The genetics behind a thoroughbred’s race to victory

What is it about the thoroughbred that stands the breed apart from others? The ‘speed gene’.

It was absolutely stunning news Friday when it was announced Canadian-owned thoroughbred  I’ll Have Another not only wouldn’t run in the Belmont Stakes but was retired from his racing career. He has the start of tendonitis in his left front leg. Tendon injuries heal over time but the tendon may not always recover to its former strength, compromising chances at elite racing success. Sometimes a tendon issue may heighten the risk of catastrophic injury.

The colt’s career earnings though have only just begun. With the Kentucky Derby and the Preakness wins under his saddle and with a Northern Dancer pedigree, his stud fees will soar and he’ll earn far more as a breeding stallion than he’ll ever earn accumulatively in racing. If he stands at stud for just, say, $100,000 and he covers 40 mares a year that’s an annual $4 million. And that’s hugely conservative in both fees and mares covered. He could have 15 years at stud so do the math.

For Mexican-born Canadian jockey Mario Gutierrez, who raced at Hastings Race Course for six years, he already has star power. There’s plenty of time for him to mount another great horse, perhaps even an offspring of I’ll Have Another.

What is it about the thoroughbred that stands the breed apart from others? The ‘speed gene’.  And a little Shetland mare that started it all.

Genetic scientists at the University College Dublin have traced the origin of the speed gene in Thoroughbreds back to a single British mare that lived in the U.K. around 300 years ago. Their research appeared in the science journal Nature Communications.

“The Shetland represents just one of many local British horse types which, according to historical sources, were highly prized for their racing ability before the Thoroughbred was formally established,” explained Dr. Emmeline Hill, genomics scientist at the UCD School of Agriculture and Food Science. “We’re not suggesting that Shetlands were speedy in themselves but rather that their genes, that are shared with ancestral populations, have made a key contribution to the Thoroughbred. Our results strongly suggest that the speed variant (C) of the myostatin gene (central to the control of muscle mass) entered the thoroughbred gene pool only once, around 300 years ago, and is likely to have come from a British native mare.”

The data showed that the highest frequency of the C-type speed variant gene from the DNA of nearly 1,000 horses from many breeds that were screened was among the Shetland population. Then, in analyzing the modern day expansion of the original speed gene, the scientists traced all the modern variants to Nearctic and his colt, legendary Canadian-bred Northern Dancer who, like I’ll Have Another, won the Kentucky Derby and the Preakness Stakes.

And that’s where I’ll Have Another’s pedigree kicks in and where his genetics for speed seem to have really aligned. He has inherited the genetic qualities of the speed gene of Northern Dancer from both his sire (Flower Alley) and dam (Arch’s Gal Edith).  He will stand to pass that heritage on to his offspring.

Friday was a brutally emotional roller-coaster for the colt’s owner, J. Paul Reddam, trainer Doug O’Neill, Mario Gutierrez and their families and staff, not to mention horse racing fans and the thousands who have tuned into this sport to follow the colt’s career.

I’ll Have Another knew how to get to the finish line. He was chasing a piece of history. But in the vagaries of this sport, all it takes is a knock, a bobble, to change outcomes, shift odds. The horse’s greatness is in his genes and he may yet still chase the Triple Crown in the flying hooves of his progeny.