testing for PSSM 2

[Hormonal Filly]

Dr David Marlin has posted regarding P1 and P2 testing. Didn’t realise Paul is the founder of Equiseq.

 

[shortstuff99]

This article has been posted by Horse and Hound today, did not go down well on the groups!

Owners warned against unvalidated PSSM2 tests after ‘seemingly normal’ horses put down - Horse & Hound

Expert vets are “strongly advising” horse owners against using independent and unvalidated genetic tests for certain conditions – stating that “seemingly normal animals” have been put down as a result of their use. The British Equine Veterinary Association (BEVA) cited tests for myopathies...

www.horseandhound.co.uk

 

[paddy555]

This article has been posted by Horse and Hound today, did not go down well on the groups!

Owners warned against unvalidated PSSM2 tests after ‘seemingly normal’ horses put down - Horse & Hound

Expert vets are “strongly advising” horse owners against using independent and unvalidated genetic tests for certain conditions – stating that “seemingly normal animals” have been put down as a result of their use. The British Equine Veterinary Association (BEVA) cited tests for myopathies...

www.horseandhound.co.uk

haven't had time to read yet but I bet it didn't go down well!!

thanks for posting.

 

[Winger23man]

the text below came up on one of the PSSM FB groups so posting it in case it interests anyone. (I expect most will have seen it already)

(note for anyone new to this it does not relate to the PSSM 1 test which is not problematical)


From the text
I am sharing this in the interest of dispelling some dangerous misinformation that is floating around the equine community at the moment. Please feel free to share as well. It is critical for people to be able to understand what the facts are around this in order to make informed decisions.
As an advocate for the horse, I am always looking for ways that I can support the community towards bettering the lives of these magnificent animals. As an equine professional, it is my duty to keep up with the ever evolving science surrounding the animals we are so lucky to be guardians of.
When I was suggested to look into hair testing for PSSM2 a year ago, I jumped at the opportunity to learn about another way to ensure our horses health and well being. The more I researched, the more data I read, the more I immersed myself in the groups to learn about how people were using these tests - the more concerned I became.
As lovely as it sounds to have a simple test to tell us if our horse has this disease, the science simply doesn’t support that the genetics correlate to the disease or cause the disease - in the same way that a bay horse that has gone blind will test E_A_ if you test for his extension and agouti status, that doesn’t mean that those genes correlate to the blindness. That horse may have a genetic issue that has caused the blindness, and it may even be related to another color gene but that doesn’t mean the genes you tested for when you tested the agouti status caused the disorder in any way. Correlation does not equal causation.
This is one of the hardest things for people to understand, and perhaps why this test has gained such an unusual following despite being dismissed by every major equine medical institution (including ones who are well known for endorsing and utilizing controversial and experimental genetic tests). Your horse may have PSSM2 and a muscle biopsy may have confirmed it, but the genes being present doesn’t mean that they are what caused the disease. The data shows clearly that there isn’t enough correlation between the presence/absence of genes and the presence/absence of the disease to show any relation whatsoever.
Did you know the test failed to identify 57% of symptomatic horses confirmed to have PSSM2 through muscle biopsy? This means that a horse who tested positive through the gold standard for identifying the disease, didn’t have any of the genetic variants this test uses to “identify” the disease according to this test. That statistic alone should be enough to discredit the test as an unreliable way to identify the disease - especially when looking to utilize the test for prepurchase examination or when considering a horse for breeding purposes. Actually, it is enough to discredit the test among experts in the field who can actually understand the science, as every single veterinary professional and genetic specialist I have spoken to on the subject, in various institutions across the United States, has dismissed the test as unreliable and frankly dangerous in it’s misleading nature.
My primary problem with this test is the idea that it should be a part of a pre purchase exam or a breeding assessment - when it is completely unreliable in both being unable to identify horses confirmed to have PSSM2 as well as “identifying” horses who are completely healthy and will never exhibit and single symptom as being “positive”. Basing the purchase of a horse on the negative result of a test which has shown to falsely clear 57% of positive horses is just wildly unfair to everyone involved. To the buyer who expects to never deal with the disease, as well as (and more importantly) to the horse who has been “cleared” and thus won’t be properly tested further down the road if they show symptoms. Equally horrifying is the idea of basing the inclusion or exclusion of a horse in a breeding program based on the results of this test. In breeds in which PSSM2 is present (which is actually documented to only be a limited number of breeds), horse who actually do have PSSM2 could be incorrectly identified as a negative carrier and thus included in the breeding program despite experiencing symptoms, meanwhile horses who do not have PSSM2 and will never experience a single symptom could be culled from the gene pool for having one of these genes. Everyone promoting this test claims they are just looking out for horse welfare - what about the welfare of these horses? What about the owners? The breeders?How is it ethical in any way to be promoting a test that is so unreliable?
If this was a human test it would never be allowed to make it to the public, as it would cause dangerous misinformation and potential for misdiagnosis - however the equine world is vastly under regulated and so this is allowed to be promoted. Even with vets around the world dismissing it as scientifically unsound, it being proven over and over again to be scientifically unsound, people who are unable to understand the science of it are falling into the trap of self-serving biases. It baffles me that despite the fact that there is not a single peer reviewed study which supports this test, meanwhile there are several which completely debunk it - people still are pushing hard for this test. I thought that anyone who did independent research from a neutral perspective (as I did, even testing some of my horses - who came back negative by the way, for anyone who wants to say I am trying to discredit the test due to having “positive” horses) would be able to see the fallacies with this, but unfortunately in the age of anti-science and dangerous misinformation, people are being easily mislead. I am sharing my thoughts on this after a year of deep dives and reaching out to many many experts, and am including links to various sources for those of you who wish to learn more.
To anyone who is being told this is a necessary part of the pre-purchase examination, save your money. If you are concerned, speak with your vet. To anyone with a breeding program being told this is a necessary test to determine whether a horse is fit to breed or not, please consider the potential danger this misinformation could pose to your program if the test is wrong in either direction. This test has not stood up to the rigorous scrutiny needed to ensure accuracy and reliability. Do your research, speak with experts, if you have a horse who concerns you, take the necessary steps to identify and diagnose or clear that horse through scientifically founded methods.
Pictured: slides from a recent talk given by Dr Rebecca Bellone, the leading geneticist at UC DAVIS with 30 years experience in diagnostic markers across species.

