Diagnosis of Von Willebrand Factor in Dogs

Von Willebrand factor (vWF) plays a critical role in blood clotting. Without vWF, the blood cannot clot causing a potential health risk. Surgical procedures on dogs become extremely dangerous. If a dog is injured, he could bleed to death because the blood simply will not clot.

Dog Breeds Susceptible to Low VWF Levels

Nine dog breeds are extremely susceptible to von Willebrand's Disease. They include:

  • Doberman

  • German Shepherd

  • German Short-Haired Pointer

  • Golden Retriever

  • Miniature Schnauzer

  • Rottweiler

  • Scottish Terrier

  • Shetland Sheepdog

  • Standard Poodle

These breeds are routinely tested for vWF to make sure they are not bred. Many causes of von Willebrand's Disease believed to be genetic. By breeding dogs with normal vWF factors, the risk of the disease is lowered.

If you own one of these dog breeds, ask your veterinarian if you should have the dog's vWF factor tested. If you've purchased your dog from a breeder, ask to see the test results for both the canine parents.

The Role Von Willebrand Factor Plays in Healing

VWF is an amino acid protein found in the blood. It binds to other proteins allowing blood to coagulate. Then, platelets stick the site of a wound. Once the wound is sealed, blood will no longer exit the body and the healing process begins.

Testing a Dog's Von Willebrand Factor

The best way to test for vWF is a simple blood test. Your veterinarian will take a blood sample from your dog. The blood is tested to find out how much of that sample is made up of vWF when compared to a sample of blood taken from a normal dog. This percentage dictates the risk of von Willebrand's Disease in your dog.

  • 70 percent or greater is normal

  • 50 to 69 percent is considered borderline

  • Less than 50 percent is abnormal and signify the dog has a higher risk for von Willebrand's Disease

Test results may differ from day to day. In addition, concentrations of von Willebrand factor vary depending on where the blood sample is drawn. Therefore, your veterinarian may take a series of blood samples over a number of days. This ensures accurate results.

Von Willebrand's Disease Testing Before Surgery

If your dog is scheduled for a surgery, your veterinarian may require a test to check how fast your dog's blood clots. This test is performed by making a small incision in the dog's mouth and then timing the blood clotting. In a healthy dog, it will clot within four minutes. If it takes longer, von Willebrand's Disease may complicate the surgery.

Your veterinarian will likely continue with the surgery, but blood will be on hand for transfusions. By giving your dog blood that is rich in von Willebrand factor, clotting will take place as normal reducing the chance of losing too much blood.

The other option for treatment during surgery is a hormone supplement called Desmopressin Acetate. This hormone stimulates release of vWF. Use of this hormone supplement can improve blood clotting for about two hours.

Blood transfusions and hormone supplements are also useful in helping a dog that's been injured heal. By speeding up the blood clotting process, the dog is less likely to go into shock from loss of blood.