von Willebrand’s Disease

von Willebrand’s disease is an inherited bleeding disorder of dogs. Dogs with von Willebrand’s disease are deficient in a protein called von Willebrand factor (vWF). This protein is important to prevent bleeding. Usually, when a blood vessel is damaged, cell fragments in the bloodstream called platelets form clots to seal the vessel and prevent further bleeding. von Willebrand factor helps with this clotting process.

The deficiency in this protein means that dogs with the disorder do not form clots as easily and are more prone to bleeding.

There are three forms of the disease which vary in severity. Types 2 and 3 tend to be clinically more severe whilst Type 1 varies in presentation but is usually mild. At least 30 different breeds are known to be affected by the disease.

Doberman Pinschers are the most commonly affected breed (up to 73% affected to some degree), but they usually suffer from the mildest form (Type 1). Other breeds reported as being carriers of the Type 1 variant include Shetland Sheepdogs, German Shepherds, Dachshunds and Poodles amongst others. Dog breeds reported as carrying more severe forms of the disease include Scottish Terriers (Type 3), Chesapeake Bay Retrievers (Type 3), German Shorthaired Pointers (Type 2) and German Wirehaired Pointers (Type 2).

Symptoms of the disease range from mild to severe. Some dogs with von Willebrand’s disease will never show any symptoms. Others may present with excessive bleeding or bruising after surgery or trauma. Your vet may suspect your dog is suffering from a bleeding disorder if, for example, your dog shows signs of prolonged bleeding during or after neutering surgery. Excessive bruising around the incision site can also be a sign of the disease.

Dogs may also show signs of prolonged bleeding during heat or after giving birth and puppies may bleed excessively after losing their temporary teeth. Dogs with severe forms of the disease may spontaneously bleed from the nose, mouth, bladder, anus or vagina. It is possible for a dog with the disease to go from having no symptoms in early life to more severe symptoms in later life.

In the first instance, your vet may perform a Buccal Mucosal Bleeding Time (BMBT) test if they are suspicious that your dog is affected by the disease. This test will not accurately diagnose the disease, but it can help you and your vet to decide whether to pursue further testing.

Your vet will use a special device to make a small incision on the underside of your dog's lip or cheek. They will then record the time it takes for the incision to stop bleeding. The incision made during this procedure is tiny and it should cause minimal pain to your dog. However, this type of test is not suitable for dogs who will not tolerate restraint for at least 5-10 minutes. If the incision takes over 4 minutes to stop bleeding, this indicates that your dog may have a clotting disorder such as von Willebrand’s disease. Dogs with mild von Willebrand’s disease, however, can have normal BMBT’s.

In order to obtain an accurate diagnosis of von Willebrand’s disease a blood test is required. Your vet will need to take a sample of your dog’s blood and send it to a laboratory. The exact amount of von Willebrand Factor in the blood will be measured and the result will be sent back to your vet.

The result of the test will help your vet to determine whether your dog is:

Dogs who are severely bleeding due to underlying von Willebrand’s disease are treated with blood transfusions, to replace blood cells and “top up” their vWF levels. Bleeding from minor wounds can be controlled with bandages, wound glue or sutures. A drug called Desmopressin can be used to treat the disease in some cases of Type 1, but is not always recommended. You should speak to your vet for further information about treatment options.

If your dog is diagnosed with von Willebrand’s disease your vet may warn you to avoid giving your dog certain medications. These medications can increase the risk of bleeding in dogs with the disease. They include some antibiotics such as sulphonamides, certain non-steroidal anti-inflammatory drugs such as aspirin, and a drug called heparin, amongst others. Before starting your dog on any new medications you should discuss possible risk factors with your vet.

If your dog requires surgery you should also talk to your vet about the risks involved; they may want to give a blood transfusion before surgery to help maintain clotting function. In the event that your dog has suffered a trauma your dog’s disease status should be brought to the attention of the responding vet as soon as possible.

It is possible to genetically test for the disease in many dog breeds. If your dog tests positive as a carrier of the disease, you should seek advice on breeding from your vet.