I’d like to respond to the lengthy text you inserted

Pssm2 or mim has been around for years back to prehistoric times. It’s not new
No one has suggested not to breed from a positive horse it’s called responsible breeding so lines don’t die out. My goodness people still breed son on mother today and there are no questions asked! We still have connemaras being breed to affected hoofwall ponies resulting in affected ponies
The dna test provides a result for the lifetime of the horse. The gold standard muscle biopsy doesn’t. Did you know a muscle biopsy taken when the horse is not in a dieased state will not show mim Valberg herself admits this but also advises to do a further biopsy in a few years time A muscle biopsy can be negative as the sample is too small, damaged or not in the dieased state
Valberg has refused to work with equisec why? Why would you not work with equisec examining the same pool of horses in the same environment even if it’s just to blow equisecs work out of the water. It makes no sense that you examine different animals. Smacks of elitism

Not all horses with dna positive results end up symptomatic the reason is unknown. Why because more research is needed
Pssm1 is simple its glycogen issues. Mom is more complex in that it’s muscle related
Valberg has decided on her short study warmbloods have a genetic disposition for MIM but not found it in other breeds. As we know the warmblood is made up of different breeds and there are 18 different types of warmbloods the research papers by Valberg do not state which warmbloods

Come on. We have without doubt evidence (if you don’t accept dna) by biopsy of mim. Why has research stopped by vets? Why because Valberg has retired made her money and done a runner or is it because it’s too complex and funding and incentives are not there

People need to keep an open mind. DNA is now extremely advanced. Breeding of affected animals should only take place responsibly I laugh because that won’t happen it currently doesn’t

 

[shortstuff99]

No one as of yet (including equisec) has managed to show a link between the presence of the genetic markers and the expression of disease. That is what is holding it back.

HYPP. PSSM 1 and HWSD etc all have been able to be linked which is why those are "believed".

