Dog - Von Willebrand's Disease

What is von Willebrand's disease?

von Willebrand's disease (vWD) is the most common inherited bleeding disorder of both man and animals.  It is caused by an inherited deficiency in the blood platelets' ability to stick to and seal damaged blood vessels resulting in excessive haemorrhage (bleeding).  The deficient protein is called 'von Willebrand factor antigen'.

Which breeds are most commonly affected by vWD?  

About 30 different breeds are known to be affected but the Dobermann is the breed most commonly associated with this disease.  Of 15,000 Dobermanns screened in the United States more than 70% were found to be carriers of the disease.  Fortunately, most of these are not clinically affected with any bleeding problem.  However, the number of Dobermanns with bleeding problems appears to be increasing.  Although Dobermanns are commonly affected, they usually have the mildest form of the disease and are, on average, 4 years old before diagnosis is made.

Other studies show that 30% of Scottish Terriers and 28% of Shetland Sheepdogs have abnormally low concentrations of von Willebrand factor.  The German Shepherd dog is also among the breeds affected.

What are the signs of vWD?

Many dogs with vWD never show outward signs of the problem.  Others may haemorrhage (bleed) from the nose, vagina, urinary bladder or oral mucous membranes (gums).  Prolonged bleeding after trauma or surgery is a common sign.  Females may bleed excessively while in oestrus (season, heat) or after giving birth.  In affected dogs uncontrolled haemorrhage may result in death.

How is vWD diagnosed?

A screening test known as 'buccal mucosal bleeding time', can be performed.  Prolonged bleeding time may be a sign of vWD especially in breeds known to be at risk.  The diagnosis can be confirmed with further tests which will measure the amount of vWD antigen present.

Owners of Dobermanns often report that the dog has undergone neutering, or other surgery as a pup without problems.  An uncomplicated recovery from such procedures does not eliminate the possibility that a dog may be affected.  Some dogs do not become obvious 'bleeders' until later in life.

Are there any situations which pose an increased risk if my dog is affected?

The avoidance of certain medications is critical for a dog with vWD.  Drugs that may precipitate a bleeding crisis for the dog include the following:

• Ampicillin/Amoxicillin
• Aspirin
• Antihistamines
• Heparin
• Ibuprofen
• Oestrogens
• Penicillin
• Phenothiazine tranquillisers
• Phenylbutazone
• Some sulphur-based antibacterials
• Theophylline (this substance is also present in chocolate)

These drugs should be avoided if at all possible, especially if the dog is in a bleeding crisis when presented.

Stress is thought to precipitate bleeding in people with vWD.  It is difficult to know if there is a similar association in dogs but the possibility should be kept in mind.

What can be done to treat dogs with vWD?

In an emergency situation, transfusion of blood or fresh frozen plasma may stabilise the patient.  The dog donating blood may be treated with a drug called DDAVP prior to blood collection which may affect the level of the von Willebrand factor in the donor's blood, with benefit to the recipient.

Some dogs with vWD are also able to increase the amount of platelet protein in circulation after the administration of DDAVP, although the response is variable.  The drug is expensive and not all dogs respond.

If I own a Dobermann that has always been healthy, should I do something?

Many Dobermanns affected with vWD will never have serious bleeding problems so the need for routine testing is debatable.  However, identification of dogs that have abnormal bleeding times is very valuable if surgery is planned.  Additionally, knowing that your dog is a carrier of vWD can be very important if an injury occurs and if the dog is part of a breeding programme.