What is von Willebrand’s disease?
Von Willebrand’s disease (VWD) is the most common inherited bleeding disorder in humans and dogs. It is caused by a deficiency in a protein called von Willebrand factor (VWF), which is essential for blood clotting. VWF helps platelets (the blood cells used in clotting) stick together and form clots to seal broken blood vessels.
Which breeds are most affected by VWD?
VWD affects at least 30 dog breeds, but the Doberman pinscher has the highest incidence of this disorder. Of 15,000 Dobermans screened in a research study, more than 70% were carriers of the disease. Most of these dogs were not showing signs of the disease when they were tested.
However, the number of Dobermans with a history of bleeding appears to be increasing. Although Dobermans are commonly affected, they usually have the mildest form of the disease. Their average age at diagnosis is about four years.
Another study showed that 30% of Scottish terriers and 28% of Shetland sheepdogs had abnormally low concentrations of von Willebrand factor. Chesapeake Bay retrievers and Scottish terriers are affected with the most severe form of the disease.
What are some of the signs of VWD?
Many dogs with VWD never show outward evidence of the disease. Others may spontaneously hemorrhage (bleed) from the nose, genitals, rectum, urinary bladder, or mouth. Prolonged bleeding after trauma or surgery is a common clinical finding, and bruising or bleeding after a surgical sterilization procedure (spaying or neutering) may be the first time any abnormality is noticed. Female dogs may bleed excessively after giving birth. In affected dogs with uncontrollable bleeding, death may occur.
How is VWD diagnosed?
Your veterinarian can perform a screening test, called the buccal mucosal screening time. Prolonged bleeding with this test can raise suspicion of the disease, especially in breeds known to be at risk.
To confirm the diagnosis, the exact amount of von Willebrand factor present in the blood can be determined through a laboratory blood test.
As puppies, Dobermans often undergo routine surgical procedures such as surgical sterilization, or cosmetic surgery such as tail docking. An uncomplicated recovery from such procedures does not eliminate the possibility that a dog may be affected by VWD. Some dogs do not become obvious bleeders until later in life.
Are there any situations that pose an increased risk if my dog is affected?
Certain medications may decrease platelet function and could increase the risk of spontaneous bleeding in von Willebrand’s patients. Some medications have been found to increase the risk of bleeding in humans, but specific research has not been done in dogs. For that reason, data from human medicine and human research is extrapolated to companion animals. Your veterinarian can advise you on the risk versus benefit of medications.
Drugs that may interfere with platelet function include:
- Ampicillin/amoxicillin
- Certain antihistamines
- Certain antacid medications
- Estrogens
- Heparin
- Nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin (ASA), meloxicam (Metacam®), carprofen (Rimadyl®), and deracoxib (Deramaxx®)
- Penicillin
- Phenothiazine tranquilizers
- Sulfa-based antibiotics
- Theophylline
In humans with VWD, emotional stress appears to precipitate bleeding in some cases. The subjective nature of such a finding makes it difficult to know if there is a similar association in dogs, although it is a possibility. Clients with dogs diagnosed with VWD should try to maintain a stress-free lifestyle, and the dog should be monitored closely for bruising or bleeding if they travel, have house guests, or experience other stressful events.
What can be done to treat dogs with VWD?
In an emergency, transfusion of blood or fresh, frozen plasma may stabilize a bleeding patient. The dog donating blood may be treated with a drug called DDAVP before blood collection. DDAVP will raise the level of von Willebrand factor in the donor’s blood, which benefits the dog with VWD.
Some dogs with VWD can increase the amount of von Willebrand factor in circulation after they receive DDAVP, although the response is variable. Currently, it is not recommended to use this drug on a regular basis. The drug is expensive, and not all dogs respond to it. Your veterinarian will discuss the treatment option and help you decide if it is an appropriate option for your pet’s condition.
My Doberman has always been healthy. Should it be tested for VWF?
Many affected Dobermans will never have bleeding problems, so the value of routine screening tests is debatable. If surgery is planned, including routine spays and neuters, it can be valuable to know if the dog has abnormal bleeding times. At minimum, a buccal mucosal bleeding time may be considered. Additionally, it can be very helpful to know your dog is a carrier of VWD if an injury occurs.
Screening for VWF is useful for breeders who strive to reduce the incidence of problems in their breed. Genetic (DNA) tests are available for susceptible breeds.