 

[Exasperated]

I’d like to respond to the lengthy text you inserted

Pssm2 or mim has been around for years back to prehistoric times. It’s not new
No one has suggested not to breed from a positive horse it’s called responsible breeding so lines don’t die out. My goodness people still breed son on mother today and there are no questions asked! We still have connemaras being breed to affected hoofwall ponies resulting in affected ponies
The dna test provides a result for the lifetime of the horse. The gold standard muscle biopsy doesn’t. Did you know a muscle biopsy taken when the horse is not in a dieased state will not show mim Valberg herself admits this but also advises to do a further biopsy in a few years time A muscle biopsy can be negative as the sample is too small, damaged or not in the dieased state
Valberg has refused to work with equisec why? Why would you not work with equisec examining the same pool of horses in the same environment even if it’s just to blow equisecs work out of the water. It makes no sense that you examine different animals. Smacks of elitism

Not all horses with dna positive results end up symptomatic the reason is unknown. Why because more research is needed
Pssm1 is simple its glycogen issues. Mom is more complex in that it’s muscle related
Valberg has decided on her short study warmbloods have a genetic disposition for MIM but not found it in other breeds. As we know the warmblood is made up of different breeds and there are 18 different types of warmbloods the research papers by Valberg do not state which warmbloods

Come on. We have without doubt evidence (if you don’t accept dna) by biopsy of mim. Why has research stopped by vets? Why because Valberg has retired made her money and done a runner or is it because it’s too complex and funding and incentives are not there

People need to keep an open mind. DNA is now extremely advanced. Breeding of affected animals should only take place responsibly I laugh because that won’t happen it currently doesn’t

Well you’re 100% right about irresponsible breeding, whether for quick profit, exotic colour, cartoon-head Arabs or some other nonsense.
Also about the ‘snapshot unreliability’ of biopsy - which is neither pleasant nor cheap to do.
It is beyond obvious that more detailed research into PSSM 2 / MIM is required. Which will probably identify, separate, ‘new’ pathologies, but also that possible genetic links must be fully part of that research. Genetic science advances all the time, scientists are not ostriches.
I understood that Liverpool Uni. Vet School ARE currently researching familial links in muscle myopathies?
Their Senior Equine Vet Nurse posted to that effect on here, re the project she’s involved with - Laura? Lara? Lauren?
And all power to their elbow, because greater understanding is sorely needed.

 

[Exasperated]

Well you’re 100% right about irresponsible breeding, whether for quick profit, exotic colour, cartoon-head Arabs or some other nonsense.
Also about the ‘snapshot unreliability’ of biopsy - which is neither pleasant nor cheap to do.
It is beyond obvious that more detailed research into PSSM 2 / MIM is required. Which will probably identify, separate, ‘new’ pathologies, but also that possible genetic links must be fully part of that research. Genetic science advances all the time, scientists are not ostriches.
I understood that Liverpool Uni. Vet School ARE currently researching familial links in muscle myopathies?
Their Senior Equine Vet Nurse posted to that effect on here, re the project she’s involved with - Laura? Lara? Lauren?
And all power to their elbow, because greater understanding is sorely needed.

my mistake: leah3horses, 29/09/23, and testing the PSSM2 variants at Liverpool, although genetic variants

Well you’re 100% right about irresponsible breeding, whether for quick profit, exotic colour, cartoon-head Arabs or some other nonsense.
Also about the ‘snapshot unreliability’ of biopsy - which is neither pleasant nor cheap to do.
It is beyond obvious that more detailed research into PSSM 2 / MIM is required. Which will probably identify, separate, ‘new’ pathologies, but also that possible genetic links must be fully part of that research. Genetic science advances all the time, scientists are not ostriches.
I understood that Liverpool Uni. Vet School ARE currently researching familial links in muscle myopathies?
Their Senior Equine Vet Nurse posted to that effect on here, re the project she’s involved with - Laura? Lara? Lauren?
And all power to their elbow, because greater understanding is sorely needed.

Well you’re 100% right about irresponsible breeding, whether for quick profit, exotic colour, cartoon-head Arabs or some other nonsense.
Also about the ‘snapshot unreliability’ of biopsy - which is neither pleasant nor cheap to do.
It is beyond obvious that more detailed research into PSSM 2 / MIM is required. Which will probably identify, separate, ‘new’ pathologies, but also that possible genetic links must be fully part of that research. Genetic science advances all the time, scientists are not ostriches.
I understood that Liverpool Uni. Vet School ARE currently researching familial links in muscle myopathies?
Their Senior Equine Vet Nurse posted to that effect on here, re the project she’s involved with - Laura? Lara? Lauren?
And all power to their elbow, because greater understanding is sorely needed.

