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53 von Willebrand's Disease




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This article is from the Canine Medical Information FAQ, by Cindy Tittle Moore with numerous contributions by others.

53 von Willebrand's Disease

_Contributed by Gary Mason_

Von Willebrand's disease (vWD) is an inherited bleeding disorder. It
is a complex and difficult disorder to deal with, because genetics,
diagnostic abnormalities, pathogenic mechanisms, and sometimes
conflicting clinical signs are all involved. The commonality between
all vWD is a reduction in the amount or function of von Willebrand
factor (vWF), which is manifested through abnormal platelet function
and prolonged bleeding time. 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.

Human variants of vWD are broken into three main types which can be
used to describe canine vWD. Type I vWD is characterized by a low
concentration of normally structured protein. In screening studies
done at Cornell over a period of years (1982-1992), percentages of
dogs of some breeds tested as carrying the disease, and with
concentrations of vWF less than 50% of standard (considered to be at
risk) were:

        Breed                   Total # Tested          Average % Affected
                                (through 1/93)          1982-87    1988-92
        -----                   --------------          ------------------
        Corgi                         3726                   29         42
        Poodle (std & min)            4048                   17         29
        Scottie                       6505                   14         30
        Golden Retriever              6906                   14         27
        Doberman                     22255                   64         74
        Sheltie                       9393                   22         34
        Akita *                        981                    0         27
        Cairn **                       411                    0         23

* Totals for years 1989-1992.
** Totals for years 1990-1992.
All others for years 1988-1992.

Other breeds with a known prevalence of vWD in excess of 15% include
Basset Hounds, Dachshunds (mini & std), German Wirehaired Pointers,
German Shepherds, Keeshonds, Manchester Terriers (std & toy),
Miniature Schnauzers, and Rottweilers.

Type II vWD is characterized by a low concentration of an abnormal
vWF. Breeds in which severe type II-like vWD has been diagnosed
include American Cocker Spaniels, German Shorthaired Pointers, and
German Wirehaired Pointers.

Type III vWD is essentially the complete absence of vWF. Severe type
III vWD has been diagnosed in Australian Cattle Dogs, Chesapeake Bay
Retrievers, Fox Terriers (toy), German Shepherds, Scottish Terriers,
and Shetland Sheepdogs.

In vWD dogs, bleeding can be spontaneous - usually from the mucosa of
the mouth, nose, or gastro-intestinal tract. Injury that is
accompanied by bleeding may continue unabated until a transfusion is
administered. Whether or not bleeding from small wounds will stop
without treatment is not predictable.

Living with one of these affected animals can get quite interesting.
You must be careful with him in the house; by always having him on a
leash or within our sight in a portable pen when outside; and by
having a unit of frozen plasma at the veterinarian's at all times.
Obviously, elective surgery is not advised. Required surgery can be
preceded by transfusion with good results, though you can never be
certain.

Lastly, most of these diseases can be stopped by testing before
breeding, and through selective breeding. Unfortunately, experience
and hearsay indicate that the AKC is not active in the enforcement of
these preventive measures. Apparently the breeders, at least some of
them, are not either. You should insist that the parents of a litter
in a high risk breed have been checked prior to breeding -- and that
the puppies have likewise been tested.

There is a definitive genetic test for Type III vWD in Scottish
Terriers. The non-invasive test is available from VetGen
(800-4-VETGEN).

For other breeds, test kits and instructions for vWD are available
from:

Comparative Hematology Section - Diagnostic Laboratory
College of Veterinary Medicine, Cornell University
P. O. Box 5786
Ithaca, NY 14852-5786

607/253-3900 Voice
607/253-3943 FAX

These folks are very concerned and cooperative. I have exchanged
several Emails and phone calls with them. They are interested in the
dog's history, and are happy to hear anecdotal information - it is
just one more piece to the puzzle. They also maintain a (large) kennel
for affected dogs, so that might be an alternative if you can't keep
one, but don't want to put it down.

_NOTE: Most of the information above has been gleaned from data and
information developed at, and published by, the New York State
Department of Health Hematology Laboratory. _

Additional Comments

The "traditional" vWD test (non DNA based) has enormous problems with
accuracy and determination of precise vWD status. The blood collection
for the vWD test must be done very carefully: you can only extract
blood once, and you must not shake or separate the blood. If the test
is done consistently and very carefully it can be useful. However, it
is difficult to diagnose vWD without the test as there are many other
things that can cause a bleeding problem, such as warfarin (rat
poison) poisoning. So you might see non vWD dogs bleeding to death
that are kept in a rat infested environment, for example.

Homozygous dogs rarely survive puppyhood. Heterozygous dogs generally
have clotting problems (taking longer to stop bleeding and form a
scab) which generally show up when the dog's tail is docked, dew claws
are removed, or other surgery is done in which the problem becomes
apparent.


 

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