Early research shows a genetic component to KS

[DirectorFury]

I think this is something that a lot of people have suspected for a while, but it’s amazing that they’ve narrowed down the changes in two chromosomes and their impact.

https://thehorse.com/196838/researc...BxtOerlkrykX4MnH6qdNDp8j1FNo7gvVgmWV2DVv6RcG8

 

[TheMule]

It¡s a really interesting bit of research. I wonder if vetting horses in the future will include genetic testing as standard such our knowledge of the heritability of different conditions is improving all the time

 

[Littlewills]

Now there is money to be made with people paying for genetic testing, it seems to be having a really positive affect on the research being done. The more we know about these things the quicker we can start to breed them out. New forest ponies are pretty much clear of PSSM1 in a generation as mandatory testing was brought in. Thats amazing progress and soemthing every breed society should be doing.

The downside is both the warmblood and TB breeding industry is going to be heavily affected, and I'm just not sure if enough people will make enough of a fuss for enough to be done.

 

[Pearlsacarolsinger]

That is interesting let's hope it stops people turning away their KS mares to have a foal.

 

[Littlewills]

It¡s a really interesting bit of research. I wonder if vetting horses in the future will include genetic testing as standard such our knowledge of the heritability of different conditions is improving all the time

When I buy another I'll do both tests for PSSM before purchase and I've never vetted a horse in my life before. The type 2 test isnt peer reviewed yet, but the results are conclusive enough for me to give any positive horse a hard swerve. And to walk away if the sellers wont permit testing.

 

[ycbm]

I've always thought it and previously been told I'm wrong. I know people breeding from KS mares whose vets told them it was OK.
.

 

[Gloi]

Interesting study and not unexpected that it has a genetic component. Wonder if they are also tracking down the genetic markers for c6/c7 malformation.

 

[Trouper]

Any research is welcome on this. However if progress on breeding it out is as slow and uncertain as that for hip dysplasia in GSD's, it's going to be a long old road.

 

[shamrock2021]

It probably improve horse breeding and stop people breeding mares that have it. I say it will be used in vetting in the future.

 

[Gloi]

It's going to be down to money on I'm sure whether the breeders will take these things seriously enough to test and only breed from non carriers.

 

[DirectorFury]

Wonder if they are also tracking down the genetic markers for c6/c7 malformation.

Apparently yes, though I've heard that the big TB breeders are trying to block this. I'm v interested in this as I want to put my mare to a TB/TBx but can't justify taking the risk until there's more knowledge about the mechanism of the c6/c7 mutation, and equally don't feel able to ask the stud if they have c6/c7 xrays of the stallion I'm interested in using!

I hope that these discoveries lead to more responsible breeding, but I suspect it won't. How many of the major studs in Europe just churn out foal after foal after foal in the hope of one or two of them doing well? If half of their foundation mares suffer from KS it might be too widespread to eradicate. It might be more possible if horse prices keep going up, but not if they stay at the level where breeders are effectively subsidising the rest of the industry.

 

[Errin Paddywack]

Responsible breeders who really care about their stock will take note of this but many won't unfortunately. I noticed on one of the PSSM facebook sites, someone who has a mare PSSM P1/P1. That mare has a son and daughter both P1/P1. I could be doing them an injustice, they may not have found out about their mare's status until after the foals arrived. I sincerely hope they don't breed more foals from her or her daughter.

 

[Gloi]

Apparently yes, though I've heard that the big TB breeders are trying to block this. I'm v interested in this as I want to put my mare to a TB/TBx but can't justify taking the risk until there's more knowledge about the mechanism of the c6/c7 mutation, and equally don't feel able to ask the stud if they have c6/c7 xrays of the stallion I'm interested in using!

The lines this came from are known, it needs the breeders to be more open and go public with the information but I can't see it happening soon.

 

[sbloom]

I just hope it doesn't detract from the need to educate on correct posture, I wonder if even those with the genetic issues could avoid it actually becoming symptomatic. I know of one mare that exhibits mild KS symptoms, and I believe has had xrays that show there is some crowding, but when worked in hand into better posture, and fittened back into work slowly, is perfectly happy.

 

[FinnishLapphund]

The trouble with gene tests is that, at least for the time being, they only tests for so and so specific gene, and there is no guarantee that a horse free of for example the PSSM1 gene, doesn't have other unknown genetic problems.