My mistake:
Leah3horses, 29/09/23, and researching the PSSM 2 VARIANTS at Liverpool, which variants are what the genetic hair testing purports to show, no?

 

[Winger23man]

Dr David Marlin has posted regarding P1 and P2 testing. Didn’t realise Paul is the founder of Equiseq.

Dr marlin doesn’t want to accept anything unless it involves a sale to his company

 

[Winger23man]

my mistake: leah3horses, 29/09/23, and testing the PSSM2 variants at Liverpool, although genetic variants


My mistake:
Leah3horses, 29/09/23, and researching the PSSM 2 VARIANTS at Liverpool, which variants are what the genetic hair testing purports to show, no?

I’d like to know more and if they are working with equisec. I suspect not

 

[Tiddlypom]

The reason that I swerved the muscle biopsy on my symptomatic PSSM1 -ve mare was because of the known issue with false -ves. By then I’d got a management system which worked well and continues to do so 7 years on. Vet would have preferred me to get the biopsy done for completeness, but respects my reasons not to have an invasive test done on her. Vet expected the biopsy to be +ve.

I certainly wouldn’t bother with the hyped up non validated PSSM2 genetic tests as they stand currently.

 

[FieldOrnaments]

how are muscle biopsies performed - i understand it's take a sample of muscle tissue, and examine under a microscope, but how do they actually do it? do they only examine 1 sample or multiple?

 

[Exasperated]

how are muscle biopsies performed - i understand it's take a sample of muscle tissue, and examine under a microscope, but how do they actually do it? do they only examine 1 sample or multiple?

Usually involves sedating the horse, standing it in stocks or under restraint (generally at the vet practice rather than your own stable) and punching a sizeable hole into its inner thigh. Not pretty.
Next time you want to fasten fillet strings, groom behind etc, horse isn't overly keen....
both false positives and false negatives have also been associated with this procedure, and for the record, my equine vet was extremely loath to perform.
If you've found / stumbled upon a management regime that WORKS - that's the Holy Grail for your horse anyway, so well done tiddlypop!
Universities often work with commercial investors into research, not always healthy, but Liverpool have an excellent reputation - perhaps someone might like to ask them, via poster Leah?

 

[khalswitz]

how are muscle biopsies performed - i understand it's take a sample of muscle tissue, and examine under a microscope, but how do they actually do it? do they only examine 1 sample or multiple?

I’m a geneticist with a PhD in genetics of neuromuscular disease in horses - and used to be based at a lab that did this work.

You only need one sample, although some vets will submit multiple from different muscles if they feel the need. Thin slices are taken from that sample and stained to identify different things - you can look at glycogen, or inflammatory cells, or lipid deposits, or use specific stains to look at eg the function muscle metabolism enzymes, or use more general ones for major cell architecture. You can end up with a panel of different stains looking at different aspects and functions of the muscle. The histological picture of a muscle sample is variable depending on how active the disease process is in the muscle and which muscle the vet has biopsied - but equally we can see evidence of damage and repair cycles from episodes of tying up months beforehand, so there’s more to see than many people in these FB groups claim.

On another note - I really wish people would stop using ‘muscle integrity myopathy’/‘MIM’. This term was invented after the studies came out showing no association between these tests and PSSM2 - there is not a single instance of this phrase being used in any of the literature, it’s literally never been described even in a case report in the EVJ. I have only ever found it on Equiseq/Generatio webpages and on Facebook.

 

[FieldOrnaments]

Ahh I meant what is done to the horse really -- thanks both though

 

[Tiddlypom]

On another note - I really wish people would stop using ‘muscle integrity myopathy’/‘MIM’. This term was invented after the studies came out showing no association between these tests and PSSM2 - there is not a single instance of this phrase being used in any of the literature, it’s literally never been described even in a case report in the EVJ. I have only ever found it on Equiseq/Generatio webpages and on Facebook

Thank you so much for posting this.

I’d never heard of MIM until very recently. It’s another cooked up term from the usual suspects connected to the non validated tests, then.

