Bleeding and Genetics

[Joltman]

This article is very telling -

http://www.bloodhorse.com/horse-racing/ ... n=20110616

That bleeding is passed on genetically and that bleeders should be removed from the gene pool. It mentions how South African and German associations have protected the TB gene pool by removing bleeders from stud duty. Some questions it raises for me are:

- Is it true? Is it supported by other studies?
- If so, what sires and sire lines are the worst offenders? (anyone know Mandela?)

Proposed 'no race day meds' regs would start reducing these lines by attrition.

So maybe the German lineage of Animal Kingdom raises his value as a sire all the more?

jm

(PS - if this was discussed elsewhere plz append to that discussion)

[Kari]

I downloaded the study & went through it. Here's my understanding of it.

The study was done on 63,000+ horses that raced between 1986-2002. Age, sex, distance raced, altitude of the race being ran, weight carried, month that the race was run, and racing surface were all taken into account. Each variable was given a numeric value based on an algorithm (that was waaay over my head- calculus is a weak spot for me! ).

There were 1,471 sires noted in this study. Out of those sires, 354 of them produced a horse that bled after the race. Each stallion was assigned a fixed number based on the probability of producing a horse that bled under certain conditions. Those numbers were averaged to determine the most suspect sires. This ensures that mere percentage of bleeders produced does not mean a stallion is more likely to produce a bleeder.

According to the study, these were the top 5 stallions in South Africa that produced bleeders:

Print (GB)- 101 horses raced, 11 horses that bled
http://www.pedigreequery.com/print
Lost Chord (GB)- 275 horses raced, 17 horses that bled
http://www.pedigreequery.com/lost+chord2
Al Mufti (USA)- 284 horses raced, 21 horses that bled
http://www.pedigreequery.com/al+mufti
Folmar (USA)- 380 horses raced, 21 horses that bled
http://www.pedigreequery.com/folmar
Northern Guest (USA)- 817 horses raced, 46 horses that bled
http://www.pedigreequery.com/northern+guest

I'm hoping that the AAEP puts together a similar study on horses here in the US (and not just because I'd love to get in on it!). When you look at the pedigrees of these top 5 sires, there are some VERY familiar names that jump out.

[Linda_d]

It has always made sense to me that breeding a horse that bleeds is likely to increase the chances of getting another horse that bleeds because bleeding is based on a horse's physiology -- which results from his genetic makeup.

[Joltman]

I downloaded the study & went through it. Here's my understanding of it.

The study was done on 63,000+ horses that raced between 1986-2002. Age, sex, distance raced, altitude of the race being ran, weight carried, month that the race was run, and racing surface were all taken into account. Each variable was given a numeric value based on an algorithm (that was waaay over my head- calculus is a weak spot for me! ).

There were 1,471 sires noted in this study. Out of those sires, 354 of them produced a horse that bled after the race. Each stallion was assigned a fixed number based on the probability of producing a horse that bled under certain conditions. Those numbers were averaged to determine the most suspect sires. This ensures that mere percentage of bleeders produced does not mean a stallion is more likely to produce a bleeder.

According to the study, these were the top 5 stallions in South Africa that produced bleeders:

Print (GB)- 101 horses raced, 11 horses that bled
http://www.pedigreequery.com/print
Lost Chord (GB)- 275 horses raced, 17 horses that bled
http://www.pedigreequery.com/lost+chord2
Al Mufti (USA)- 284 horses raced, 21 horses that bled
http://www.pedigreequery.com/al+mufti
Folmar (USA)- 380 horses raced, 21 horses that bled
http://www.pedigreequery.com/folmar
Northern Guest (USA)- 817 horses raced, 46 horses that bled
http://www.pedigreequery.com/northern+guest

I'm hoping that the AAEP puts together a similar study on horses here in the US (and not just because I'd love to get in on it!). When you look at the pedigrees of these top 5 sires, there are some VERY familiar names that jump out.

Thanks Kari, an AAEP study would be so helpful. (and I'm sure, unpopular - condemned in some corners). This is one of those things that a pedigree statistician could bring some light to. One thing I noticed is that Buckpasser on the BM sire side came up in a couple. Also, strangely (?) a couple of sires who were more known for distance aptitudes popped up. Could it be that these were placed in sprints which pushed their genetically set physiology over the top at high speed sustained, resulting in bleeding? If so, then the practice of 'racing a horse into shape' may be bad for horses bred to go long.

jm

[jellac]

Joltman observed:

One thing I noticed is that Buckpasser on the BM sire side came up in a couple.

This report should concern all of us involved with thoroughbreds for racing - as breeders, trainers and conditioners, as bettors and as fans. However, I would also hasten to caution against using the reported results of this study to make suppositions/alternate conclusions than those which the study has drawn. Namely that it found a statistial relationship between certain sire(s) and bleeding during/after a race and furthermore characterized that relationship as being 'strong' not anecdotal or incidental. To now begin questioning the influence of individuals further back in the pedigree is to go way beyond the data originally collected/presented here. That is not the linkage which this study has made in its reported results While they may make something of a contribution this study in no way documents or delineates that and wasn't designed to do so. Rather it took note of the sires of horses that were observed to bleed along with several other factors such as altitude of the track, the length of the race, etc. and found a strong statistical relationship between certain stallions as sires and the propensity for bleeding among the population of racehorses observed. It doesn't say that you won't get bleeding after a race from a horse bred by a different sire just that you are much less likely to under the observed conditions. It certainly doesn't provide any scientific basis for questioning the multitude of genetic contributors further back in the pedigrees - so far the link is one of sire to bleeding propensity.