As I understand it, PSSM1 is a dominant disease where a horse only needs 1 copy of PSSM1 to have it. So with that disease I can understand if responsible breeders doesn't have much options, other than not using any horse with that gene in breeding.
But in DirectorFury's interesting link, they're talking about 2 specific chromosomes, Chromosome 16, and 25, which appears to have regions that affects the severity of Kissing Spines. A 3rd chromosome, Chromosome 14, also seems to play an important part.
On top of that, it says that the horse's height "has a very, very strong impact".

So, does it mean that they're dominant, or recessive? Does a horse have to have a problem with all 3 mentioned chromosomes, with 2, or is it enough with 1... And where does the height come in, and how does it affect things?

Hypothetically, if all stallion, and mares, with the "faulty" chromosomes is excluded from breeding, how does that affect the overall gene pool? After all, the more narrow the gene pool, the bigger risk for new, unknown problems to occur.

 

[Regandal]

I just hope it doesn't detract from the need to educate on correct posture, I wonder if even those with the genetic issues could avoid it actually becoming symptomatic. I know of one mare that exhibits mild KS symptoms, and I believe has had xrays that show there is some crowding, but when worked in hand into better posture, and fittened back into work slowly, is perfectly happy.

It’s an interesting subject. They have found kissing spines, with impingement, on post mortem and the horse has been asymptomatic .

 

[Melody Grey]

That is interesting let's hope it stops people turning away their KS mares to have a foal.

An instructor/ low level event rider near to me has put her OTTB in foal since retiring it due to KS- stopped listening once I realised this! ?‍

 

[Melody Grey]

It’s a positive that this research is out there and hopefully it’ll gather momentum. I think it’ll take something drastic to have much of an effect though- referring to TBs for racing, a lot have KS that develops as they mature- since so many are produced and so many come out of racing so young, I doubt anything will change unless the re-sale value of ex-racers increases substantially.

 

[LiquidMetal]

The lines this came from are known, it needs the breeders to be more open and go public with the information but I can't see it happening soon.

I’ve read the malformation is from the Messenger and Diomed lines. Sires from the 1700s. The reason the bloodline hasn’t been widely published is because it’s too far back to actually do anything about.

 

[Marigold4]

The trouble with gene tests is that, at least for the time being, they only tests for so and so specific gene, and there is no guarantee that a horse free of for example the PSSM1 gene, doesn't have other unknown genetic problems.

As I understand it, PSSM1 is a dominant disease where a horse only needs 1 copy of PSSM1 to have it. So with that disease I can understand if responsible breeders doesn't have much options, other than not using any horse with that gene in breeding.
But in DirectorFury's interesting link, they're talking about 2 specific chromosomes, Chromosome 16, and 25, which appears to have regions that affects the severity of Kissing Spines. A 3rd chromosome, Chromosome 14, also seems to play an important part.
On top of that, it says that the horse's height "has a very, very strong impact".

So, does it mean that they're dominant, or recessive? Does a horse have to have a problem with all 3 mentioned chromosomes, with 2, or is it enough with 1... And where does the height come in, and how does it affect things?

Hypothetically, if all stallion, and mares, with the "faulty" chromosomes is excluded from breeding, how does that affect the overall gene pool? After all, the more narrow the gene pool, the bigger risk for new, unknown problems to occur.

Very good questions! Thank you. It would make a huge difference to breeding whether it was dominant or recessive

 

[Frumpoon]

I just hope it doesn't detract from the need to educate on correct posture, I wonder if even those with the genetic issues could avoid it actually becoming symptomatic. I know of one mare that exhibits mild KS symptoms, and I believe has had xrays that show there is some crowding, but when worked in hand into better posture, and fittened back into work slowly, is perfectly happy.

Absolutely this!

I really think posture and subtle lameness account for a lot of the KS I have seen

 

[Michen]

What about the idea that KS is supposedly prevalent in a huge proportion of horses, just that most aren't symptomatic?

I had thought it was something like 7/10 horses supposedly have KS if you x rayed every horse on a yard.

 

[Wishfilly]

This is really interesting and thank you for sharing!

Personally, I doubt it will have much impact on bigger TB studs- they aren't breeding with the longevity of the horse's career in mind anyway. But for hobby breeders and those breeding sports horses etc, it will hopefully have an impact!

The idea of "dominant" and "recessive" genes is a bit of an oversimplification, especially when multiple genes are involved. And there's also probably still environmental influences in terms of severity.

