Page 136 - SPEEDHORSE April 2018

“I wanted to take the technologies being developed for human athletes and see if we could make them useful for helping select and manage racehorses.”
the other differences between these horses and then looked at who succeeded and who didn’t, the heart was the variable that made the difference.
“It’s no longer just a theory, but a proven technology,” he says.
Heart measurements can be one of many clues to racing ability. “For instance, American Pharoah has a phenomenal heart,” says Seder. “He was at the yearling sale at Saratoga when we looked at his heart. He was a beautiful
colt and everyone liked him, but he had a
cut on his ankle. Ahmed Zayat was thinking about selling him, but with the swelling Zayat ended up bringing the colt back home. Part
of our evaluation was to look at the hearts of these yearlings, so we did look at that colt and thought, ‘Oh, my,’ and we advised him to keep that horse.” American Pharoah went on to win the 2015 Triple Crown.
EXAMINING YEARLINGS AT SALES
Heart scanning is becoming more rou- tine at yearling sales. Miller compares it to having a human ultrasound. “If you need ultrasounds, they tell you to have the same technician do it each time and, if possible, the same machine. That’s the best way to have consistency. I am still dragging around this old machine, but it gives a very clear image,” she says.
Because it does the job so well, they searched for and bought every old machine
like it that they could find so they wouldn’t have to change to a different kind of machine, and now have about five of them. “All ultra- sound machines have distortions as you go deeper. Thus, it is very hard to compare heart sizes from two different kinds of machines. Ultrasound techs will tell you they become very comfortable with the machine they have, and they don’t want to keep changing,” says Miller.
“To be really good at cardiovascular mea- suring, a person also has to do a lot of home- work and know a lot about anatomy,” she says. “Horse’s hearts are all different and they aren’t always exactly in there at the proper angle. Veterinarians understand anatomy, but an ultrasound technician doesn’t unless they have spent a lot of time understanding what they are looking at. It helps to have done a lot of horses. The first few years I measured hearts, 20 years ago, I wasn’t as good at it.”
You also want to have someone who is
an expert at handling horses. “Patti was one of the first women jockeys and she’s been a racehorse trainer,” says Seder. “She and her handler for the horses we ultrasound have worked with racehorses their whole lives and that’s all they do. When they go into a stall to do a young horse for a sale, they are profes- sional and know how to keep that horse calm. You can’t just hire someone and send two people and an electrical machine in there with a yearling or you risk having a disaster. In all our scans, we’ve never had a safety issue.
“You can walk into a stall and the resting heart rate can jump from 30 to 120 beats
per minute if that horse gets upset,” explains Seder. “You may not be able to detect any outward sign, yet the heart rate jumps to four times the normal rate. So, you must have people who know how to not let that happen or else your data is no good.”
“You are walking into a stall with someone’s long-term investment,” says Miller. “You have to treat it like it is a fine instrument and be very careful with it. We take this very seriously.”
To make sure the horses are calm, they often do these measurements at night when there are fewer people around and less distrac- tion for the horses. “We’ll still do some during the day, but the problem is that we must go a lot slower,” Miller says.
“Anything that lowers blood pressure can change the accuracy of the exam because we are looking at the left ventricle at peak dias- tole,” she says. “Some people might tranquil- ize the horse so we can work on it, but that destroys the data. Anything that influences peripheral dilation or if the horse had a bad experience a few minutes before we come into the stall, it won’t be accurate.”
LOOKING AT QUARTER HORSES
Not many people are scanning hearts
of Quarter Horses for comparing potential racing ability, but hearts of running Quarter Horses have been examined in other ways.
“Precocious speed horses like running Quarter Horses generally have smaller, but very powerful, hearts,” states Bill Casner, Texas breeder of Thoroughbreds and Quarter Horses. “The size must be put into context with several other criteria. If the heart is
too big, however, it can act like a big bil-
low and not be able to contract with every stride, which becomes the limiting factor for distance.
“Every horse has his maximum cruising speed that he can sustain while being able to breathe with every stride. If a horse goes too fast, he will shorten his stride in the last part of the race.
“It has been said that horses can run 3/8 mile anaerobically, so I would suspect that Quarter Horses can easily run a 1/4 of a mile without going into oxygen debt,” Casner says. “Many Quarter Horses can run all-out from gate to wire, but some can maintain and gain speed late in the race. The reason for this may be having an optimum heart in combination with optimum biomechanics. The ultimate calculation would be measuring stroke volume of the heart, but that has yet to be done effec- tively in horses.”
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EQUINE HEALTH