Von Willebrands Disease - Tests and Procedures

 (Please read in conjunction with the Client Information sheet on Von Willebrands disease)

Von Willebrands (VWD) disease is a very common inherited bleeding disorder affecting man and animals.  It is due to a deficiency of a special protein known as VWD factor antigen.  This is carried by the platelets which are blood cells that play a part in the clotting mechanism, helping to seal injured blood vessels.  When this factor is seriously deficient clotting is slow or non-existent and consequently even small haemorrhages can result in excessive blood loss.

Are many breeds of dogs affected?

The Doberman is probably the best known victim of inherited VWD.  Over fifty different breeds have been shown to be affected to date.

What are the signs?

Not every dog with VWD necessarily shows any signs.  Many live totally normal lives.  Therefore although there is an accurate, specific test for VWD factor antigen this, in the majority of cases, is only used when other tests to determine the source of any bleeding problem are negative.

"Not every dog with VWD necessarily shows any signs."

VWD tests are important in the case of breeding programmes involving any apparently normal dogs of any of the breeds that have been shown to be affected.

The usual signs are that the dog sustains a minor injury, e.g. a cut or graze that seems to bleed rather more profusely than would be expected.  

Should this dog then be tested for VWD?

Not necessarily unless it is one of the breeds known to suffer VWD, examples of which are Dobermans, Scottish Terriers, Shetland Sheepdogs, Poodles, Pembroke Welsh Corgis, etc.

What are the initial tests that are performed?

Excessive bleeding can be due to many factors of which VWD is only one.  Initially, routine blood tests including a complete blood count and a test of coagulation time will probably be carried out initially.  Another test frequently carried out in the surgery is a buccal mucosa bleeding time (BMBT).  This is a simple test in which an instrument is used to make a tiny prick on the dog's lip in order to measure the time taken for the blood to clot.

Once these results have been assessed it may then be necessary to take a blood sample that will have to be sent to a specialised laboratory for a VWD factor antigen assay.

If my dog is positive for VWD is there any treatment?

This inherited disease is, at present, incurable.  However prior knowledge that the dog is VWD positive is helpful and can avert unexpected emergencies.  For example, if you are prepared for the fact that a minor injury, e.g. a cut foot, could result in significant haemorrhage, you may, as a result, have appropriate dressings available.  Similarly the information can be invaluable should any major surgery be necessary in the future.  In addition, your veterinarian may be able to prevent haemorrhage during major surgery by administering blood plasma products and other specific treatments for the disease. 

If affected with VWD any dog intended for breeding obviously has to be critically assessed in view of the hereditary nature of the problem.

Can my dog lead a normal life?

Most dogs, even if affected with Von Willebrands Disease, lead perfectly normal lives.  However many drugs commonly used in treatment ranging from aspirin and antihistamines to analgesics and certain antibiotics are known to affect blood clotting and if these drugs are used in a dog with  VWD a major emergency can occur.