I'm not an expert, but my interpretation is that if the "kissing spine" mutation is present in the chromosome 14 region, then the horse is far more likely to develop kissing spines than a horse without this gene. However, I would assume that the horse's life/work etc would impact on the severity of the case. If the horse has the Chromosome 16 mutation, then it is more likely to develop more severe KS and if the Chromosome 25 mutation is present, then it is even more likely to develop very severe KS.

I wonder if those with just the chromosome 14 mutation are those more likely to present as asymptomatic?

The article does also acknowledge the benefits of physical therapy and a low stress career for these horses, as well.

I think whilst research is ongoing, it would be massively irresponsible to breed from a KS mare or stallion, but with time, we might be able to better understand the inheritance and identify "safe" matings for some animals?

 

[whiteflower]

I just hope it doesn't detract from the need to educate on correct posture, I wonder if even those with the genetic issues could avoid it actually becoming symptomatic. I know of one mare that exhibits mild KS symptoms, and I believe has had xrays that show there is some crowding, but when worked in hand into better posture, and fittened back into work slowly, is perfectly happy.

This, I'm sure there is a genetic element but Im suspicious that a large element of some of the symptomatic horses, especially those that develop symptoms later in life may be down to management, posture and how they are ridden. I myself had one that developed mild KS later and I'm convinced that was down to poor posture and poor riding practice. She has been rehabilitated to improve posture and ridden in a more biomechanically positive way and has come back to competing and continued to do so the last 7 years. I think it may be one of those things where there is genetic issues for some but other factors may be at play in it being symptomatic. Very pleasing to see some research going on though

 

[Wishfilly]

This, I'm sure there is a genetic element but Im suspicious that a large element of some of the symptomatic horses, especially those that develop symptoms later in life may be down to management, posture and how they are ridden. I myself had one that developed mild KS later and I'm convinced that was down to poor posture and poor riding practice. She has been rehabilitated to improve posture and ridden in a more biomechanically positive way and has come back to competing and continued to do so the last 7 years. I think it may be one of those things where there is genetic issues for some but other factors may be at play in it being symptomatic. Very pleasing to see some research going on though

The article specifically acknowledges that physical therapy and sympathetic riding can play a role in managing kissing spines.

There are at least three genes involved:

Chromosome 14, which has a high association with KS being present.

And then Chromosome 16 and 25, which are associated with severity.

I would imagine a horse with only the Chromosome 14 mutation is far more likely to be able to be managed via good riding/good posture etc, and not being asked to do work (the article references reining, for example) which may cause additional stresses. I would assume that a horse with all three mutations would be far less easy to manage.

So there are definitely lots of factors in play, and the research acknowledges this. But this also still suggests that breeding from a mare with kissing spines would be a bad idea- in the same way that breeding from a horse with poor conformation but that is sound is not a great idea!

 

[Marigold4]

A large number of brood mares at stud farms are never ridden so KS and its problems may never come to light. I wonder if breeders will now be x-raying for KS before using their mare? I don't think so.

 

[Marigold4]

This is really interesting and thank you for sharing!

Personally, I doubt it will have much impact on bigger TB studs- they aren't breeding with the longevity of the horse's career in mind anyway. But for hobby breeders and those breeding sports horses etc, it will hopefully have an impact!

The idea of "dominant" and "recessive" genes is a bit of an oversimplification, especially when multiple genes are involved. And there's also probably still environmental influences in terms of severity.

I'm not an expert, but my interpretation is that if the "kissing spine" mutation is present in the chromosome 14 region, then the horse is far more likely to develop kissing spines than a horse without this gene. However, I would assume that the horse's life/work etc would impact on the severity of the case. If the horse has the Chromosome 16 mutation, then it is more likely to develop more severe KS and if the Chromosome 25 mutation is present, then it is even more likely to develop very severe KS.

I wonder if those with just the chromosome 14 mutation are those more likely to present as asymptomatic?

The article does also acknowledge the benefits of physical therapy and a low stress career for these horses, as well.

I think whilst research is ongoing, it would be massively irresponsible to breed from a KS mare or stallion, but with time, we might be able to better understand the inheritance and identify "safe" matings for some animals?

Isn't dominant or recessive really important though? So if the KS gene were recessive, and you bred to a horse with no KS gene, you would only get a carrier because you need two copies of the gene to get an affected horse. Whereas with a dominant gene you couldn't breed at all because only one gene is needed for an affected horse? So the difference is really important.

