Hello,
Does anyone have experience with a DM Corgi? Rosie is 11-1/2 and was diagnosed last summer. She's losing more function in her rear legs and is learning to use her wheel cart. She's not thrilled with it but she goes along, and I think she realizes that she can go for walks with us if she's in the cart, but must stay home if she's not. I participate in the Yahoo group Wheelcorgis which has been wonderfully helpful. Are more breeders testing for DM?
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From what I understand about DM testing, between 75 and 80% of corgis test At-Risk for DM. A good amount of those don't ever come down with DM, some come down fast, some come down very slow. My breeder tests for DM and most of her dogs test positive. She has one dog going down with it now-- it started in October or November, and now she's lost all use of her hindquarters. My breeder suspected she would be gone by now, but she's still here! My breeder is also CONVINCED that good diet is key to slowing or even preventing DM from happening at all, along with a myriad of other diseases.
More breeders can test for DM, but removing dogs that test At-Risk from the gene pool introduces a whole host of new problems. Also, At-Risk dogs don't get DM for sure, so there's no real reason (as of yet) to do so.
I am sorry to hear about your Rosie but glad she's learning to use her cart. I can't offer any info on caring for a DM dog, but there are some other groups out there that someone might direct you to.
As far as breeding, I think a lot of breeders are being extremely cautious about testing. According to OFA,
http://www.offa.org/stats_dna.html?test=DM
52% of Corgis are "At Risk", meaning they carry two copies of the gene and can potentially come down with DM. Yet only a tiny single-digit percent of Corgis ever get DM, which means there is more going on than just this gene.
39% of tested Corgis are Carriers (one copy of gene).
Only 9% of tested Corgis are Clear.
Breeding all Carriers or At-Risks to that 9% that is clear would devastate the breed and could create a monster, with some other disease showing up that is much more prevalent or strikes young dogs down.
Even breeding just to the 39% Carriers would wipe out more than half the gene pool. I think most are proceeding cautiously until there is more info.
Here's a good article on what can happen if breeders are very aggressive in getting rid of a disease that is wide-spread:
http://www.akcchf.org/canine-health/your-dogs-health/when-good-dogs...
It's also difficult to sell puppies when you say "5 of these pups are at risk and 3 are carriers. I'm keeping 2 carriers for my program, so here is your at-risk puppy!" So it's quite possible breeders are watching and acting but keeping results to themselves. Not being a breeder, I can't know for sure, but the last one I asked about it said their approach was to see what further research showed about possible modifier genes or environmental factors.
Good luck with your girl. She reminds me of my Madison. I hope you get some good advice on support groups out there.
There are several DM threads on this site. I take an interest in this because I'm a research tech in a medical genetics lab that works on human inherited neurologic diseases. DM in canines is caused by/linked to a mutation in the SOD1 gene which causes ALS (Lou Gehrig's Disease) in humans. It is progressive and invariably fatal. Check out Wendt Worth Corgis (recent DM clear litter) and Kathleen Mallery, both on this site. I'm sure there are others.
It's not simple. Because ~66% of pems are at-risk (AA) and very few are clear (GG) -- the A allele frequency is about 75% in Pems -- it's not a simple matter of breeding only clear dogs. This could create a genetic bottleneck and create unintended consequences, further inbreeding, and lose a lot of valuable corgi genetic material. Review your high school biology -- Punnett squares and crossovers, wiki it -- and you'll see how breeders can breed GG to AA or AG dogs and get no affected pups -- AG x AG should yield about only 25% AA at-risk pups, and this might be worth risking in some cases to preserve valuable genetic material. I'm guessing that some valuable corgi traits may be tightly linked (close on the chromosome to) that A allele, which is why it's so frequent (this is a guess, may be wrong). Breeders might get lucky and eventually de-link the valuable corgi traits from the A allele -- eventually, there will be crossovers between the A allele and whatever corgi traits we want to preserve.
So don't necessarily insist on breeders who breed only GG clear dogs, but do look for breeders who are aware and knowledgeable and testing and have a coherent strategy for weeding out the A allele without losing all the valuable genetic material that's currently linked to it. If only one parent is GG clear, no pups should be AA at-risk.
I'm always touched by a corgi on wheels -- it shows so much love at a glance -- Rosie looks like Gwynnie.
John, one of the videos I saw had the researcher suggesting that because genetic prevalence is so high, what might be a reasonable goal now is that breeders who have had DM dogs (as opposed to DM genetics) in their lines might start trying to breed towards carriers and away from At Risk, but those that don't have DM showing up in their lines might take a more conservative approach to protect genetic diversity. At least that's how I recall.
Yeah that's basically what I was trying to say. There may be some unknown modifier genes out there that are preventing some AA dogs from developing DM. Remember that this scince/technology is still in its infancy and we don't know the whole story.
Got a link to that video?
I have experienced DM first hand with my late corgi.
There is another group on yahoo
http://pets.groups.yahoo.com/group/degenerativemyelopathylist/ that I like. If you ever want someone to chat with please feel free to contact me! :)
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