disagree
Whether one copy of the variant puts a dog at risk, or only makes it a carrier.
-
According to
Flemish government breeding programme for the Cairn Terrier
Autosomal recessive ("Overerving: autosomaal recessief"), with the generic recessive breeding matrix applied to it.
If this is right: A heterozygous dog is a symptom-free carrier, and one clear parent is enough to license the mating.
-
According to
Veterinary Genetics Laboratory, UC Davis
Autosomal dominant with incomplete penetrance, for the same variant VWF c.7437G>A.
If this is right: A dog with one copy may itself be affected. There is no safe carrier category, and a mating licensed by the recessive matrix could still produce affected dogs.
-
According to
Autosomal dominant with variable penetrance. Its sister brand LABOGEN publishes the same test number for the same gene as autosomal dominant with incomplete penetrance. Neither page prints the variant coordinate, so the link to c.7437G>A rests on the other two sources.
If this is right: As above — one copy is already a risk rather than a carrier state. Same laboratory group as LABOGEN, so this is corroboration rather than a third independent opinion.
This site does not settle it. Both positions are shown with who holds them, because choosing one would mean overruling either a government decree or the laboratory that runs the test. Ask your own club which reading it applies.
Source: Von Willebrand Disease I (vWD Type 1) - test page, Veterinary Genetics Laboratory, UC Davis School of Veterinary Medicine, Quick Summary; Phenotype; Mode of Inheritance; Alleles; Breeds appropriate for testing; Explanation of Results; Sample Collection; Additional Details (No version label published on the page; content as retrieved 2026-08-11) — https://vgl.ucdavis.edu/test/vwd-type-1 · Explanations checked: 2026-08-11
Explanations checked: 11 August 2026