Complete Guide to Von Willebrand's Disease Type II Testing in Dogs

Von Willebrand's Disease (vWD) is a hereditary condition affecting blood clotting in dogs due to a deficiency in the clotting protein called von Willebrand Factor. This guide focuses on the more severe Type II form, explaining which dogs are at risk, how the condition is inherited, and how owners and breeders can responsibly test their dogs for vWD Type II.

Understanding Von Willebrand's Disease Type II

Von Willebrand's Disease impacts the blood's ability to clot correctly, which can lead to excessive bleeding from minor injuries. Unlike haemophilia, which mainly affects males, vWD affects both male and female dogs. The disease has three types:

• Type I: The most common and mildest form with mild to moderate symptoms.
• Type II: A severe but less common form characterised by qualitative defects in the von Willebrand Factor.
• Type III: The most severe and rare form with acute symptoms and high health risks.

Dogs with hypothyroidism have a higher risk of developing vWD, often suffering from both conditions simultaneously.

Breeds Most at Risk of Von Willebrand's Disease Type II

This hereditary disorder is prevalent primarily in specific breeds. The German Wirehaired Pointer puppies and German Shorthaired Pointer puppies are particularly predisposed to vWD Type II. Crossbreeds with ancestry from these breeds may also carry the mutated gene but are less likely to be affected unless both sides of their lineage have the mutation.

How Von Willebrand's Disease Type II is Inherited

The disease follows an autosomal recessive inheritance pattern meaning that:

• Dogs can be classified as clear, carriers, or affected.
• Carriers show no symptoms but can pass the mutation to offspring.

Possible mating outcomes include:

• Two clear dogs produce a clear litter.
• Two affected dogs produce an affected litter.
• Two carriers produce a litter with 25% affected, 50% carriers, and 25% clear puppies.
• A clear dog and a carrier produce 50% clear and 50% carrier puppies.
• A clear dog and an affected dog produce all carriers.
• A carrier and an affected dog produce 50% carriers and 50% affected puppies.

Breeding decisions should be made carefully with knowledge of the dogs' statuses to avoid producing affected puppies while responsibly managing carrier dogs for the breed's genetic diversity.

How to Test Your Dog for Von Willebrand's Disease Type II

If you own or plan to breed German Shorthaired or Wirehaired Pointers, testing your dogs before mating is essential. Testing involves the following methods:

1. Genetic (DNA) Testing

• DNA tests identify the specific mutation causing vWD Type II.
• Samples can be collected via a cheek swab or blood sample and sent to approved veterinary laboratories.
• Results classify the dog as clear, carrier, or affected, helping breeders make informed decisions.

2. Blood-Based Functional Tests

• These assess the quantity and function of the von Willebrand Factor protein in the blood.
• Tests include Von Willebrand Factor Antigen (vWF:Ag) assays and collagen binding assays.
• Additional blood tests like a complete blood count and coagulation panel rule out other bleeding disorders.
• Functional tests can determine the dog's bleeding risk but are less specific for Type II without genetic confirmation.

3. Clinical Assessment

• Veterinarians may perform a buccal mucosal bleeding time test to assess bleeding tendency prior to surgeries.
• Testing is guided by clinical signs such as excessive bleeding after minor injuries or spontaneous bleeding episodes.

Combining genetic and functional testing offers the most accurate assessment. Discuss testing options with your vet to ensure the best approach for your dog.

Responsible Breeding and Managing Von Willebrand's Disease

Responsible breeders use vWD Type II testing results to avoid producing affected puppies. Carriers can be bred with clear dogs but require careful tracking of offspring status. This maintains breed health while preserving genetic diversity. Prioritising certified testing through approved laboratories ensures reliability and contributes to overall improve breed health standards.

Conclusion

Von Willebrand's Disease Type II is a hereditary condition that can seriously impact a dog's health due to impaired blood clotting. Recognising at-risk breeds like German Shorthaired and Wirehaired Pointers and conducting DNA and functional blood tests before breeding are vital steps in responsible dog ownership. Working closely with your veterinarian and reputable breeders will help protect your dog's wellbeing and support the health of future generations.

For more information, consider consulting The Kennel Club's health resources and approved veterinary genetic laboratories for testing services.