Hello,  sorry haven't been on here for years, but just wanted to say that my darling lab who was nearly 13 yrs old has just had to be sent to rainbow bridge because of this awful condition.
We bred 9 pups from her 9 years ago and am worried that it is genetic.  I know that all the pups are now fairly old, but this is not a usual condition for a labrador is it?  I am still in touch with all the pups owners so want to be able to warn them and give them some advice.
It was horrific how quickly it progressed and wouldn't wish it on anyone.
I also still have her son, and am constantly looking for clues that maybe we missed with Sasha.
Does anyone here have any experience with this awful disease?

Lynds30. DM:  I am so sorry for your loss -I too have lost a fantastic girl to Rainbow Bridge just 8 weeks ago It is such an horrific thing and yes unfortunately it is a known condition in Labradors however, if the Sire was free of this genetic condition then an educated estimate is that at the most 50% of the Puppies born would be affected - if at all & 9 years is a long time ago?  Mother nature always has the last say.  Sasha's son is his own person so please don't spend lots of time judging his tomorrow - enjoy him for the day

if the Sire was free of this genetic condition then an educated estimate is that at the most 50% of the Puppies born would be affected

If dam was affected and sire clear, then 100% of the pups will be carriers but none can be affected.

There is a DNA test for it, you have exon 1 and exon 2. If you go onto Laboklin you can find the test, I think its exon 2 you need to look at which is all breeds.
To have affecteds then either one parent was a affected and the other a carrier, both affected or both carriers.
Your bitch was affected. There is not a lot you can do now unless any of the offspring were bred on?
Sadly there is no cure for it but there are plenty of groups on fb and online for advice.
Is the sire still alive? If so see if they will test for it, even offer to pay for it. If he is clear then at worse all offspring will be carriers which means they won't develop it

Can somebody tell me via Mendels Theory, the percentage of offspring when one parent is affected and the other carrier?   I have the other percentages but not that one, for some reason.  Thanks.

To OP, sorry for your loss of course.

https://www.fitzpatrickreferrals.co.uk/neurology/canine-degenerative-myelopathy/

Half carrier,  Half affected.

The carrier parent can pass on either a normal gene or a faulty gene.

The other parent can only pass on abnormal genes.

This isvfor Autosomal recessive traits.

> Half carrier,  Half affected.

Each puppy has a 50% chance of being a carrier and a 50% chance of being affected.

The status of each puppy is an independent event (like the toss of a coin) and therefore it is entirely possible, although unlikely in a large litter, that the litter could contain all affected or all carrier puppies.

Whilst half carrier and half affected is the most likely overall outcome for the litter it is incorrect to state half will be affected and half will be a carriers.

Agreed, the question was the theoretical statistical probability.

Just like sex ratio in litters being 50% of each, we know it doesn't work like that in individual litters.

I bred a litter of 8 in 2011, only to discover 4 years later that I had inadvertently mated 2 Carriers of Open Angle Glaucoma, when a DNA test became available.

I contacted all the owners suggesting they DNA test so that should their dog have inherited 2 faulty copies of the gene they could monitor their dogs intra ocular pressure regularly, and save their sight by timely use of medication.

By the time symptoms occur in my breed it is usually too late. It is late onset, normally at 6+ years.

Sadly 4 prefered not to know.

The 4 tested came back 3 Clear and 1 Carrier, where statistically you would expect 2 Clear, 2 Affected and 4 Carriers.

They are now coming up to 10 years, so hoping we have been lucky. In our breed it turns out that not all genetically affected go on to get disease symptoms, there appears to be some unknown trigger needed.

Goldmali: DM perecentage of puppies affected or carriers:  We can go through all the percentages/figures/estimated guesses etc and no one seems to know for sure.  The only thing that is sure is that there is a genetic issue here.  I believe that's what the OP was looking to confirm.  No guarantees can be given and a simple probability at the end of the day is was all that was required IMO.  I believe general questions just need a yes/no or indifferent.  Many responses come from very knowledgable people such as yourselves which is fantastic but reassurance and ongoing advice is probably their reason for asking - apologies but scientific explanation can be over whelming for many.

Hoggie I don't think you understand how this works. There is no guess work just probabilities. Your initial statement was just plain wrong and Goldmali simply corrected you.

The simple way to get an absolute answer as to whether any of the puppies are affected by this condition is by getting them tested.

Failing that here are some probabilities. If we assume the figures in this article for the prevalance of DM in labradors is correct

https://www.pawprintgenetics.com/blog/2015/03/09/degenerative-myelopathy-and-centronuclear-myopathy-labrador-retriever/

"In one study of 475 Labradors, 4% were non-symptomatic carriers of the mutation and 4.8% were at-risk of developing disease due to the inheritance of two copies of the mutation"

So we have -

The sire is affected and the dam has a 91.2% chance of being clear so there is a 91.2% chance that all puppies are fine.
The sire is affected and the dam has a 4.8% chance of being affected so there is a 4.8% chance that every puppy will be affected.

The sire is affected and the dam has a 4% chance of being a carrier so there is a 4% chance that some of the puppies may be affected.
In a this scenario there is a 50% chance of any one puppy not being affected or not. So in a litter of 9 puppies there is a 0.2% chance of all 9 puppies being clear and a 99.8% chance of at least one puppy being affected (0.2% chance of all puppies being affected) and 0.2% of 4% is so small it is not worth worrying about.

So the overall liklihood remains as follows

91.2% chance all puppies are fine
4.8% chance all puppies are affected
4% chance some puppies are affected

Or perhaps more simply put there is roughly a 1 in 11 chance at least one puppy from the litter is affected.

We can go through all the percentages/figures/estimated guesses etc and no one seems to know for sure.

