Dog - Von Willebrand's Disease Tests and Procedures

(Please read in conjunction with the handout on von Willebrand's disease).

von Willebrand's (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 (thrombocytes) which are blood cells that play a part in the clotting mechanism, helping to seal any injured blood vessels.  With vWD clotting is slow or non-existent.  Consequently even small wounds can result in excessive blood loss.

Are many breeds of dogs affected?

The Dobermann is probably the best known victim of inherited vWD but it is not alone.  Over fifty breeds have been shown to be affected.

What are the signs?

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

vWD tests are important in the case of breeding programmes involving dogs 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 from vWD.  These breeds include Dobermanns, Scottish Terriers, Shetland Sheepdogs, Poodles, Pembroke Welsh Corgis, etc.

What are the initial tests?

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 (clotting) time are usually carried out.  A test also frequently carried out in the veterinary 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, to see whether vWD antigen is present or absent.

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, you are then prepared for the fact that a minor injury, such as a cut foot, could result in significant haemorrhage (bleeding) and in consequence have appropriate dressings available.  Similarly the information can be invaluable should any major surgery be necessary.

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 Willebrand's disease can lead perfectly normal lives.  Many drugs commonly used in veterinary treatment including pain killers (e.g. aspirin), antihistamines and some antibiotics are known to affect blood clotting.  If these drugs are used in a dog with vWD a major emergency is possible.

Please do not hesitate to contact us if we can help further.