Literally Dissecting Thoroughbred Performance

Not for the weak of heart, this post and accompanying video highlights the dissection of a racing thoroughbred, showing what physiological structures under the skin contribute to high class performance.

The link above is to the full video, nearly 45 minutes in length from a program called ‘Inside Nature’s Giants’. If you want the notated version, read below where I document the time (minutes:seconds) in the video with what is going on – and skip to whatever piece holds your interest.

0:50 – first brief shot on dissection table, turn away if you just ate and have a questionable constitution

2:22 – view of the Eclipse skeleton at Royal Veterinary College, wow. Owner wanted him dissected in 1789 to find out why he was so dominant.

3:30 – actual post mortem dissection begins in detail, what did I have for lunch again? I can watch NBA and NFL players get hurt in all kinds of gruesome ways, but I must turn away when a horse goes down on the track, it’s the abject fear and confusion that gets to me. Here the doc talks about typical external characteristics such as long legs, big eyes and ears, as well as biomechanics – while also touching on the ‘flight or fight’ response at the 5:00 minute mark.

5:30 – we notice the thoroughbred has no collarbones, arms are attached to the body solely by the shoulder musculature.

6:00 – tracing the evolution of the horse, we discover that they used to have 4 fingers, as opposed to just one middle finger, albeit 65 million years ago.

7:00 – longer limbs + fewer bones = faster horses able to evade predators

7:05 – out comes Mr. Scalpel, this is about to get even more interesting from my perspective.

9:00 – Photographers in England many years ago realize that at some points during a gallop, the entire weight of the horse is bearing down on a single leg. Biceps muscles exposed as the primary protagonist in the stride movement, flicking the front leg forwards, much like a catapult.

10:30 – super slow mo of a skeletal horse in stride

11:30 – wild horses were domesticated 6,000 years ago

12:00 – onto stud farm at Coolmore Ireland

13:15 – we see Yeats – 4x Ascot Gold Cup winner, trained by Aidan O’Brien who was quoted in a London newspaper about his superstar: “You would not believe how well he works at home. We have a heart monitor on him all the time, and his heart rate goes up and down very quickly. He’s not just a plodder, he’s unique. His lungs and his heart are massive. Most horses are full out at a mile and a half but his heart rate is just getting up to a 180 at that point and he is just getting going.”

Hmm, one of the world leaders in the industry, Coolmore, and their trainer is already looking at the insides of his horses during training at Ballydoyle. I have a feeling he is of the same mindset regarding So You Think (NZ), and I hope he brings him over to CD for the Breeder’s Cup next month.

14:00 – breeding shed time with Yeats and a lucky lady – he gets to do that 5x a day?

15:50 – back to the dissection table, where a leg is detached and placed into a press to illustrate the forces suffered during a gallop on the cannon bone and associated tendons, doc says the equine tendon is 20-30% more efficient at storing energy than a steel spring.

18:35 – want to see a blown tendon up close in the lab? It pops like a firecracker – but remember that outside of the lab, bones and tendons are alive. Somewhere, sometime, a researcher took a dead leg from a horse, put it on a machine like this to emulate racing stresses, and proudly proclaimed that horses only had a limited number of stride cycles in a lifetime before injury was to occur. Trainers ran with this and began the fashionable ‘less is more’ philosophy of conditioning. But in that ‘study’, the leg was dead – live bones constantly remodel to become stronger, and live tendons become more flexible in order to withstand racing pressures, with appropriate conditioning of course.

19:50 – for us Americans who don’t see the jump races around the world, this quick frame shows how much tougher those competitions are when a horse lands from a jump at the Grand National, a race infamous for its casualty rate which is quoted here at 2 fatalities per 1,000 starters. What!?! American dirt horses break down more often than that according to the latest Jockey Club statistics at 2.14 per 1,000 starters. Don’t let PETA get a hold of this fact.

20:10 – back to Eclipse and measures of biomechanical efficiency, we find him merely as ‘famously average’. I don’t believe this should be understated. He had no massive heart, he had no overly long legs or a huge throatlatch, etc. – he was simply perfectly put together with no weak, or strong, link. He would have been a $40k auction purchase in 2011 and he would have scored in the 99th percentile on my V200 testing.

21:30 – oh boy, the bone saw reveals cross section of equine lower leg, specifically the coffin bone – farriers should love this part

23:00 – shoeing explained and demonstrated

24:45 – back Inside one of Nature’s Giants (the name of the show) to the part I am interested in: the mechanism of massive oxygen delivery to working muscles

25:10 – respiratory system dissection, but first intestines in a chock-full state are removed – holy cow are they huge. Equine ribs number 18 vs the human 12.

26:35 – the massive lungs are filled much like a balloon (respiration rate during a race? 140x/min, or over 2x per second!) It takes these lab technicians with a big hose over a minute to fill up the lungs fully. And the lungs are 6 feet away from the nose.

28:25 – During a gallop each stride is tied to each breath – called ‘locomotor coupling’.

28:45 – we see how the intestines of the horse sit behind the lungs, and move to facilitate breathing during a gallop. A horse during a race moves as much oxygen in that 2 min as a human does in 24 hours. This slamming of the entrails inside the abdominal cavity is also thought to contribute to bruising of the lungs.

