Can Breeding Play a Part in Horse Racing Injuries?

September 13, 2023

Photo: Ernie Belmonte/Past The Wire

Is Horse Racing Asking All the Right Questions Regarding Fatalities in the Sport?

Is Horse Racing as an Industry Looking At Everything They Should Be To Curb Injuries in Thoroughbred Horse Racing?

By Laura Pugh

After two nationally televised breakdowns at Saratoga, and the moving of the Churchill Downs meet, all the powers that be in Thoroughbred racing can do is scratch their heads, tell us it is part of the sport, and they are looking into it. Are they? Is that enough? Are they looking at everything they should and could be?

I have my own thoughts and theories on that and this is one of them.

They move meets, make track safety advisory boards, and talk of ripping out the dirt for synthetics, which happened once already and failed due to their bases crumbling apart far faster than they should have, all with no proof at all that the track is the actual issue. 

As always, racing would rather focus on the non-issue, which distracts from theories that could very well be right, but cost them everything, leading to what I view as the ‘breeding to break’ culture. It is important to note, commercial breeding is a business as is horse racing. Breeders will breed what sells and what is in demand.

What are these theories you might ask? Firstly, the problem starts in the breeding shed by breeding lines that have genes that cause slower bone remodeling than others. Secondly, in order to get a quick return on investment (ROI), these same horses are exposed to too many therapeutic medications that mask their symptoms, instead of the connections backing off and giving the horse, and their bodies the proper time to heal. 

Bad Blood

During the Churchill Downs meet, I wrote an article for Past the Wire, titled Are Synthetic Tracks the Answer or the Reaction. In that piece I go through the pedigrees of nine of the, at that time 12, horses that died to catastrophic breakdowns. It was then that I noticed a pattern. 

Seven of the nine had several connections to Mr. Prospector, a sire known for his speed, but who retired with a fractured sesamoid, and reportedly passed along conformational defects to his progeny according to the site American Classic pedigrees. Of those seven, five had connections to the Mr. Prospector son Fappiano. 

As of the writing of this article, there have been 205 catastrophic breakdowns. 45 of the horses that have broken down feature crosses where Fappiano is part of the sire or broodmare sire line. That equates to roughly 22%. To see if that was normal for that line, I made a list of 200 horses that had retired without significant breaks. This list was made up of retired standing studs, fillies and mares from the 2022 Keeneland November breeding sale, along with mares and geldings that had been retired to accredited Thoroughbred Aftercare Alliance facilities.

That list showed 34 horses that had crosses to Fappiano, which comes to 17%. 

Click on chart to enlarge

Upon examination of these pedigrees, I noticed that while Fappiano’s blood was showing up, the reason it was showing up so frequently was because of a specific son… Unbridled.  

“He had a massive build inherited from his broodmare sire, Le Fabuleux. His forelegs were poorly conformed, particularly the right, which turned out markedly,” is what American Classic Pedigrees had to say about the son of Fappiano, who was noted as pigeon-toed with offset knees. 

Of the Fappiano crosses from the breakdown group, 90% came from Unbridled, over half of which came from Unbridled’s Song. For those unaware, Unbridled’s Song was plagued by injuries and illness throughout his career and was eventually retired due to a fractured cannon bone. 

Another, smaller chunk, came from Cryptoclearance, by Fappiano, retired due to a torn ligament. His son Victory Gallop also retired with a ligament injury. Candy Ride, a grandson of Cryptoclearance, and his son, Twirling Candy also retired to ligament injuries. Thing is, there have been studies that show even ligament issues can be hereditary, which could very well explain why we’ve seen Candy Ride, the grandson of Cryptoclearance, and his son Twirling Candy retire with ligament injuries. 

Another son of Unbridled retired after injury was Grindstone. Grindstone, on the other hand, like Unbridled and Unbridled’s Song, retired with a bone chip in his knee. He also had a chip in his ankle, after only two starts as a juvenile, which caused him to miss the rest of that season. His son, Birdstone also retired after a bone chip was found in his ankle, and Summer Bird, a son of Birdstone, was retired after a fracture to his cannon bone was discovered.

Click on chart to enlarge

Four horses on the breakdown list feature this line in their pedigree cross. Two of which sustained ankle fractures and were euthanized on the track. One is listed as “suffered a catastrophic injury and was euthanized on track”, while the fourth broke both front legs. 

Another link to Unbridled, but not found through a son of his, can be found through another prominent sire, Tapit. The mother of Tapit, Tap Your Heels is a daughter of Unbridled. When examining crosses that descend from an A. P. Indy sire line, 16 out of 47 were from Tapit sons. Of the 15 did not involve a direct sire or broodmare sire line with Unbridled, giving Unbridled 53 Representations from the horses found in the sire or broodmare sire lines, meaning nearly 26% of the 205 were found with Unbridled Blood. 

Click on chart to enlarge
Click on chart to enlarge

When compared to the Control Group, out of the 33 Fappiano lines, 23, or 67% were tied to Unbridled. Quite a bit less than the 90% from the grouping that suffered catastrophic injuries. There were also just 10 horses with a sire or broodmare sireline form Tapit, which equates to just 16.5% of the control group being represented with Unbridled blood in their crosses. 

“You’ve got some really important stuff,” said pedigree analyst Jessica Tugwell. “I think pedigree tracking needs to be done alongside all the other risk factor tracking and is just as important. Trainers have plenty of anecdotal evidence about the durability of certain bloodlines, and the industry should take studying that as seriously as factors such as track surface.”

Click for Sons and Crosses Analysis

Tracking? What Tracking?