 

[FieldOrnaments]

I think it's basically a sciency-sounding term concocted to make people think they're giving their money to something legitimate

 

[khalswitz]

I think it's basically a sciency-sounding term concocted to make people think they're giving their money to something legitimate

Don’t get me wrong - there’s debate in the scientific and veterinary communities about whether there are different diseases within the syndrome of ERS/RER/PSSM2/general exertional myopathy syndrome. So proposing new potential names isn’t a bad thing. But using a new name never proposed in the literature or alongside a characterised myopathy phenotype to sell tests is not in my opinion good practice.

People complain about vets not knowing about the diseases - no wonder!

 

[SEL]

The nutritionist who has been working on the pssm 2 / MIM horses in her home country (Germany?) was on FB the other day saying she reckoned the majority of owners who contact her thinking they have a pssm/ MIM issue go on to find it's actually something else.

She also gets owners to blood test manganese levels - got me wondering if there's something like vitamin E deficiency but with manganese which presents like a myopathy

 

[Winger23man]

The reason that I swerved the muscle biopsy on my symptomatic PSSM1 -ve mare was because of the known issue with false -ves. By then I’d got a management system which worked well and continues to do so 7 years on. Vet would have preferred me to get the biopsy done for completeness, but respects my reasons not to have an invasive test done on her. Vet expected the biopsy to be +ve.

I certainly wouldn’t bother with the hyped up non validated PSSM2 genetic tests as they stand currently.

We all have our views. If you haven’t owned a mim affected horse and spent a fortune on tests and vets to drawn a complete blank you haven’t a clue and very blinkered In a few years you will think differently

 

[Tiddlypom]

We all have our views. If you haven’t owned a mim affected horse and spent a fortune on tests and vets to drawn a complete blank you haven’t a clue and very blinkered In a few years you will think differently

I appreciate that I was fortunate to be able to find a way to manage my horse’s symptoms. Prior to that I had been at the point of returning her to her breeder as she was so miserable with me.

Far from being blinkered I am open minded and try to think outside the box. That is what led me to get my horse tested for PSSM1 seven years ago, even though at the time my vet hadn’t suggested it. I dislike commercial companies (or indeed anyone else) who prey on vulnerable people scrabbling for answers.

 

[catembi]

The nutritionist who has been working on the pssm 2 / MIM horses in her home country (Germany?) was on FB the other day saying she reckoned the majority of owners who contact her thinking they have a pssm/ MIM issue go on to find it's actually something else.

She also gets owners to blood test manganese levels - got me wondering if there's something like vitamin E deficiency but with manganese which presents like a myopathy

Yes, I saw that as well & thought it was very interesting. Mine tested n/px. Marion said to me that she wouldn't hesitate to buy an n/px horse & that it's fine. I was surprised at the time, but now less surprised as we also have grade 2 ulcers which haven't responded to treatment and we are now doing extensive xrays this week as the vet strongly suspects either ks which is leading to an odd stance or something wrong with the hocks which is leading to a very stiff back. So n/px may not be the 'main event' or even a factor.

The trouble is, the symptoms of PSSM, ulcers & ks are all very similar. Girthy, not wanting to work, etc etc. It's very easy to think you've found the cause, when in fact the 'cause' is really a symptom of something else. My old ex racer had non resolving ulcers, so we xrayed his back which led to ks surgery, but that didn't really help & we found that he is also p3/px. Once the ks was sorted, the ulcers resolved, but the lack of forward motion remained. It could have been any one of those things on its own...or something completely different that we didn't find.

It's all trial & error, & sometimes it feels like mostly error...

 

[SEL]

Yes, I saw that as well & thought it was very interesting. Mine tested n/px. Marion said to me that she wouldn't hesitate to buy an n/px horse & that it's fine. I was surprised at the time, but now less surprised as we also have grade 2 ulcers which haven't responded to treatment and we are now doing extensive xrays this week as the vet strongly suspects either ks which is leading to an odd stance or something wrong with the hocks which is leading to a very stiff back. So n/px may not be the 'main event' or even a factor.

