Curious as to how far back you look for and want echos done for breeding? The stud I am looking at has a echo clearance, but neither of his parents did. The parents were born in 2002 and 2003, so it's realistic they could have them, but also not.

TIA!

TVD was first diagnosed in the mid 1990's. Testing was expensive and not standardized (still isn't to some degree). I'm not sure how many breeders even bothered with testing back then. Not to mention, mode of inheritance was not clear.

As more research had been done, it has been generally accepted that the mode of inheritance is a dominant gene with incomplete penetrance. This means that it only takes one parent that has the gene for TVD to produce the disease. It also means that that parent may or may not be affected with the disease. I also feel there are other factors at play for the disease to be expressed. Therefore, it is virtually useless to try to breed away from TVD by making sure previous generations are clear for the expression of the disease. Until we find the actual gene, the best we can do is test our own dogs and not breed dogs that express the gene. I've seen pedigrees of affected dogs that were clear for generations. A dog that has the gene for TVD that does not express it (clear echo) can stay hidden until an affected dog is routinely tested. I bet there are a fair number of pet Labs that are affected, but in its mildest form will never cause a problem to the dog nor will ever show symptoms related to the disease.

So don't fool yourself, generations of clear does not guarantee nor reduce your chances of producing TVD.

I know TVD can appear anywhere, I just was curious if there was an advised "protocol". Thanks for the bit of history too, we don't learn unless we ask the question and others share. Just trying to do the best I can, as we all should be doing. :)

Yes, but doing all the screening we've done over the last 20-25 years really hasn't reduced the occurance of the disease. It's really not that common, just mainly in certain lines. It's getting harder and harder to avoid them, but I don't believe that TVD is on the rise, even in those lines. We just know it's there, screen for the expression and not use those that are showing it through an echo. It's also not an automatic death sentence for the dog either. The number of dogs that I've known to have had the expression of the disease usually live long, normal lives. I think we've had it in the breed a long time and advances in technology allowed us to find and then hysteria took over, just as it did with the PRA scares of the 1980s. Thankfully we got a test for that and hopefully we'll get a test for TVD and epilepsy in the near future.

They always said the longer you've been in the breed you will eventually produce nearly everything. I've been lucky to not have produced PRA and won't now that we have a test, but I have pretty much produced just about everything else that afflicts Labradors over the years. And that's just dog breeding.