Supplement Article To: The Up And Down Of It – Shoulder Angle And Slope

Paint Mare wrote in the comments section:

After I read this post, I looked up the recent Equus articles on shoulders. The article on seeing a shoulder said that while usually you can measure the angle of the shoulder by tracing a line from the point of the shoulder to the middle of the withers, some horses have a shoulder blade that runs in front of that ideal line, further up the neck. The article said this isn’t the best conformation, though didn’t seem to really specify why. When I look at the Paint Mare, I think she is in fact built this way. And as she is the primary horse I get to examine and prod, that’s made me a bit confused over how to see the shoulder! Whether you follow the ideal line or the actual line changes how steep the angle of her shoulder is, and how open the arm joint.

I’m attaching a photobucket album that shows her in current fit mode, but also as a green broke 5 year old with less muscle. Any thoughts? We have always found her a bit restricted in the shoulder though she has some relatively snappy high knee action at the trot, and can lift her knees OK jumping if she gets the right distance.

Paint Mare sent me some photos of her – Paint mare – so let’s examine more closely.

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I don’t see her scapula being ahead in position.  It’s not ‘middle of withers’, it’s ‘highest point of withers’.  That latter gives the impression of being forward with the rest of the withers tapering off gradually as you want to see.  When measured, her slope is about 52/53 degrees with a closed shoulder angle of 85ish degrees.  Her humerus has great length being about 67%, and is a bit more toward vertical than horizontal.

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This is one of those contradictory type mixes of conformation, but in the end the humerus bone wins.  It’s not vertical enough in orientation and thus the creation of a closed shoulder angle rules the outcome: reduced range of motion causing an inability to get the knees up well for jumping (forearm below perpendicular to the ground) and be tight below.

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Paint mare included a second picture.  Note that to get the knee up on the right front her horse had to badly twist the shoulder and leg.  The left front leg shows a much tighter lower leg, but to achieve that the horse had to lower its knee and also twist the shoulder and leg.

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Additionally, some of the issue is from a muddy shoulder bed and tightness behind the wither and into the back.  This can be improved with stretching, massage and more engagement so that the horse lifts its base of neck, withers and back.

Paint Mare will know this has been achieved when the dip in front of the withers disappears, the lower neck thins, she can place her whole hand under the scapula along its entire length, the hollow behind the withers fills in and the horse develops a double back along its entire length.

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Looking at other aspects of this horse’s conformation, I see no reason it can’t be achieved rather easily and in a relatively short period of time – 4-6 months – and when done the horse’s jumping form will have improved.  There’s a lot to like about this horse, despite that closed shoulder angle.

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The Up And Down Of It – Shoulder Angle/Humerus Bone – Part 2

In part one I talked about the difference between shoulder slope and shoulder angle.  The important parts to remember are;

  • We want the horse’s shoulder slope to largely land between 45-55 degrees, the lower end for a Dressage horse and the upper end for a jumper, outside that range at either end is doable but comes with potential issues
  •  Anything less than 90 degrees is a closed shoulder angle and significantly affects potential stride length, and for most horses it should be a deal breaker
  •  A horse standing with its front legs too far under its body or too far out in front of its body will artificially change the shoulder angle

The above addresses the swing potential of the front leg, but there’s something else in the front end that determines all the rest, specifically the style of the horse’s movement; daisy cutter or high knee action and everything in between.  Even the horse’s front end lateral movement comes from this: the length and orientation to the horizon of the humerus bone.   The humerus is attached to the scapula at the point of shoulder by a ball and socket joint giving the humerus bone forward and back motion as well as side to side motion.  At the other end the humerus joins the radius-ulna (forearm) bone creating the elbow joint.

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Here are the basic rules about the humerus bone:

  • The longer the humerus bone the more scope to the horse’s movement, forward and back as well as laterally – a long humerus bone must be at least 50% the length of the scapula
  • The shorter the humerus bone the more choppy the horse’s movement – a short humerus bone would be less than 50% the length of the scapula
  • The steeper (vertical) the humerus bone the higher the horse can lift its knees (think knees to ears in the jumping horse)
  • The more horizontal the humerus bone the less natural ability the horse has to lift its knees to create high action or fold it’s knee (think daisy cutter and a horse that hangs its knees over jumps)

(Note: The humerus bone along with the shoulder angle determines a short, choppy stride, not a short or upright pastern as is so often claimed.)

