To be copied only with permission of Vandra Huber
(from an email by Vandra Huber)
vonWillebrand's Disease = VWD
==========================
Canine von Willebrand's Disease
-------------------------------
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 Hound, Dachshund (mini & std), German Wirehaired Pointer, German
Shepherd, Keeshond, Manchester Terrier (std & toy), Miniature Schnauzer, and
Rottweiler.
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 Spaniel, German Shorthaired Pointer, and German Wirehaired
Pointer.
Type III vWD is essentially the complete absence of vWF. Severe type III
vWD has been diagnosed in Australian Cattle Dog, Chesapeake Bay
Retriever, Fox Terrier (toy), German Shepherd, Scottish Terrier, and Shetland
Sheepdog.
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. Personal experience demonstrates this.
Our Scottie tested as a severe type III (0% vWF). He is eight months
old,
and his history is apparently not atypical. At about 3-4 months, over a
period of about ten days, he routinely lost all of his deciduous teeth.
The bleeding in each case stopped within minutes. One day later, he
developed a bleed at the inside of one of his permanent teeth - between the tooth
and the gum. It continued for four days. We had him transfused (from his
mother), and the bleeding eventually stopped. Since then - about four
months ago - he has experienced five more bleeding episodes. The first two were
similar to the original one, in the same relative area of the mouth, and
both were stopped by cauterizing with silver nitrate. The third was an
injury - a small cut on his lower lip, probably from a bramble bush -
and it too was stopped by cauterization with silver nitrate. The fourth was
also an injury - a tongue puncture from banging heads with his mother. It
stopped of its own accord within ten minutes. The last was a very small bleed from
one nostril which stopped by itself within about five minutes.
As you can see, living with one of these affected animals can get quite
interesting. We cope by being 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. We play with him as we would any other dog, and he is as spirited as an
unneutered male Scottie can be (which is VERY spirited).
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. I would recommend having a dog tested prior to paying for it - especially
if it belongs to one of the high risk breeds. It is the only way I know of
to avoid the heartache later. 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.
Dr. Cloutier -
I am not suggesting that all the puppies with genetic problems be killed, just don't breed them.
Good point, and one I am personally committed to helping see become a reality.
Discussions at the moment are particularly interesting re Scottish Terriers
and Type III vWD. Now that there is a genetic test for the discovered
causal gene mutation (being verified as we speak - I will be testing Kramer and
five of his relatives this weekend as part of the verification study), I
find that the issue of breeding carriers has become somewhat different
than it was before. Assuming - and it is a BIG assumption that may not pan out - that all
puppies are tested, the idea of breeding carriers to clears to
perpetuate good traits becomes more viable. All other carriers would be spayed or
neutered. While I tend to want to take the draconian position of never
breeding ANY carriers, this does seem like a workable compromise that
could turn the vWD situation around in Scots. At least it will be possible to ensure
that no affecteds are ever created, which is the most important issue. Unfortunately,
this is only a fraction of the issue re vWD, but it IS a start, and a good one.
Obviously this idea only works when a definitive test, such as we are
all hoping this one proves to be, is available.
---------------------------------
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.
-----------------------------------------------------------------------
** Gary Mason - Research Manager Interleaf, Inc. Waltham, MA **
** gmason@ileaf.com 617/290-4990 X2100 FAX:617/290-4966 **
========================================================================
Update: The DNA test for VWD has indeed become a reality for Scottish Terriers
and for several other breeds. Within months of the test becoming available few scotties
were standing at public stud which had not been tested and most carriers were removed from
public stud. VWD is basically a disease of the past in Scotties. The disease had actually
affected a much smaller percentage of the population than originally believed. In order for
the researchers to find the gene in another breed they require cheek swabs from affected
animals. If you unfortunately have a VWD dog, turn it into something positive by contacting
the researchers at VetGen and doing something to find the DNA test for your breed.
