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Permalink Reply by Beth on October 10, 2009 at 8:38am

vWD is recessive which means if the sire is clear, the dam does not need to be tested. You need two copies of the gene for the disorder to present. You cannot get a copy from a clear, therefore these pups are not at risk for vWD. The worst they could be is carriers, and being a carrier is not a health risk. I have a female who is vWD carrier and was bred once before I got her; because she was a carrier, she needed to be bred to a clear but she has no medical issues as a result.

Because of the newness and complexity of the DM test, many (I dare say most) are still not testing and/or testing but not announcing. Preliminary results show a huge percent of Corgis test as at-risk or carrier for DM, making potential clears to breed to hard to find, and the vast majority of dogs who are at-risk do not seem to develop the disease. It is also recessive, but there is great speculation at what the "trigger" is that causes some at-risk dogs to get the disease, but not others. It may be an environmental trigger, but currently they are looking for modifier genes as the more likely issue. You should be able to have an honest conversation with the breeder about your concerns, but as I said many good breeders are not testing. If it were me, I would not hesitate to buy from a breeder who isn't testing, with all the unknowns. There are a few posters here who are adamant that every breeder should be testing and sharing results, and they may post in the thread. Ultimately the decision is yours, but keep in mind that if you are requiring the test it may greatly limit your pool of potential breeders.

DNA testing can be done at any age, as far as I know. The vWD test would be unnecessary, as your clear sire ensures your pup will be at most a carrier. It is only advised if you plan on breeding (and if your breeder knew she was already planning a breeding to a clear, she can in good conscience skip that test, but would need to test if she was breeding to a carrier). Since DM is relatively uncommon, only affecting a few percent of Corgis and mostly in old age, honestly I would only test personally if my dog was showing symptoms and they were trying to determine if it was likely DM, or IVDD, or something else. But again, that decision is yours.

Oh, and some breeders will say "vWD clear by parentage" which means both parents were tested clears so there is no chance of the pups being anything but clear.

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Permalink Reply by Beth on October 10, 2009 at 8:47am

Here is a link to OFA's results of testing.

http://www.offa.org/dnateststats.html

As you can see, only 655 Pems have been "officially" tested, and only 7% of those are clear, hence the hesitation in testing as it appears there is very limited good you can do with the results to actually ensure a clear.

And this is OFA's recommendations, for what it's worth:

http://www.offa.org/dnatesting/dmbreederguide.html

And here's the website regarding a lot of the ongoing study:

http://www.caninegeneticdiseases.net/DM/ancmntDM.htm

We each must make our own decision of what to make of the info, as it's all quite new (the test is only a bit over a year old).

Good luck!

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Permalink Reply by John Wolff on October 10, 2009 at 10:29pm

There are several DM threads on here.
I have the original DM paper. They did not explicitly state a gene frequency for the at-risk "AA" genotype, but I believe it was about 2/3 of their presumably random control group among PWC. So testing for DM won't tell you much. If I've got it right, your dog is probably AA at-risk and probably won't get DM.
I think the test is mostly good for screening breeders.

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Permalink Reply by Amy & Peggy on November 9, 2009 at 2:17am

Thanks to both of you for the information--very helpful indeed!

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