 

[Wishfilly]

Isn't dominant or recessive really important though? So if the KS gene were recessive, and you bred to a horse with no KS gene, you would only get a carrier because you need two copies of the gene to get an affected horse. Whereas with a dominant gene you couldn't breed at all because only one gene is needed for an affected horse? So the difference is really important.

I'm by no means an expert on genetics, but this is a bit of an oversimplification. For starters, it is possible for genes to be co-dominant. So having one copy of the gene could still have an impact, but less so than if you have two copies.

This is like the dilute coat colour- so if you have a horse with one copy of the dilute gene, it is dun or palomino, but if you have two it is perlino or cremello.

The research also mentions associations with height, and less strongly sex. So it might be that you could breed from a healthy "carrier" and produce tall offspring that then goes on to develop kissing spines.

Because we are talking about three separate genes here, it's likely the interaction will have an impact. So if the horse doesn't have the Chromosome 14 mutation, it may not matter which genes are present in Chromosome 16, and Chromosome 25, because their impacts will only be expressed if the horse actually develops kissing spines. As I understand it, 16 and 25 are associated with increased severity only.

Personally, I also believe it's desirable to breed unhealthy alleles out of a population full stop, even if they are truly recessive.

 

[Marigold4]

I'm by no means an expert on genetics, but this is a bit of an oversimplification. For starters, it is possible for genes to be co-dominant. So having one copy of the gene could still have an impact, but less so than if you have two copies.

This is like the dilute coat colour- so if you have a horse with one copy of the dilute gene, it is dun or palomino, but if you have two it is perlino or cremello.

The research also mentions associations with height, and less strongly sex. So it might be that you could breed from a healthy "carrier" and produce tall offspring that then goes on to develop kissing spines.

Because we are talking about three separate genes here, it's likely the interaction will have an impact. So if the horse doesn't have the Chromosome 14 mutation, it may not matter which genes are present in Chromosome 16, and Chromosome 25, because their impacts will only be expressed if the horse actually develops kissing spines. As I understand it, 16 and 25 are associated with increased severity only.

Personally, I also believe it's desirable to breed unhealthy alleles out of a population full stop, even if they are truly recessive.

I definitely agree with you about this and am spending a fortune testing my mare for everything under the sun before breeding, but just going on experience with connies and recessive HWSD. So people are still using stallions that are N/HWSD. As long as their mare is N/N they can't get a HWSD foal. Eventually this disease will be bred out like this even if some carriers are bred along the way. I haven't been involved in this but just interested to hear if you think this is wrong and carriers shouldn't be bred at all. I don't know much about genes but would be interested to know if this is not OK

 

[Wishfilly]

I definitely agree with you about this and am spending a fortune testing my mare for everything under the sun before breeding, but just going on experience with connies and recessive HWSD. So people are still using stallions that are N/HWSD. As long as their mare is N/N they can't get a HWSD foal. Eventually this disease will be bred out like this even if some carriers are bred along the way. I haven't been involved in this but just interested to hear if you think this is wrong and carriers shouldn't be bred at all. I don't know much about genes but would be interested to know if this is not OK

My understanding is that HWSD is caused by a single mutation, and it is completely recessive- i.e. there is no way that a carrier can display symptoms of the disease. In this case, there are less negatives to breeding from a carrier with an N/N mare. It's also relevant that there is an easy and cheap test for HWSD and the Connemara pony society requires carriers to have this recorded in their passport.

Personally, I think there are enough quality connemara ponies out there that are N/N- so there is no need to breed from a carrier. If this was done, you could probably remove the HWSD gene from the population entirely, which would benefit future generations. If we were talking about a much smaller population, I might feel differently!

The genetics of KS seem a lot more complex, and it doesn't seem like we fully understand how the three genes interact, how the genes interact with the environment or if other genes might be involved too. Due to this, I don't think it would be ethical to breed from a horse which showed symptoms of kissing spine, even if the other parent was healthy.

If, with future research, it was found that the mutation on Chromosome 14 was a true recessive gene regardless of environmental factors, (for example) then there might be reasons to breed from a parent with the mutation and produce offspring which are carriers. But the Chromosome 16 and Chromosome 25 genes seem like they could impact animals that had KS with purely environmental causes (and the research so far suggests that there may be some cases which are purely environmental).

I hope that makes sense!