Without knowing, by DNA testing, whether a dog is affected, a carrier or clear, we don't know anything. But your scenario was basic genetics for any recessive condition; one affected parent mated to a clear parent (clear means not affected and not a carrier) means all the pups will be carriers but they cannot be affected as they only have one copy of the gene. If the sire was instead a carrier or affected, then there is no certainty. Putting it simply -carrier x carrier or affected x carrier is pot luck, much like you can end up with a litter of all dogs or all bitches even though the likelihood is that you'd get both.

Mark R:  DM in Labradors:  I am not agruing with the percentages/figures etc, I was merely commenting that not everyone is a Mathematician who can make head or tail of everything advised when it's all about numbers.  A simple "there is an issue or there isn't an issue" when an owner has just lost their beloved dog would have sufficed and advice to have their living progeny tested if they wanted to take it further,  I don't believe the OP was interested in Breeding further.  Apologies if I mis read the post or mislead anyone.  The question was whether DM was a genetic condition in Labradors or not and the owner was consumed by watching for signs in her lost dog's boy.

Goldmali: DM in Labradors: Exactly "pot luck" it's just like gambling - there is no certainty only odds.

The op may or may not  need the depth of answers but as this forum is open to everyone others will.read the information given and gain more insight into the mode of transmission and the associated risk  .
Also.as.there is testing  available now it will.help.others to test  before breeding  .the eventual.hope in all.breeds would.be that the condition is bred out of course
I for one find these sort of answers fascinating and being able to.learn is  is great

Mark R:  DM in Labradors: > half carrier > half affected  Just read back my first response to the OP.  Assuming half is 50%, that is exactly what I confirmed as being affected ie 50% of puppies born would be affected.  (or maybe none at all which others have highlighted under the banner of 'mother nature') I said nothing about carriers or any other percentages. Please feel free to explain what it is I am not understanding?  Totally confused now.

furriefriends: If this is a Forum is based on giving health testing advice to every situation that's something I have just learned.  Mode of transmission & associated risk is of the upmost importance and I am in no position to disagree with that nor would I ever wish to.  Yes there is testing available now but unless I am wrong again the majority of questions raised by people posting here is regarding "what they can do in their current situation"? not "what tests should I have carried out previously"?  DM in Labrador Retrievers:  Percentages given are that an Affected Dam & a Clear Sire or vice versa could produce a litter of 50% Affected.

DM is a somewhat unusual condition.

Dogs with 2 copies of the mutation are the most at risk of developing the condition, but it does not mean the condition will actual develop. Research is still ongoing to try to find the trigger that affects the mutation & produce the condition.

What is important is that dogs with copies of the mutation must be removed from the gene pool as the best they can produce are carriers & in order to control the spread of the mutation. Depending on the size of the gene pool removal of carriers should also be considered

Assuming half is 50%, that is exactly what I confirmed as being affected ie 50% of puppies born would be affected.

Hoggie you said "If the sire was free of this genetic condition" - if the sire was indeed "free" of it, i.e. clear, then no, you CANNOT get affected offspring. If the sire carried it, then he wasn't "free" of the gene, so a totally different scenario.

Going back to the original question, Lynds30 -how was your dog diagnosed? Was it confirmed by DNA or was it just what the vet thought was the cause? I'm asking because I had a really special dog who started showing signs similar to DM when she was around 12, and as she had been bred from I had her DNA tested straight away. She came back clear. She lived until 14 and when I lost her it was to very similar symptoms to DM, but obviously we then knew that it wasn't DM. One of her daughters lived until almost 18, and the last of her pups still alive is currently 15 ½, with the majory living into their teens.

Golmali:  DM in Labradors: As always I am reading advice from KC site.  When Inherited Genetic Diseases are present then looking at the interperatation tables of 'what this means'  they portray 50% of off spring will be affected.  Sorry Goldmali but if I'm reading things right,  if one parent is free and one parent is affected then there is a ratio that 50% will have the genetic problem - affected or carrier - surely?  or are the KC tables misleading? Who knows ..... the Dam in this instance of the OP was affected.

Goldmali:  DM answer to Lynds 30:  And there we have it at last:  Positivity re longevity! No number crunchig - no this is what should have happened years ago - just a bit of normality! Thank goodness for empathy - hope this gives you a certain amount of comfort Lynds30

Genetics is one of those things that looks super complicated but it isn’t really, it’s just badly taught (in general) and not especially intuitive.

I don’t know very much about DM specifically but for many of the genetic conditions we test for in dogs, you’re looking at a recessive gene where you need two copies of the faulty version to be Affected. One copy is a Carrier.

If you have a dog that’s Clear (two normal copies), they can never produce Affected puppies no matter what the other parent is, because the only thing they can pass on is a normal copy. Some or all of the pups could be Carriers though, depending on the other parent.

For a simple recessive condition:
Clear x clear = 100% clear
Clear x carrier = 50% clear, 50% carrier
Clear x affected = 100% carrier
Carrier x carrier = 25% clear, 50% carrier, 25% affected
Carrier x affected = 50% carrier, 50% affected
Affected x affected = 100% affected

I find the numbers fascinating personally, I always enjoyed figuring out what was going on when you expect a certain ratio but get a significantly different one, but then I am a self-confessed genetics geek!

Probability is strange, as after 25 litters I still have bred a far larger proportion (fortunately) of bitches to dogs.

As I wrote before DM is an unusual condition in that dogs with 2 copies of the mutation do not always develop the condition.

There are tests that can be done to discover a dog's DM status & this link is to the research still being done

> As I wrote before DM is an unusual condition in that dogs with 2 copies of the mutation do not always develop the condition.

Seems not that unusual, as the Glaucoma in our breed is the same.

It is why we could never figure out the mode of inheritance until we got the DNA test.