Von Willebrand's Disease, Canine - contd.
Von Willebrand's disease refers to a bleeding disorder that results from reduced concentrations of a specific protein called von Willebrand's factor. This substance plays a key role in the adherence of platelets, the cells that normally help blood clot, to collagen, a protein exposed by injury to blood vessels. Dogs with von Willebrand's disease may bleed spontaneously, most frequently from the nose, the mouth, and the urinary tract. More frequently, affected dogs bleed only when there is a stimulus for bleeding, such as an injury or surgery. Von Willebrand's disease can be a frustrating condition to diagnose, manage, and prevent because not all dogs with low concentrations of von Willebrand's factor have symptoms related to the disease.
Von Willebrand's disease is often classified according to the type and presence of different components of the von Willebrand's factor, called multimers. In type I von Willebrand's disease, all the different multimers are present, but in concentrations that are below normal. This type is the most common form of the disease and is characterized by bleeding from the mouth, nose, and urinary tract. Although spontaneous bleeding may not occur, excessive hemorrhage may be seen during elective procedures such as dentistries, ear cropping or tail docking, spaying, and castration. Breeds affected with Type I von Willebrand's disease include the Doberman pinscher, Airedale, Shetland sheepdog, and Pembroke Welsh corgi.
With type II von Willebrand's disease, smaller multimers are present, and there is a lack of the larger multimers, which are more important in the clotting process. This is a relatively uncommon form of the disease, but can result in severe bleeding episodes. German shorthaired pointers are most commonly affected.
Type III von Willebrand's disease is the most severe form. Animals with this type of the illness lack any measurable von Willebrand's factor and as a result, they can experience severe blood loss. The breeds most commonly diagnosed with this form of the disease are Scottish terriers and Chesapeake Bay retrievers.
