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OFA Hips OFA Elbows CERF OFA Thyroid OFA Cardiac von Willebrand's Bloat (GDV) Study Dog Owner's Reference

von Willebrand's

 

 

This is an actual copy of a von Willebrand's clearance from VetGen.  I am currently researching whatever it is that OFA offers for von Willebrand's in the form of a clearance.

 

 

 

 

 

 

 

 


**All italicized words in purple can be found in the Glossary on the main Dog Health page.**


What is Von Willebrand's disease?

Most basically,Von Willebrandís (abbreviated vWD) isnít so much a disease as a condition. Of all the inherited bleeding disorders in animals (and humans) it is the most common. The defect isnít autosomal (sex linked) so both males and females can suffer from the ďdisease.Ē It must be remembered that just because a dog doesnít show symptoms of von Willebrandís, it doesnít mean it canít be a carrier.

More specifically, von Willebrandís is an inherited bleeding disorder caused by lack of von Willebrand factor protein (abbreviated vWF). The vWF factor is a blood protein which binds platelets to blood vessels when they are injured. This protein circulates in the blood stream and must be present at the site of a blood vessel injury in order to control bleeding from that vessel. Absence or deficiency of the factor can, therefore, lead to uncontrolled bleeding episodes.

Certain breeds have a higher incidence of vWD than others. German Shepherds, Doberman Pinschers, Shetland Sheepdogs, Chesapeake Bay Retrievers, German Shorthaired Pointers, Golden Retrievers, Standard Poodles and Scottish Terriers all have a higher than normal incidence, indicating that it can be inherited.

What are the symptoms?

Excessive bleeding is the main symptom. Bleeding generally occurs after a wound or surgery. In these cases, the blood simply does not clot in the normal time, and bleeding is extensive. The most common signs of vWD are spontaneous bleeding from the gums or nose, blood in the urine or gastrointestinal tract (which may cause the stool to either have blood in it, or be black and tarry), or excessive bleeding at the time of surgery.  Bleeding into the joints may also occur, which can cause symptoms similar to those of arthritis. Other clinical signs include epistaxis, prolonged estrus or postpartum bleeding, hematuria, melena, excessive bleeding after toe-nail cutting and sometimes hemorrhaging into body cavities and organs.

How is vWD diagnosed?

The diagnosis of Von Willebrand's is made through a test which checks for the level of Von Willebrand's factor in the blood. To test their animals, owners simply take a sample of their dog's DNA by gently wiping VetGen-provided cheek swabs inside the dog's mouth, removing cells containing DNA. The swabs are then mailed to VetGen's laboratory and tested for vWD. After testing the sample, VetGen will send a summary of the results to owners.  The swipe from the cheek is a good sample because the cells that line the inside of a dog's cheek are continually being renewed, with new cells replacing the old ones. The cheek swab gently removes some of these old dead cells that contain perfect DNA samples for testing.

            Diagnosis can be performed by measurement of plasma concentrations of vWF. TESTING SHOULD BE DONE AT AN EARLY AGE SINCE THE DISORDER OFTEN DIMINISHES WITH AGE, CAUSING FALSE-NEGATIVE TEST RESULTS IN OLDER ANIMALS. Additional screening tests such as bleeding times or platelet agglutination assays can also be performed.

            The VetGen test is 100% accurate for vWD in Scottish Terriers but they do not list their accuracy for other breeds.  VetGen's vWD test is recognized by the Orthopedic Foundation for Animals (OFA). Additionally, the results of your dog's vWD test can be formally registered with the OFA. The VetGen Sample Collection Kit is only $5. The testing of the dog's DNA and the summary report of the results, cost $135 per- dog.

For further information call:
VetGen at 1-800-4VETGEN or go to their website at www.VetGen.com

 What are the risks?

These dogs, without treatment, can bleed to death following surgery, or what might be normally considered less than life threatening injuries. If your dog has shown any bleeding tendencies in the past or there is known vWB in the dogís family it is best to notify your veterinarian before any surgery or procedure.

What is the treatment?

