Friday 7 November 2014

Von Willibrand's Disease (VWD) (Also known as Canine Haemophilia)

Background information
Haemophilia is a bleeding disorder of varying severity that is due to a deficiency in specific clotting factors. Normally the body responds to an injury that causes bleeding through a complex defence system, whereby the blood clots to prevent excessive bleeding, however dogs affected by VWD don’t have this defence system and can ultimately bleed to death from a relatively minor cut.

Haemophilia is an X linked, recessive disorder. It is one of the few sex-linked traits in dogs. Because males have only 1 X chromosome, a male dog is either affected or clear of the defect. Females, with 2 X chromosomes, may be affected (abnormal gene on both chromosomes), clear, or a carrier with no clinical signs (one gene affected). In effect, the disease is carried by females but affects mostly males.

The disease occurs in many different breeds and in mixed breed dogs as well. The German shepherd is the breed most commonly affected.

Dogs with mild forms of haemophilia may experience few or no signs, and may never require treatment until/unless surgery or trauma is followed by excessive bleeding.

Where haemophilia is more severe, you may see signs of a problem at a fairly early age. Your pup may have prolonged bleeding associated with the loss of baby teeth, or unexplained areas of bleeding/bruising under the skin. Bleeding into muscles or joints will often cause lameness.

Once the condition is diagnosed, your veterinarian will discuss ways to manage this lifelong problem. These include being alert for signs of bleeding episodes in your dog, and tips on housing and maintenance so as to minimize risks of bleeding. Periodic blood transfusions will generally be required.

Unfortunately, dogs with severe haemophilia often die or are euthanized because of recurrent or uncontrollable bleeding problems.


Diagnosis

The clinical signs associated with haemophilia vary widely, based on the severity of the bleeding disorder and where in the body the bleeding occurs. Because this is a sex-linked disorder, dogs with haemophilia are almost always male. Affected dogs are commonly brought to the veterinarian for problems such as bloody diarrhoea that is difficult to control, areas of bleeding under the skin, or lameness (due to bleeding into muscles or joints).

Once a bleeding disorder is suspected, specialized laboratory tests are carried out to diagnose the specific disorder. If your pup is diagnosed with haemophilia, it is important that you inform the breeder so that he or she can have your dog's parents tested. (The mother is likely a carrier and the father free of the defect).

Treatment
There is no cure for this disorder. Mildly affected dogs may never require treatment, or only after surgery or trauma.

With more severe haemophilia, your dog will require periodic transfusions when bleeding occurs, to replace the deficient coagulation factor activity. Strict cage rest is important along with transfusion, to decrease further haemorrhage.

Information obtained from The Utonagan Society

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