Speaking of tracking this data, it seems as though the industry, which has the Equine Injury Database (EID). If you are wondering what the EID’s job is, here is what it was specifically created to do… 

“The Equine Injury DatabaseTM is the Thoroughbred industry’s first national database of racing injuries. Launched by The Jockey Club in July 2008, the Equine Injury Database seeks to:

identify the frequency, types and outcome of racing injuries using a standardized format that will generate valid statistics. Identify markers for horses at increased risk of injury. Serve as a data source for research directed at improving safety and preventing injuries.”

You would assume that pedigree would be something that would be investigated as a marker, especially where there are several studies that show fractures and even soft tissue injuries can be hereditary. However, that isn’t the case.

When asked if the EID tracks the names and pedigrees of the horses that have suffered catastrophic injuries, Shannon Luce the Director of Communications for the Jockey Club said this, “Reports submitted to the EID do not contain this information.”

However, in an interview with the Paulick Report, Dr. Tim Parkin, the primary epidemiologist who analyzes data from the Equine Injury Database, said that the sire and dam were inserted into the multivariable analyses as “random effects.” 

“It means we account for any sire/mare effect without generating a specific odds ratio (risk) for each sire or dam.” Said Parkin.

In his Paulick Report interview, Parkin went on record saying that, according to his models, he didn’t believe that the sire and mare made much difference in the impact of breakdowns. He even went as far as to try and dismiss two studies from Great Britain and Hong Kong, from 2013 and 2014, that supported the hypothesis that fractures, and soft tissue injuries are hereditary. 

When asked by this writer about two other studies from 2020 and 2021 that had linked certain genes and their expressions with an increase in fatal injuries, Parkin said this “This is getting beyond my level of expertise wrt (with regards to) the genetics.”

Parkin also admitted that, to his knowledge, that the pedigree data that is used in the EID doesn’t go beyond sire and dam. “We do not, I believe, have any deeper pedigree that we use when modeling.”

The EID is far from perfect, and this is something that Parkin alluded to in an interview with The Horse Magazine in 2019. The model, as is, only has the ability to explain 35% of the trends in breakdowns. According to Parkin, it could be a lot higher if certain holes were filled. 

“If we knew exactly what every horse experienced on every day of its life (nutrition, training, veterinary history, treatments etc.), I am sure our models would be much more predictive,” Parkin told The Horse. 

The question here is, how do you track this data if it’s not made public, and the tool used to identify markers for horses at increased risk for injury doesn’t make it available, either… The answer is Freedom of Information Act (FOIA) requests, which is what the website Horse Racing Wrongs does to gather the names of all the fatalities of racehorses across the nation.

In order to build the statistics above, I had to go through the list of horses that had died in 2023, and then check them against Equibase and Pedigree Query for accuracy. Once completed, I went back through the pedigrees and noted the sire, dam, damsire, coefficients of inbreeding, and the specific sire/broodmare sire crosses. 

The sample size was small, admittedly, but what can be expected when this isn’t something that is being tracked?

Tugwell, who was also searching for a database that might track pedigree after the recent fatalities of Maple Leaf Mel and New York Thunder, also came up empty pondered the reasoning for not tracking pedigree.

“The way things are right now, there’s anecdotal evidence about which lines have which issues…Buyers can form their own opinions and make decisions based on their experience, but it doesn’t really affect the bottom line as far as the stud farms are concerned. It’s just personal preference, the free market at work,” says Tugwell. 

“But if the Jockey Club or HISA comes out with indisputable evidence (or worse, disputable evidence) that horses by Z are, say, 10% more likely to experience a catastrophic injury, well now you’re risking seriously hurting the value of Z’s offspring. If you say that crossing Z with X created an even greater risk of injury, well, there are plenty of X mares who would normally be in the mare pool for Z who are no longer viable.”

Click for Copy of Breeding Flaws Spreadsheet

What the Studies Say

The studies mentioned in the piece by the Paulick Report aren’t the only studies that have investigated the heritability of catastrophic breakdowns. Several studies have found links between catastrophic breakdowns and genes within the 18th chromosome, often called “the speed chromosome.”

A study in 2014 by Sarah C. Blott found that “Significant genetic variation for the fracture risk in the Thoroughbred racehorse was detected on chromosomes 9,18, 22, and 31…In a related genome-wide association study SNPs on chromosomes 1 and 18 reached genome wide significance.” 

Another study in 2019, further investigated the link between breakdowns and chromosome 18, going so far as to isolate the expression of the COL3A1 gene. 

“In support of previous work identifying the fracture associated region on ECA 18 (Blott et al. 2014; Tozaki et al 2020) we demonstrated that one of the genes in its region, COL3A1, is differentially expressed in cells from horses at high and low risk of fracture and that this may be due to the presence of an associated SNP in the COL31A promoter. 

In addition to those studies, there is a completely separate one, published in 2021 focused on the expression of mRNA to detect changes in select genes to determine which were most at risk for catastrophic injury. 

This study revealed three different genes than the previous studies. According to an infographic for this study, the three markers combined, correctly identify horses at risk for catastrophic injury 76% of the time. These genes were IGF-1, which increased in the injured horses due to chronic inflammation; MMP2, which increased due to bone damage; and IRAP which decreased in the catastrophically injured due to chronic inflammation. 

A follow up on the last study is currently being conducted, which according to investigator, scientist Dr. Allen Page, should be concluded in 2024. 

Contributing Authors

Laura Pugh

Laura Pugh

Laura Pugh got her first taste of Thoroughbred racing when she watched War Emblem take the Kentucky Derby and Preakness Stakes in 2002. At that...

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