Transfusions with blood collected from normal dogs is the only proven way to treat Von Willebrand's disease. Some dogs with Von Willebrand's disease also are hypothyroid - meaning they have lower than normal levels of thyroid hormone. Studies have shown low thyroid may raise the risk of bleeding complications in vVB dogs.  Veterinarians have found that thyroid supplementation can lower the tendency in some dogs to bleed while raising the level of vWF concentration. Some studies have been done which suggest a drug called desmopressin acetate (DDAVP) may help dogs with a bleeding episode. The drug can be administered intranasally (into the nose) to increase clotting. There is still some controversy over whether this treatment is effective.

There is no cure for Von Willebrand's disease but there are some precautions an owner can take to reduce the risks to their dog. Avoid drugs that are known to inhibit platelet functions. Aspirin is a prime example of one of these drugs. Others include antihistamines, sulfa- or penicillin based antibiotics, Ibuprofen, the tranquilizer phenothiazine, heparin and theophylline.  Prevention through eliminating affected individuals from any breeding program is the goal of veterinary medicine today. Tests are available to determine which dogs may have this trait. All individuals with a history of this disorder in their backgrounds should be tested.

Von Willebrandís disease isnít an automatic death sentence to dogs. Many of the dogs that have the condition will live normal lives with no complications. For those that do show clinical signs, there are usually options for the owner to guarantee the best quality of life the pet can have.

 

What are the genetic and heritability factors of vWB?

Different breeds exhibit different variations of the disease, and some individual animals appear to "acquire" vWD. While the bulk of the information available is based upon purebred dogs, the disease is not unknown in mixed breeds. The total number of breeds affected by vWF exceeds 50. The disease also appears in cats, pigs, horses, and humans.

There are three variants or forms of vWD (types 1,2,3) defined by the quantity and structure of plasma von Willebrand factor (abbreviated vWF) in affected dogs. Within each breed a single form of vWD predominates. Characteristic biochemical and clinical findings have been described in a number of breeds with high prevalence and/or severe forms of vWD.

Classification

vWF concentration

structure of vWF protein

Clinical Severity

Affected Breeds

Type 1

Low

Normal

Variable

Airedale, Akita, Bernese mountain dog, Dachshund, Doberman pinscher, German shepherd, Golden rertiever, Greyhound, Irish wolfhound, Manchester terrier, Schnauzer, Pembroke Welsh corgi, Poodle, Shetland sheepdog and others

Type 2

Low

Abnormal

Severe

German shorthaired pointer, German wirehaired pointer

Type 3

vWF markedly reduced or absent

Protein is absent

Severe

Familial: Chesapeake Bay retriever, Dutch Kooiker, Scottish terrier, Shetland Sheepdog

Sporadic: Blue heeler, Border collie, Bull terrier, Cocker spaniel, Labrador retriever, mixed breed, Pomeranian and others

         

Inheritance and expression patterns of vWD differ between breeds. All males and females have 2 vWF genes, one inherited from dam and one from sire. In many breeds, the presence of 1 abnormal vWF gene appears sufficient to cause abnormal bleeding in some (but not all) dogs. Dogs having 2 abnormal genes express the most severe forms of vWD.

Breeding recommendations use vWD diagnostic ranges as guidelines to reduce the prevalence of vWD within a family or line, without discriminating against all dogs in that line. Screening for vWD should help ensure that no severely affected puppies are produced.

Dogs that test in the normal range (vWF:Ag greater than 70%) are ideal for use in breeding programs. Matings between 2 vWD test-clear parents are predicted to produce only vWD clear pups. Progeny testing (testing parents and entire litter) is useful for confirming predicted genetic status based on a single vWF:Ag value. Progeny testing can help clarify the status of a borderline range parent.

In some cases, dogs that test in the vWD abnormal range (provided they do not express a bleeding tendency) may also be used for breeding. Carriers should be bred to test-clear, and ideally progeny test proven clear mates. Some puppies in these matings will test in the normal range. By increasing the number of clear to clear matings in subsequent generations, the proportion of vWD carriers in a line will be gradually reduced, without losing desirable traits. Carrier to carrier matings are undesirable, because these crosses are likely to produce the most severe form of vWD in offspring. Do not breed any dog that expresses abnormal or excessive hemorrhage.


OFA Hips OFA Elbows CERF OFA Thyroid OFA Cardiac von Willebrand's Bloat (GDV) Study Dog Owner's Reference