On the same page are listed gelderlander stallions that are positive for WFFS.

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Garbage Eurodressage article title aside, I am pleased that it seems that the Trakehner Verband opened the doors to this when they posted findings earlier this week. Further contextualisation of those findings as Westfalen has done (represented by the article above) is super helpful to help people keep the information in context if they haven’t been following the entire thing.

Thoroughbreds Bay Ronald and Dark Ronald are represented in every carrier of WFFS and likely carriers of the gene. descendants Furioso, Ladykiller, and Der Lowe (among others) are possible entry points for the gene mutation to have entered the warmblood population. (This also explains how it is in thoroughbreds, the closed book Trakehners, etc.) However, the ancestry of the gene itself and where it originated is likely generations earlier, though perhaps that will never be available to us to trace, though Dr Winand identifies Arabians as where it first occurred.

Fascinating to see this informaion revealed and props to everyone who undertook this project.

A university is also looking at the connection of aborted pregnancies to WFFS. (ETA: I am glad that Westfalen also included their preliminary findings re:foal loss and WFFS. I feel like mathematically we could make assertions about it, but that reasoning is less concrete than having absolute statistics from studied numbers. This is a good way through the door to have that component of the discussion becoming acceptable from a factual/evidence perspective rather than just conjecture.)


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You can’t throw a stick without hitting a JC-registered TB with line-breeding to Bay Ronald… especially through Bayardo, Gay Crusader, and Teddy…

Genuinely surprised to read this is the suspected source. You would think that if this was the case WFFS would be far more common in TBs.


I find it hard to believe either. If Bay Ronald/Dark Rohald were responsible, then the German TB should be affected about 50% of the time, given how prevalent and in multiples Dark Ronald is.

From the very beginning of the brouhaha, the Germans have been wanting to find a TB source.


Didn’t read it all, but it sounds like they’re jumping to conclusions.

Correlation does not equal causation.


I am okay with it being a TB source, if it makes sense; but I am scratching my head here because it would be much more common in JC TBs, and in German TBs, as you said. Just looking at my own personal TBs, I’m seeing Bay Ronald up to eight times in them, and they all have fairly commercial/standard pedigrees.

Where the JC is concerned, you can bet that there would be investigations into weird abortions and/or foals born with fragile skin - the JC takes reproductive health very seriously in my experience - it’s a huge part of their market. If this was a big problem in TBs, we’d have sources for it… and we don’t.

When you consider how influential Bay Ronald or Furioso were, I guess it makes sense someone sees a connection because it’s a familiar name… but it also makes very little sense, given there are stallions that have tested positive for WFFS that don’t have Bay Ronald, to my knowledge.

If you go far enough back in any WB, you’re going to find common ancestors… The WB breeding pool is very small once you start looking at ancestors from early 1900s / late 1800s. Just take a precursory look at a handful of WFFS positive stallions and you’ll see they share ancestors besides Bay Ronald.


Anyone know if the JC is doing WFFS testing?

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The thing that makes me doubtful is that the German TB has Dark Ronald through multiple sources–mares as well as stallions. Even if we assume that by some chance, the famous Bay Ronald line TB stallions were all negative, in Germany the Dark Ronald line is prevalent through mare daughters as well as sons and in multiples of both mares and stallions. Surely 50% of those would be carriers, and the German TB would be rife with WFFS.


Acatenango has Bay Ronald around ten times…

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I have a friend who had her TB mare tested as she is breeding to warmblood stallions. The mare tested as a carrier (Animal Genetics and U Cal Davis labs.) When she contacted the Jockey Club to see if they were testing the Tb population, they responded that they didn’t believe the allele exists.

So there is very limited data on the incidence of the allele in the Thoroughbred population. The origin is irrelevant in my opinion.



That is really bad!

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This is really interesting. I would be curious to know of the TB’s pedigree, if you have it.

RE: JC’s reaction, that is not good at all… did your friend respond with the positive documents showing the mare was tested as a carrier by both labs?

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Does anyone know if UC Davis has published any other sets of results besides what they released in May of 2018? “At UC Davis, 340 warmbloods have been tested, with 9% identified as carriers. Ninety-five Thoroughbreds have been tested; 4% are carriers. Forty-five Knabstruppers have been tested; 7% are carriers.”

It’d be interesting to see updated stats.

I’m wondering if TBs don’t carry affected fetuses to term as frequently, perhaps Warmbloods have another gene/modifier/allele (bear with me - not genetic expert) that interacts with the WFFS allele and results in the foals being carried to term? I do think that if TBs were born with this syndrome with even occasional frequency it would have been discussed more. But how often have we heard of mares being difficult to keep pregnant, etc? Before testing was available no one could possibly know that WFFS would have been a possible factor. I’m hoping whoever responded for the JC was misinformed/uninformed…

I’ll test my mare this year or next (no immediate breeding plans). Her sire is negative, dam was full TB.

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No, they are not. They told me why would they test for a “Warmblood disease” so I explained that there is Tb blood in the Warmblood population. Crickets…

A friend of mine came up with a very plausible reason as to why it’s not as prevalent in thoroughbreds as it is in warmbloods. A Tb mare on a racehorse breeding farm that doesn’t carry to term can cost the farm millions in potential losses. She propsed that Tb mares that did not produce were culled from the herd thereby inadvertently reducing the number of WFFS carrier mares.


I’m sure it’s a lot more prevelant than 4%. The problem is the JC does not acknowledge its existence so they are not looking for it. I wonder though with the potential for economic impact if they ever will. Ostrich syndrome


Any good breeder is going to cull mares that don’t carry to term. It’s arguably more likely for WB breeders to do so more quickly since most TB breedings come with a live foal guarantee. But until we know the percentage of TBs/WBs that are carriers we can’t even guess what percentage of breedings might be affected.