Horse Racing Forum - USA Thoroughbred Races

I was reading about the large heart gene that some racehorses appear to have. Assuming that this can be detected by a scan, are foals actually scanned for this prior to significant sales (eg Keenland September). This could be useful information for all concerned.

Also do we know which leading sires carry the gene and which don't?

Thanks.

We don't scan our own foals but buyers will occasionally ask to do a scan at a sale, which we of course allow. So buyers who are interested in the information are able to obtain it.

I had no idea such scans were even done. You learn something new everyday!

frankel13 wrote:I was reading about the large heart gene that some racehorses appear to have. Assuming that this can be detected by a scan, are foals actually scanned for this prior to significant sales (eg Keenland September). This could be useful information for all concerned.

Also do we know which leading sires carry the gene and which don't?

Thanks.

Princequillo carried the gene, which is passed from sire to daughter to her offspring. So Princequillo passed it to Somethingroyal, who passed it to Secretariat. This might very well explain why both Princequillo and Secretariat were great broodmare sires while their male lines didn't have strong sires to carry on.

By the way, on his death at 23, a necropsy showed that Sham also had a larger than normal heart. His dam, Sequoia, was also by Princequillo. So you see, in and of itself, the large heart is no guarantee of wins on the racetrack. In both the Kentucky Derby and Preakness, Sham finished 8 lengths ahead of all the other horses except one. Secretariat finished 2 1/2 lengths in front of Sham. The Belmont forever separated these two maternal grandsons of Princequillo because there was some indefinable something remarkable about Secretariat that Sham didn't possess even though both colts had the large heart.

Ridan_Remembered, you're right to point out that a large heart is not guarantee of wins. It's not guarantee of anything really, nor even necessarily an indicator of desireable traits like systemic efficiency or superior ability. Actually an enlarged heart is one symptom of a diseased heart. So while there are certainly people promoting and making money off the "exciting discovery" of the large heart gene, there remain as many skeptics as there are believers as to how meaningful the testing really is.

Obviouly Secretariat heart was not diseased. The gene for a larger heart is simply a gene for a larger pump which carries more oxygenated blood to muscles . This decreases the latic acid concentration and therefore improves muscle performance. You are talking of cardiomyopathy which of course is a diseased heart.

I have often wondered why this matter has not been advertised by stallion managers.
Surely a vet should be able to determinate if a heart size is unusually big, shouldn't he/she? Some breeders would see that as a desirable trait to get it passed to their offspring and therefore it would make the sire more popular and profitable.
Why we have to wonder that trait is passed on just by studying pedigrees and guessing when a simple scan would assure us beyond doubt ?

LBM wrote:I have often wondered why this matter has not been advertised by stallion managers.
Surely a vet should be able to determinate if a heart size is unusually big, shouldn't he/she? Some breeders would see that as a desirable trait to get it passed to their offspring and therefore it would make the sire more popular and profitable.
Why we have to wonder that trait is passed on just by studying pedigrees and guessing when a simple scan would assure us beyond doubt ?

One stallion that has been advertised repeatedly as having a large heart is Kitalpha, giving breeders who are looking for that trait a stallion to take their mares to.

Most breeders think things like pedigree, performance and the ability to sire high class winners, are more important qualities to look for.

In her third book, Marianna Haun says there are two versions of the large heart gene, one passed down through Eclipse and one from the Darley Arabian (which is what Secretariat had). The Darley heart gene is passed with a skeleton that has one less lumbar vertebrae, which gives the horse a shorter back and longer stride.

She points out that when Secretariat was measured for a statue, the length of his legs from elbow to ground was 4 inches longer than the length of his back from withers to point of hip.

Of course Secretariat also had other attributes that made him a champion -- he had the lung capacity to support the heart and his gait, according to experts was nearly perfect, with very little wasted energy.

I think that the large heart is most useful to horses when racing at distances over a mile.

As an example, Verrazano was scanned as a yearling and had a normal sized heart. http://performancegenetics.com/wp-conte ... -2010c.pdf He won at distances up to a mile and an eight, but never won at a mile and a quarter.

aethervox

aethervox wrote:In her third book, Marianna Haun says there are two versions of the large heart gene, one passed down through Eclipse and one from the Darley Arabian (which is what Secretariat had). The Darley heart gene is passed with a skeleton that has one less lumbar vertebrae, which gives the horse a shorter back and longer stride.

She points out that when Secretariat was measured for a statue, the length of his legs from elbow to ground was 4 inches longer than the length of his back from withers to point of hip.

Of course Secretariat also had other attributes that made him a champion -- he had the lung capacity to support the heart and his gait, according to experts was nearly perfect, with very little wasted energy.

I think that the large heart is most useful to horses when racing at distances over a mile.

As an example, Verrazano was scanned as a yearling and had a normal sized heart. http://performancegenetics.com/wp-conte ... -2010c.pdf He won at distances up to a mile and an eight, but never won at a mile and a quarter.

aethervox

that is really interesting, I really don't know anything about large hearts in thoroughbreds but this is a very useful thread!

Complete nonsense.

If it worked everybody would not just want to do it, they'd have to do it. It doesn't, so they don't.

tonno100 wrote:Complete nonsense.

If it worked everybody would not just want to do it, they'd have to do it. It doesn't, so they don't.

I don't think that's entirely fair. As has been mentioned, it's only one factor out of many that make up a successful racehorse - length of stride, soundness, courage, size. Plenty of horses succeed without one of the aforementioned factors in their favour. The question is whether it's advantageous, and there's plenty of evidence that it is.

When it's discovered upon his death that possibly the greatest racehorse of all time (Secretariat) had a heart almost 3 times larger than the average thoroughbred then questions should and have been asked. From what I can see nothing has been proved nor disproved, but if I was lucky enough to be able to afford to race or breed these fantastic animals then I'd be all over this theory like a rash. It gives the opportunity to acquire a nice animal(s) at a price that may be unthinkable in a few years time if the link is proven.

A recent article I found on this is shown below:

http://www.pedigree-dynamics.com.au/x-m ... ne-theory/

frankel13 wrote:When it's discovered upon his death that possibly the greatest racehorse of all time (Secretariat) had a heart almost 3 times larger than the average thoroughbred then questions should and have been asked. From what I can see nothing has been proved nor disproved, but if I was lucky enough to be able to afford to race or breed these fantastic animals then I'd be all over this theory like a rash. It gives the opportunity to acquire a nice animal(s) at a price that may be unthinkable in a few years time if the link is proven.

A recent article I found on this is shown below:

http://www.pedigree-dynamics.com.au/x-m ... ne-theory/

I read the article. It's interesting to me that the author used Eavesdropper as his example of a horse with the "coveted" Large Heart Gene. Eavesdropper was only moderately successful as a racehorse and he was a failure as a sire in the U.S. (35% winners, 0% stakes winners.) So what was his LHG supposed to have helped him with?

TBird, I only included that link because it was recent (written a month ago). For me a more interesting article is shown below;

http://www.horsesonly.com/crossroads/xf ... eart-1.htm

I just chanced upon this topic whilst browsing the web and found it interesting. Is it positively talked about in breeding circles, treated as mumbo jumbo or not discussed at all?

If I have read correctly, the Large Heart Gene possessed by Secretariat is passed through the daughters, which may be one reason Big Red ended up being a really good broodmare sire. So, perhaps it would be worth following Eavesdropper's daughters to see if he also has success there?

There are plenty of people scanning hearts, and they have no more success than anyone else. In fact, I can't think of any really top buyers who do it, but they still get out a higher % of stakes winners than the heart score nuts.