The trouble is, the symptoms of PSSM, ulcers & ks are all very similar. Girthy, not wanting to work, etc etc. It's very easy to think you've found the cause, when in fact the 'cause' is really a symptom of something else. My old ex racer had non resolving ulcers, so we xrayed his back which led to ks surgery, but that didn't really help & we found that he is also p3/px. Once the ks was sorted, the ulcers resolved, but the lack of forward motion remained. It could have been any one of those things on its own...or something completely different that we didn't find.

It's all trial & error, & sometimes it feels like mostly error...

At one point with the Appy's investigations I felt like I was on every single FB page and her symptoms fit virtually everything.

Ulcer page - yup, definitely ulcers
Stifle problems - absolutely (she didn't despite Tom Beech being adamant there would be a problem)
PSD - explained everything
PSSM- well she's positive so what do you expect, change her diet, rug her, try and different brand of x,y,z

I have actually got a packet of Forage Plus manganese sitting in my feed room wondering whether to do a mini trial of one permanently broken Appaloosa to see if it does make a difference. She's got a horribly bruised back foot at the moment though so no point until that has healed up. No idea how she did it but I was blaming her unwillingness to walk out on the PSSM until I cleaned off her hoof and spotted what looks like a small hole and a big bruise. It is so, so easy to blame a known issue than to go looking for anything else - I have the same problem when I go to my GP!!

 

[Winger23man]

I appreciate that I was fortunate to be able to find a way to manage my horse’s symptoms. Prior to that I had been at the point of returning her to her breeder as she was so miserable with me.

Far from being blinkered I am open minded and try to think outside the box. That is what led me to get my horse tested for PSSM1 seven years ago, even though at the time my vet hadn’t suggested it. I dislike commercial companies (or indeed anyone else) who prey on vulnerable people scrabbling for answers.

You are believing the misinformation spread by Valberg and her team on mom. You do know that she profited from selling products for affected horses. Encouraging owners to do a muscle biopsy of unaffected animals then getting a negative then saying re test in a few years time

The fact remains Valberg has refused to work with “ commercial companies “. You have to ask why even if it’s to completely blow their theory out of the water. Instead and tested a different set of healthy horses and bingo and didn’t find the answers!

 

[khalswitz]

You are believing the misinformation spread by Valberg and her team on mom. You do know that she profited from selling products for affected horses. Encouraging owners to do a muscle biopsy of unaffected animals then getting a negative then saying re test in a few years time

The fact remains Valberg has refused to work with “ commercial companies “. You have to ask why even if it’s to completely blow their theory out of the water. Instead and tested a different set of healthy horses and bingo and didn’t find the answers!

I don’t blame Valberg for refusing to work with EquiSeq - they were using her name and recommendations whilst refusing to share their evidence for what they claimed was a distinct genotype/phenotype.

Yes she has profited from the PSSM1 genetic test patent and from selling feeds - but the evidence for these was all published and peer reviewed so that people could make informed decisions about using them. EquiSeq have made a fortune and never given any evidence for their claims at all - when I asked them in 2017 they were adamant they were due to publish imminently and yet it’s never happened. It makes it look like they don’t have good evidence for what they’re selling.

And part of a scientifically robust validation would always include testing a different, independent set of affected and healthy horses - it’s only if the results can be repeated that we get good evidence it’s a true result. This is good science in action and what we would want to see.

Muscle biopsies are still the gold standard for most muscle diseases in horses, that’s why vets and scientists recommend them. (Edit - there are validated tests for PSSM1, malignant hyperthermia (MH), hyperkalaemic periodic paralysis (HYPP), glycogen branching enzyme deficiency (GBED), congenital myotonia (CM), and myosin heavy chain myopathy (MYHM) which can result in immune mediated myositis (IMM), and if your vet’s differentials include them then those would be the typical choice over a muscle biopsy. But for the range of other myopathies (mitochondrial myopathy, vacuolar myopathy, idiopathic exertional myopathies, fibrotic myopathy, PSSM2 and RER etc) you’re only going to get an idea what is going on from histology of a muscle biopsy sample.)

 

[Winger23man]

I don’t blame Valberg for refusing to work with EquiSeq - they were using her name and recommendations whilst refusing to share their evidence for what they claimed was a distinct genotype/phenotype.

