Von Willebrand Disease (vWD) is an inherited blood clotting defect similar to hemophilia A in humans. Without the ability to clot blood, pets and people can experience prolonged bleeding from wounds and bruises and may experience internal bleeding from trauma.
In a normal animal’s system, platelets and the cells that line blood vessels are responsible for making protein complexes called von Willebrand factor. These proteins act like a glue that helps hold platelets together when they are called upon to seal up a tear in a blood vessel where bleeding is occurring. When the platelets do not stick together properly, prolonged bleeding occurs.
There are three types of vWD, and they vary in severity:
- Type I: All of the proteins that make up von Willebrand factor are present, but in smaller-than-normal amounts. This type of vWD is common in Doberman Pinschers, Shetland Sheepdogs, German Shepherds and Standard Poodles.
- Type II: The larger proteins making up von Willebrand’s factor are missing, leaving the smaller proteins to do all of the work. This results in more severe bleeding episodes than in Type I. This type of disease is more commonly seen in German Shorthair and Wirehair Pointers.
- Type III: There is no von Willebrand factor present. This is the most severe type of the disease, and is seen in Scottish Terriers, Chesapeake Bay Retrievers and Shetland Sheepdogs.
Von Willebrand Disease can occur in any breed of dog, but is most commonly seen in the breeds listed above. Generally, the condition is first recognized in puppies as a result of prolonged bleeding during a spaying or neutering procedure, or perhaps picked up in pre-surgical testing in at-risk breeds.
There are blood tests specific for von Willebrand Disease to measure the amount of von Willebrand factor present in the blood. Some veterinarians prefer to do a test prior to surgery to test how long it takes the pet’s blood to clot. This is easily performed under anesthesia just prior to surgery. A tiny incision is made in the inside of the pet’s lip, and then the veterinarian times how long it takes to stop bleeding.
Additionally, DNA testing is currently available for 11 different breeds and can determine if a dog is clear of disease, a carrier or is affected by the disease. Because vWD is inherited, affected dogs and carriers of the disease should not be bred. Dogs that are at a higher risk of disease due to their breeds should be tested before breeding.
Mildly affected dogs generally do not need treatment, though special care should be taken to avoid injury. More severely affected dogs may need a transfusion of von Willebrand factor if prolonged bleeding occurs and will need transfusions prior to major surgeries.