Von Willebrand's Disease in Dogs: Health Testing Guide

Von Willebrand’s Disease (vWD) is an inherited blood clotting disorder in dogs. It causes problems with blood clotting even from small cuts or internal injuries, posing a serious health risk. This condition is caused by a deficiency or dysfunction in Von Willebrand factor, a vital protein needed for healthy blood clotting.

vWD is named after this clotting protein. Without enough of this factor, a dog's blood cannot clot properly, resulting in prolonged bleeding even from minor wounds. Owners of affected dogs need to be vigilant about avoiding injuries and managing the condition carefully.

This disease is hereditary, passed down through genes from parents to offspring. For this reason, The Kennel Club and the British Veterinary Association strongly recommend testing dogs from breeds predisposed to vWD prior to breeding to prevent transmission to future generations.

Understanding Von Willebrand’s Disease in Dogs

There are three main types of vWD in dogs:

• Type 1: The most common and mildest form, characterised by a quantitative deficiency of Von Willebrand factor. Dogs with type 1 may show mild or no symptoms but can pass the gene on.
• Type 2: A less common form involving a qualitative defect, meaning the factor is abnormal but present.
• Type 3: The most severe form, where there is virtually no Von Willebrand factor, leading to a high risk of severe bleeding.

Symptoms often appear early in life, with pups bleeding excessively from the umbilical cord or during teething. Adult dogs may show signs like prolonged bleeding, blood in urine or faeces, frequent nosebleeds, or bruising. Type 1 can sometimes be asymptomatic, making testing important even if no signs are evident.

Breeds Commonly Affected by vWD

Over 50 breeds can carry the gene for von Willebrand's Disease, but some breeds are at particularly high risk, including the Doberman, Basset Hound, and Dachshund. For the most accurate breed-specific health testing recommendations, consult The Kennel Club's health test list.

Unlike haemophilia, which mainly affects males, vWD can affect both male and female dogs equally.

How is vWD Inherited?

vWD is an autosomal recessive genetic condition. Here’s how inheritance works:

• If neither parent carries the mutation, puppies will be clear of vWD.
• If both parents are affected, all puppies will have the disease.
• If one parent is a carrier and the other is clear, puppies have a chance to be carriers but usually won’t develop the disease.
• If two carriers mate, puppies run the risk of being clear, carriers, or affected depending on gene combinations.

This pattern means that carrier dogs can unknowingly pass the condition on without ever showing symptoms themselves, making testing essential.

Methods of Testing for vWD in Dogs

Two main tests are used to assess vWD status:

1. Blood-based Von Willebrand Factor Antigen Assay (VWF:Ag)

This laboratory test measures the quantity of vWF in the dog's blood, indicating functional clotting ability. Blood levels below 50% suggest the dog is at risk or affected, with severely affected dogs often below 25%. This test is commonly used to diagnose symptomatic dogs during veterinary assessments.

2. DNA Testing for vWD Type 1 Mutation

This genetic test identifies the specific mutation (c.7437G>A) responsible for Type 1 vWD in certain breeds. It is less invasive, using a cheek swab sample often collected at home. Dogs are classified as clear, carriers, or affected. This testing guides responsible breeding decisions to avoid producing affected puppies.

DNA testing is currently available for several breeds including the Doberman, Bernese Mountain Dog, Labradoodle, Poodle, Pembroke Welsh Corgi, and others. Mixed-breed dogs with ancestry from these breeds can also be tested.

Why Testing Matters

Testing helps identify carriers and affected dogs, enabling breeders and owners to avoid mating two carriers, thus reducing incidence of vWD in the population. For dog owners, knowing a dog’s status helps with managing bleeding risks and making informed health care decisions.

Combining both blood antigen and DNA tests offers the most comprehensive approach to managing vWD risk, supporting both diagnosis and breed health management.

Additional Tips for Owners

• Supervise affected dogs closely to prevent injuries.
• Avoid unnecessary surgeries or procedures with bleeding risk without veterinary advice.
• Inform your vet about your dog’s vWD status before any treatments.
• Regular check-ups and prompt treatment for bleeding episodes are vital.

Awareness and proactive testing are key to protecting dogs and improving breed health long term.