I would be very much in favor of seeing N. American tracks adopt the post-race 5 minute walking ring procedure for all entrants before the track vet so that exercise induced bleeding can be observed and having that data recorded, statisticly computed as was done in the S. African study with annual updates to those statistics and I would like to see race day medication such as Salix (BUTE) etc. be discontinued. Then - perhaps when a racehorse is observed to bleed (as opposed to having a scope put down his nostril to see if there's just the tiniest bit of blood in his deep lungs) post-race that individual can get permission to take Salix for his/her racing career but it will be public knowledge for breeders to take note of. In such manner I believe that you would see a rather steady yet gradual cycling away from breeding to the successful yet prone to bleed stallion or perhaps even his immediate sire......

[Joltman]

good points. If the supposition that there is a sireline relationship, who's to say there isn't a broodmare sire line relationship. Not that this data points to it, but sometimes coincidences point to real relationships that can be measured and all those who dive into the such a pool of data might well simply look at another part of the pedigree. It could be that a 'bleeder sire' might not have any effect as the broodmare sire, or perhaps less of an effect. It would also be interesting to see if dilution takes place after a couple of generations or if it remains in the sire line.

I know that if I stood a stallion and could assert that he is less likely to have his get have breeding problems I would publicize that big time~

But what is very good about this study (and what needs to follow) is a better understanding of bleeding and performance and its relationship to pedigree. One final factor of interest would be a correspondence of bleeding data to Airflow measurements, the thought being that limited airflow might seem to make a horse prone to bleeding.

With more of this info, we can all breed better horses that are less likely to need Salix or anything else.

jm

[Dave C]

I think we have to be very careful about jumping to conclusions here.

Firstly, in jurisdictions where bleeding is taken very seriously, trainers and grooms become very good at covering it up. The horses that were detected may have just been in the care of trainers less careful about covering it up or less concerned because it was only a cheap horse anyways.

Secondly, they did not control for all variables. Variables such as incidents of respiratory infections as young horses can be contributing factors to bleeding, but was not controlled for in this study because the information is not available. The breeders would be no more interested in disclosing this information to potential buyers than trainers are to disclose a horse bleeding to stewards who could rule the horse off.

There are a myriad of human factors that must be controlled for before we can start concluding that genetics are a major or even significant contribution to bleeding.

[Kari]

The study only took into account environmental and genetic factors of the horses that raced. The horses aren't scoped at the track post-race, so "internal bleeding" wasn't identified. All of the horses noted as bleeders were observed with a nosebleed post-race by a veterinarian.

One factor that really caught my eye was the elevation of some of the tracks in S.A. Four out of the 8 listed in the study were about 2000m above sea level.

I'd love to see a similar study done on another group of horses in a different population.

[Joltman]

this kind of study is good in that it postulates some conclusions based on its data, but the real test is whether it is repeatable in other populations.

I would find it reasonable that just as other physiological factors can be inherited, so also bleeding tendency.

jm

[xfactor fan]

First drop the idea that it is a sireline problem. The equine Y chromosome doesn't have a lot of genes on it, and most horses now carry the same Y they got from the Darley Arabian. Not many Beyerley Turks, or Godolphin Arabian Y's around any more.

That means it is likely to be one one of the non sex chromsomes. And it's most likely either recessive or multi factoral. Or there could be several causes that produce the same end result--post race bleeding.

Anyone like to conside that bleeding could be caused by horses being pushed beyond their level of fitness?

[madelyn]

It has also been determined that Salix, as a diuretic, causes race day weight loss and gives a horse an advantage. The problem with isolating the bleeders only for medication is that it might actually cause them to win more often, having the opposite effect since people breed to win.

[griff]

Jellac

did I understand corrrectly that you propose to make public knowledge of the usw of salex by any race horse??

griff

[madelyn]

The use of Salix IS public knowledge. It is in the racing form and race program.

[BenB]

I have screamed it for more than five yrs, bleeding is all about genetics.

The use of salix and lasix are undermining the breed as a whole and nothing else.

[Dave C]

I have screamed it for more than five yrs, bleeding is all about genetics.

The use of salix and lasix are undermining the breed as a whole and nothing else.

Are you prepared to argue that emphysema in humans is all about genetics?

I've read very good physiological studies which show that small airways disease can be and may be the leading cause of EIPH. Small airways disease was shown to cause bleeding by causing asymetric inflation of the lungs causing pressure differentials to arise resulting in blood vessel ruptures. Small airways disease can be the result of genetics but it can also be the result of injury such as previous incidences of EIPH, over exertion, infection, or irritation from dust.

If bleeding was purely genetic one would expect that those sires who were known to be bad bleeders as race horses would not produce successful international racehorses that do not race on lasix/salix.