30:30 – Newmarket gallops: 70+ trainers, 2500 horses in training

31:00 – we meet trainer Mr. William Haggas to learn what he LOOKS for during training to identify a potential winner

31:30 – Mr. Haggas states, whether they cost $5mil or $5thou, no one can see inside their heart to ascertain whether or not they have the ‘stuff’ to win

32:30 – the dissected larynx – voicebox, the gateway to the trachea – which is the windpipe itself

34:15 – dynamic endoscope for problem breathers

34:07-34:17 – see that big, grey brick-like device on the male handler’s right wrist? That is a human Garmin HR/GPS device, which can be adapted for equine use. Thoroedge specialty! Hope they use this later-

34:30 – the vet in attendance states the overriding concept of Thoroedge: ‘anything good or bad for performance in a horse, happens chiefly at racing speeds.’ As a buyer of bloodstock you are often limited to measures taken at rest such as conformation or heart size, but as an owner/trainer/breeder – you simply MUST take advantage of your access to the horse during sales prep or conditioning and gather internal data such as HR and blood lactates, as this is your competitive edge.

Great vet insight here: why use a treadmill for this scope? Horses don’t race on treadmills – they race over ground with someone on their back, so let’s use a portable scope for this test.

34:45 – we see the portable scope for the first time

35:08 – we see the picture of the throat provided by this device

35:30 – live pics inside the horse’s airway on the gallops

35:45 – during gallop, horse sounds fine with respect to breathing

36:10 – we go uphill, horse is asked for a bit more – device shows problems with soft palate at top exertion – detail and frozen screen image at 37:00

37:15 – when palate displaces, oxygen supply is cut off, and performance suffers

38:30 – Phar Lap aka ‘The Red Terror’. Melbourne Cup winner kicks off discovery of the larger than normal heart and its effect on performance.

39:00 – the equine heart, dissected – as big and heavy as a bowling ball – comparison of HR in humans vs horses: Horse at rest 25bpm; human 50bpm. Horse at max effort 240bpm, human 185bpm. Horses jump from 24 to 240bpm in 9 sec, while humans take 90sec to move from 50 to 185bpm. (not in video, this is a Thoroedge aside)

41:20 – the heart gets a lot of play these days, but here we are introduced to the unique features of the equine spleen. Read more here about the spleen and it’s role in EIPH:

Splenic contraction due to adrenaline response differentiates between predators (humans) and prey (horses)

42:15 – hind end musculature dissection – uphill gallops on the training track develop this area to perfection. So does starting from the gate.

43:00 – the auction ring at Tattersalls, where we see how tough it is to pick a potential winner while merely watching them walk.

44:20 – the Equinome ‘speed gene’ – heard this presentation recently at the 2011 Bloodhorse Pedigree, Genetics, and Performance Symposium. I believe that already there are a few Kentucky Derby winners who did not possess the genetic makeup of a stayer. This theory was the hot topic of discussion last month, if you were not in attendance the Bloodhorse will put out the DVD at some point this winter for purchase.

One last comment from myself with regards to the practice of ultrasounding hearts. The amount of blood provided by the heart during exercise is called Cardiac Output, and is the product of Heart Rate and Stroke Volume. Stroke Volume itself is the product of Left Ventricular Size and Ejection Fraction.

The heart score people have nailed the Stroke Volume portion of the equation to perfection, but what is not captured is the maximum HR during exercise. This number varies from 203 to 240+bpm.

Even regally bred horses with multiple G1 winning parents can produce offspring with a max HR value capped at 203bpm – and these will never break their maidens, and are much more likely to get injured during the training process. If this is happening to your stock, you need to know ASAP – before spending $50k a year in upkeep/training costs for a horse that cannot win because he doesn’t possess the necessary raw materials.

Ok, we see all the internal organs and systems that lead to a winning racehorse, but how to determine if they are present without having to open them up after death? HR/GPS/lactate during exercise is the key.

Do you really think that observing behavior such as appetite, coat, ears, and whatnot is the ONLY sign of health and/or fitness in a horse?

Do you believe that all great horses share similar conformation traits that are visible on the outside, but their insides aren’t similarly distinguishable?

Consider: when something goes wrong with a horse, be it illness, infection, or injury – the very first response is to increase blood flow to the affected areas in an effort to remedy the situation. This can be measured by observing heart rate at rest, during a walk, or during/after an exercise session. This reaction to stress takes place hours/days/weeks before the traditional visual cues that horsemen have relied on for a century. This concept is true for a human, a horse, a donkey, a dog, a rat, etc. – everyone, yet 99.9% of horseman refuse to recognize/utilize this knowledge.

About bpressey

Equine Exercise Physiologist

Posted on October 10, 2011, in Uncategorized. Bookmark the permalink. 2 Comments.

  1. I saw Yeats at Coolmore stud earlier this year. Magnificent tall classical staying physique. Very impressive. Hope they shuttle him to Oz so we can breed some Melbourne Cup winners.
    Having said that I also saw/patted Galileo. I’m tall (6’4″) and next to me he looked like a pony. And he sires Derby winners by the dozen. Go figure.

  2. your site looks good, some interesting stuff on it, keep up the good work.

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