Yes she has profited from the PSSM1 genetic test patent and from selling feeds - but the evidence for these was all published and peer reviewed so that people could make informed decisions about using them. EquiSeq have made a fortune and never given any evidence for their claims at all - when I asked them in 2017 they were adamant they were due to publish imminently and yet it’s never happened. It makes it look like they don’t have good evidence for what they’re selling.

And part of a scientifically robust validation would always include testing a different, independent set of affected and healthy horses - it’s only if the results can be repeated that we get good evidence it’s a true result. This is good science in action and what we would want to see.

Muscle biopsies are still the gold standard for most muscle diseases in horses, that’s why vets and scientists recommend them. (Edit - there are validated tests for PSSM1, malignant hyperthermia (MH), hyperkalaemic periodic paralysis (HYPP), glycogen branching enzyme deficiency (GBED), congenital myotonia (CM), and myosin heavy chain myopathy (MYHM) which can result in immune mediated myositis (IMM), and if your vet’s differentials include them then those would be the typical choice over a muscle biopsy. But for the range of other myopathies (mitochondrial myopathy, vacuolar myopathy, idiopathic exertional myopathies, fibrotic myopathy, PSSM2 and RER etc) you’re only going to get an idea what is going on from histology of a muscle biopsy sample.)

It’s Valberg who refused not the other way round and there is evidence to prove that too. Can you prove your statement perhaps Valberg would comment herself

Yes a muscle biopsy is the gold standard in medicine however it isn’t fool proof as Valberg herself admits

You will not find the disease by muscle biopsy in a healthy young horse

DNA has advanced over the years

 

[shortstuff99]

Yes DNA has advanced but all it will tell you is if a gene region is present or not, what it won't tell you is if that gene causes disease. For that you will need to do such things a gene knock down experiment or a study of 1000s of individuals and then mapping it to disease.

Just saying a gene is present does not imply it is causing that disease.

 

[Winger23man]

Yes DNA has advanced but all it will tell you is if a gene region is present or not, what it won't tell you is if that gene causes disease. For that you will need to do such things a gene knock down experiment or a study of 1000s of individuals and then mapping it to disease.

Just saying a gene is present does not imply it is causing that disease.

Yes you have just answered your own argument. The “ commercial companies “ advise you the gene s present. Most people test as they have exhausted vet and everything else because their horse symptomatic liked not the muscle biopsy is often wrong as the muscle needs to be in the dieased state to pick up the issues. Not all dna possitive horses become symptomatic not enough research has been done and the two sides need to work together which they are not doing

 

[I'm Dun]

Yes you have just answered your own argument. The “ commercial companies “ advise you the gene s present. Most people test as they have exhausted vet and everything else because their horse symptomatic liked not the muscle biopsy is often wrong as the muscle needs to be in the dieased state to pick up the issues. Not all dna possitive horses become symptomatic not enough research has been done and the two sides need to work together which they are not doing

I was pro the type 2 test, until it turned out there was no research to be published by the company, and there is literally nothing linking these genes to any sort of disease.

 

[SEL]

Yes you have just answered your own argument. The “ commercial companies “ advise you the gene s present. Most people test as they have exhausted vet and everything else because their horse symptomatic liked not the muscle biopsy is often wrong as the muscle needs to be in the dieased state to pick up the issues. Not all dna possitive horses become symptomatic not enough research has been done and the two sides need to work together which they are not doing

Equiseq has made a fortune with the commercial selling of these tests and were at fund raising roadshows raising investor capital.

Irrespective of whether Valberg is interested they should have the funding to do the research. It was 2-3 years ago that Paul said they'd produce a paper on the k1 variant. It is pretty catastrophic in humans and would show on biopsy - so if it affects horses then it should show on biopsy.

 

[shortstuff99]

Yes you have just answered your own argument. The “ commercial companies “ advise you the gene s present. Most people test as they have exhausted vet and everything else because their horse symptomatic liked not the muscle biopsy is often wrong as the muscle needs to be in the dieased state to pick up the issues. Not all dna possitive horses become symptomatic not enough research has been done and the two sides need to work together which they are not doing

Yes but that on its own is useless, you are relying on the premise that these genes = disease when they may not. thats like me telling you your horse has 18S gene region or COX1 or something, doesn't really tell you much.

If you knew that specific region caused x then very useful, but it doesn't, so you are still just taking a shot in the dark.