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Permalink Reply by Beth on January 9, 2012 at 10:39pm

By the way, about half of all Cavs get MVD by age 5, all by age 10.

Around 6 in 10 Goldens gets cancer before it reaches the previous longevity of the breed.

THOSE are breeds with serious, serious health problems.

I think something like 1% of Pems get DM.   Do I want to trade off that 1% for what so many other breeds have?  We have a neighbor with a ten-year-old Golden whose breast cancer metastasized to her brain.  She has seizures and will attack them while seizing.   There are lots and lots of genetic diseases in dogs. Aggressively breeding away from one can land you with another, much worse one.

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Permalink Reply by Melissa and Franklin! on January 10, 2012 at 12:48am

Beth, 

Working at a vet and seeing the results of bad breeding, and having had a german shepherd with DM, I totally and completely support your argument. I used to work with a cardiologist, and we had more cavaliers than I can count come in due to heart problems, I have had several people involved with the breed tell me 9 out of 10 cavaliers will have heart problems. As you pointed out boxers with cancer, and boxers also have horrible heart problems, Lets not forget the bernese mountain dogs where age 7 is considered ancient, they get histosarcomas that kill them within weeks of onset of first symptoms, having lived their whole lives suffering from debilitating hip and elbow dysplasia. And what about the mess we have made of German Shepherds? I won't even touch that genetic nightmare. OFA is only dogs in America correct? I wonder what DM stats are for corgis worldwide? Do you think it is less/more/or the same percentage of clear/at-risk/carrier? My first german shepherd had DM, she was 11 when we had to put her to sleep, not because of the DM, but because of cancer. I agree with Beth, I'd much rather have a dog with a disease that doesn't begin to show up until age 8-14 years, than have my dog die at 4 years old because of cancer. Nobody wants a dog with DM, and we all want to do our best to try to get rid of it in the population, but breeding ONLY DM clear dogs is not the answer. It needs to be a very slow, multi-generational effort or we will end up opening a whole other can of worms that may be much worse than a disease that effects 1% elderly animals in the breed.

There was a really awesome program on National Geographic about dogs and part of it they had a population of foxes that the Soviet Union and Russia had been conducting breeding studies on for over 50 years (the research continues today). The part of the experiment that was on this program was showing how physiologically and morphologically different these foxes became when breeding for one specific trait. In this case they were breeding for friendliness. This species was naturally very aggressive,a  black lanky animal that looked more like a cat than a fox. After I believe it was 10 generations of breeding JUST for this friendliness they had created a dog like creature that was now white instead of pure black, had a thick fluffy tail that was beginning to curl at the end, and the animal was much stockier than its ancestors. It is just an example of the changes one can make in a species (or breed) by just focusing on ONE trait. I would hate to see corgis that were white with floppy ears and long legs just because we were breeding only DM clear dogs. Also, as is clear by this discussion, we just don't know enough about DM or the genetics behind it to support totally culling 91% of the gene pool. 

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Permalink Reply by Megan C on January 10, 2012 at 2:28am

It is not 91% of the gene pool... you would still use carriers for breeding.  DM is a fault just like hips, cosmetic issues, and wonky conformation.  No one suggests that not using a dog that has weird confo  for breeding is a horrible idea.  DM is just not outwardly visible until the dogs are older and out of the show ring.   And we already use very little of the gene pool.  In every litter of 4-9 puppies maybe 1 or 2 are ever used for breeding.  Breeding away from a known genetic disease does not mean all sorts of others will suddenly crop up.  You could make that argument about any trait. "If we start breeding away from fluffs then we will wind up with issues just like these other breeds."  Those other breeds have gotten into dire straights due to breeders not actively working toward breeding away from health problems To quote Wiki for the Cavaliers and their heart disease:  The chairperson of the UK CKCS Club has said that "There are many members who are still not prepared to health check their breeding stock, and of those who do, it would appear that many would not hesitate to breed from affected animals."^[32] The MVD breeding protocol recommends that parents should be at least 2.5 years old and heart clear, and their parents (i.e., the puppy's grandparents) should be heart clear until age 5.^[33]  

And Arabs are crazy not because they chose to breed away from SCID, they are crazy because the top show barns want them that way so they stand and trot looking bug-eyed and snorting with their knees trotting up to their eyeballs.  The older less-popular lines are much more sensible but they do not show well on the breed circuit.  

