# Von Willebrand's Disease -- New Research



## peppersb (Jun 5, 2011)

WOW. It seems that scientists at UC Davis have come up with evidence that vWD is not recessive. Previously it was thought to be recessive. For a recessive trait, breeders can be sure that the puppies will not have the disease if only one of a breeding pair is tested. But now they think that is it not recessive. 

Instead, it is a dominant trait with incomplete penetrance. Not all dogs that have the vWF mutation will present clinical signs of the disease. But some dogs with only one copy of the vWF mutation may be affected. Wow. That is a huge change in what the scientists are saying. 

Here's an image of the FB posting that I saw and a link to the UC Davis site for more info. Apparently UC Davis is sending this new info to everyone who ordered vWD tests through them.

https://www.vgl.ucdavis.edu/services/dog/vWD.php


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## spindledreams (Aug 7, 2012)

you beat me to it. It really is a HUGE change in status. Thank goodness mine are both clears...


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## zooeysmom (Jan 3, 2014)

Yikes! This is crazy! Maizie's sire is a carrier :ahhhhh:


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## peppersb (Jun 5, 2011)

zooeysmom said:


> Yikes! This is crazy! Maizie's sire is a carrier :ahhhhh:


My thoughts for what they are worth: If clear x carrier were producing affected puppies with any regularity at all, this would have come to light a very long time ago. Think about it -- it only takes one verified case of clear x carrier producing a poodle with vWD to totally disprove the theory that the vWD mutation is recessive. Responsible breeders have been breeding clear to carrier or clear to untested for a very long time. So why no problems until now? I can only assume that it is very unusual for a clear x carrier breeding to produce vWD. Or maybe the case of vWD that is produced is so mild that it does not get noticed. So frankly, I would not be worrying about Maizie. But these are just my thoughts -- I have no expertise in this field.

I posted the following on the FB genetics page. Reply from the original poster said that they are "trying to trying to get a hold of the study that this change is based upon so we can see what the frequency of affected is in those with one copy." Here are the questions that I posted on FB:

So here's my question about vWD. Breeders have been breeding clear poodles to untested poodles, or even to carriers for many years. If this is an unsafe practice that might produce puppies with vWD, then why has it taken so long for this to come to light? I would think that we would have seen cases of vWD from clear x carriers long before now. And that would have raised the alarm and disproved the theory that the vWD mutation is recessive long before now. So I really have three questions: (1) Why did it take so long for this to come to light? and (2) How much risk is there now for puppies from clear x carrier parents or from clear x untested parents? and (3) I assume that the recommendation is that carrier parents should not be bred. Is that true, or is there concern that removing carriers will further restrict the gene pool?

My guess is that we will be hearing more.


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## zooeysmom (Jan 3, 2014)

Thanks, peppersb, for helping me be rational about it. Gosh, can you imagine how restricted the gene pool would be if carriers were eliminated?


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## peppersb (Jun 5, 2011)

Here's some info from Natalie Tessier's web site. She's my favorite source for info on poodle testing and genetics. Interesting that vWD is now rare and that 96.5% of poodles tested for vWD were clear (and those stats are as of 2012 -- it may be an even higher percentage now). So maybe not a problem to eliminate carriers.

vWD (von Willebrand's) Type 1 is quite rare now in standard poodles because of the use of the DNA test, and if you produce an affected dog, it may have a negative quality of life. Type 1 vWD causes variable amounts of bleeding, since this diseases limits coagulation of blood, much like hemophilia. Authors disagree as to whether this is an autosomal recessive (needing two copies to cause the disease) or an autosomal dominant with incomplete penetrance (needing only one copy to cause the disease but the degree of illness varies from dog to dog). This is worth doing if a dog is being bred and a clear status by parentage cannot be shown in recent generations. If pedigrees are accurate and grandparents are tested and cleared, this test is not crucial. 

OFA stats: In 864 total evaluations through Dec 2012 of all poodles, 96.5% were normal, and .1% were abnormal, which most likely means 3.4% were carriers.

See more on Natalie's web site:

DNA tests & what they tell us - Poodles de Grenier


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