Von Willebrand's Disease
Causes, Symptoms and Treatment of von Willebrand's Disease in Dogs
This article is written by Pet Circle veterinarian, Dr Michelle Wong BVSc
Bleeding disorders are very concerning to the pet parent and can lead to a stressful time at the emergency centre. These disorders can be due to defects or deficiencies of platelets and clotting factors, either inherited or acquired, the latter being much more common. Of all the inheritable bleeding disorders, von Willebrand's disease is the most prevalent in dogs.
Von Willebrand's disease is a commonly inherited bleeding disorder in both humans and dogs. It is rarely seen in cats. This disease is characterised by a defect in the clotting factor, the Von Willebrand's factor, which normally acts as the 'glue' in holding platelets together to form a clot to stop the bleeding.
The Von Willebrand's factor is made of a protein complex and its purpose is to bind platelets together over the torn surface of the blood vessel. A defect in any of the proteins within this protein complex will result in von Willebrand's disease. While the platelet is held in place to stop the bleeding, fibrin is then produced to form a more permanent seal. Von Willebrand's factor also provides a small contribution in forming the fibrin clot.
There are three forms of von Willebrand's disease, defined by the quantity and quality of the protein structure.
von Willebrand's Disease Type 1
Type 1 is the most common. The proteins in the complex are low in number, although all types of proteins are present. Dog breeds which are affected by Type 1 include the Dobermann, the Shetland Sheepdog, the German Shepherd Dog, and the Standard Poodle.
von Willebrand's Disease Type 2
Type 2 von Willebrand's disease produces more severe bleeding episodes and is distinguished from Type 1 in that not only are the proteins in low concentration but there is abnormal structure and therefore function of the complex. This certain type may be more likely seen in German Short-Haired and German Wire-Haired Pointers.
von Willebrand's Disease Type 3
Dogs with von Willebrand's disease may appear quite normal until they show prolonged or excessive bleeding after injury or surgery. Spontaneous bleeding can occur in more severe cases, with noticeable bruising or bleeding from the nose without any history of trauma. The severity of bleeding can vary within this disease, ranging from mild to severe.
- Continued bleeding from injury or surgery
- Bleeding from nose
- Blood in stools or urine
- Tarry faeces
- Excessive bleeding in females after giving birth or during oestrus (on heat)
Von Willebrand's disease can be diagnosed with a simple blood test where the amount of von Willebrand factor is measured, and then this quantity is compared to the levels in normal dogs. The normal range that should be present is from 70-180% in dogs. 50-69% is considered borderline. Anything less than 49% is abnormal, these dogs are at risk of bleeding and should not be part of a breeding program. DNA testing may be available, discuss screening tests with your veterinarian if you plan to breed or your dog is an at-risk breed and you wish to check before surgery.
Von Willebrand's Disease has no cure. Dogs that are already bleeding can be given a blood transfusion containing the necessary clotting factors including von Willebrand's factor. A transfusion may also be given to dogs prior to a planned surgery. Dogs with von Willebrand's disease, or are carriers of the gene, should ideally not be bred to prevent passing on this disease to their offspring. This can help to limit the occurrence of this inheritable disease.
If you are considering getting a new puppy and concerned about genetic diseases, read our vet article on how to find a good breeder to compile your full checklist of questions to ask.
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