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Permalink Reply by Beth on January 10, 2012 at 7:11am

First, I never said you suggested we cull 91% from the gene pool.  I did say that what you are asking is we breed that 91% to only the other 9%, meaning that same 9% of dogs would show up in the first generation of EVERY corgi born this year if we follow your suggestion.   And here's the thing:  you make it sound like the 9% are perfectly healthy and the other ones might get DM, but we don't know that.  What if we find out (too late) that the 9% are more prone to IVDD, which tends to strike YOUNG dogs and also ends up with a paralyzed dog in severe cases?  What if the 9% had worse hips and how HD is common instead of rare?  What if the 9% have an average lifespan of 10 instead of the 12 to 14 now common?  And instead of a breed where most live to 12 to 14 and a tiny handful get sick at around 10 and are gone by 13 from this disease, they are now all dead at 10 anyway?  Would that help?

Over 50% of Corgis are At Risk for DM, yet something like 1% or so get it.  Let's say 1.5% to be generous.  That means that 97% of At Risk Corgis won't get clinical DM in their lifetimes.  Why is that?  We don't know.  They are right now in the middle of a study looking for modifier genes, so let's wait to see what that finds because we might be throwing out a whole lot of healthy genetic material for nothing if we breed aggressively away from it and find out it's not just Gene A, but Gene A + Gene X + Gene 789 that is the real problem.   This is from that study, which I linked to earlier: "The availability of the DM test has raised questions that must be answered before the test can be used by dog breeders."

To answer your other questions:  things like vWD are bred away from because a dog with two copies of that gene mutation WILL have vWD.  It's not like DM where most with the double mutation WON'T get DM.  

Some breeders still use fluffs in their programs;  some will breed two fluff carriers to each other.  However, if fluffs made up over half the population, obviously we'd see a lot more fluffs being bred and the breed standard would reflect that.

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Permalink Reply by Beth on January 10, 2012 at 10:18am

Melissa, thanks for your insight on other breeds.   Corgis are actually one of the healthier breeds out there.  Many Corgis live into their early teens. 

 

It's interesting that the thought is that cancer in Goldens goes back to the original founders, since it's prevalent across all lines (show, backyard breeders, working dogs, etc).   I never realized until recently that many purebreds trace back to just one or two founding dogs as fanciers tried to recreate breeds after the wars in Europe, or developed new breeds based on just a few dogs.

 

The other way genetic diseases get into lines is when people breed heavily towards one set of traints, be they behavioral (good noses) or structural (a certain topline) or cosmetic (a color).   Or diseases can crop up based on popular sire syndrome, where a small handful of popular studs ends up in everyone's lines and then they find out years later that they were carrying something, or there is a recessive gene that suddenly becomes obvious because it becomes common.

 

There are times when something gets in by chance (the cancer in Goldens may have not been linked at all to genes for color or type, but it just so happened that the founders were predisposed to cancer).    There are other times when it is linked to desired traits and can't be removed without changing the breed (the gene for longevity seems to be inversely tied to the genes that govern size, for instance, and most giant breeds have short life spans). 

 

Your example of the foxes is fascinating.  For instance, is the curled tail tied to the gene for friendliness?  OR is it random, and they happened to occur together in this population of foxes, but if you started over with an unrelated population you might end up with, say, all the friendly foxes being bobtails instead?    If EVERY time you repeat the experiment you end with curly tails, then it would indicate they run together and breeding for a different tail would likely impact friendliness.  If every time you repeat the experiment you get a different tail set, it would indicate they are not linked and you can safely breed away from tail without impacting friendliness.

 

Genetics is really in its infancy.  I donated blood for a genetic study for a disease I have, and they are up to about a dozen genes that they believe influence the course of the disease.   My guess is we will find something similar with DM, and the money will come in because it's so closely related to ALS.

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Permalink Reply by Caitlin Randolph on February 5, 2014 at 1:17am

I am so grateful for this website. Started on it feeling absolutely fearful of DM prospects and left it feeling like I shouldn't worry and now wondering if Arrow's curled tail is why he is just so darn friendly. I always say he looks like a fox with that tail. Maybe that friendly fox was bred into a low sturdy animal with a curled tail named Arrow!! Some say Pem's are friendlier/less shy than cardi could this be because Pem's tend to have the curled tail (when undocked) are the Pem's with the straighter tail like the cardi less social!?

Fascinating. And finally a happier train of thought. Than a scary DM risk.

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