Gaited horses that are prized for their high knee action would thusly possess a long humerus bone orientated more vertically and likely also possess a quite open shoulder angle, well exceeding 90 degrees.  This would be the same for a Jumper that could put his knees to his ears with the exception of the placement of his knees being lower by having a shorter cannon bone; a requirement to stay sound from repeated landing concussion.

The Dressage horse will also possess a long humerus bone, but less vertical compared to the gaited or jumping horse and in most cases not as open a shoulder angle, but certainly still maintaining the minimum 90 degrees.  The shoulder slope of the Dressage horse will tend to be more laid back than the jumper.

The Hunter horse with a long, sweeping, and low daisy cutting action will also have a long humerus bone, but it will lie more horizontal limiting the ability of the knee to be raised.

The stilted front end gait of many Western horses is due to a closed shoulder angle and/or a shorter humerus bone set horizontally.

Horse #1 – QH Stallion

 ZansParityQHStalEquineNowAd

Our QH stallion has very good length to his humerus bone at approximately 64%.  This trait helps to minimize the effects of his slightly closed shoulder angle.  The humerus more on a horizontal orientation giving flat movement.

 ZansParityQHStalEquineNowAd-ShoulderMarked

Horse #2 – QH Gelding

QHGEquineNowAd

This QH gelding also has very good length to his humerus bone at about the same 64%.  Its orientation is identical to our stallion, except that we know this horse is not standing with his front legs properly underneath himself.  If he was, then his humerus would be a bit more vertical than our first horse.  However, paired with a slightly more laid back shoulder (and the same closed shoulder angle) these two horses should move in the same general manner with their front legs.

 QHGEquineNowAd-ShoulderMarked

Horse #3 – 4yr old QH

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This horse has the longest humerus bone of the group at 67%.  He also has the most vertical orientation of the lot and with the most open shoulder angle.  Coupled with his upright shoulder and surprisingly this horse has the potential to bring his knees up the most and fold his lower leg the tightest of this group, as well to have very good scope and potential for lateral movement.   Though he should have more expression to his gait than the first two QH’s, I’d bet my own money (again) that he moves in a typical QH fashion, flat and short.  I’ll talk about why in a future article.

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Horse #4 – Arabian Stallion

 BaskeAflameArabDreamHorseAd

Another long humerus bone at 60%, with a vertical orientation between that of the QH stallion and the grey QH, paired with an all-around shoulder slope of 50 degrees and adequate shoulder angle gives this horse middle of the road action (neither daisy cutter nor hackney) and scope.

 BaskeAflameArabDreamHorseAd-ShoulderMarked

Horse #5 – TB Gelding

 IvanOFTBDreamHorseAd

We’ve won the lottery as here is another horse that still maintains a long humerus at 59%.  The orientation is identical to our Arabian, but with the more upright shoulder we should expect our TB to be able to lift the knee a bit higher, but the lower leg no tighter due to shoulder angle and humerus bones length being very much alike.  Both horses should possess similar scope and lateral potential.

 IvanOFTBDreamHorseAd-ShoulderMarked

Horse #6 – Paint Mare

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Our Paint mare has the shortest humerus of the group at approximately 55.5%, which still makes it long enough but she will have the least scope and lateral movement of all of our horses.  Unfortunately it’s also the most horizontally placed on a quite upright shoulder.  Still she manages to keep a minimum 90 degree shoulder angle.

While it’s a desirable trait to have a long shoulder, this horse has too much shoulder length placing the point of shoulder too low.  This low placement puts a horse more over its shoulder and onto its front end.  Horses of this construction tend to be forever pigeon-breasted.  She’s a contradiction.  The upright shoulder says she can bring the knee up, but the horizontal humerus says she can’t.  The humerus bone wins every time and so a horse constructed like this will lead with its chest when it jumps and hang its knees all day long, every day.

PaintMareDHad-ShoulderMarked

The Up And Down Of It – Shoulder Slope And Angle – Part 1

Shoulder slope and shoulder angle are two entirely different things when discussing equine conformation, yet many times the terms are used incorrectly or interchangeably. Shoulder slope references the slope at which the scapula sits in direct relation to the horizon, while shoulder angle is the angle created at the joining of the scapula and humerus bones.

Shoulder slope:  is marked from highest point of wither to point of shoulder and then measured against the horizon. The slope of the horse’s shoulder ranges between 40-60 degrees. A slope of 45 degrees is considered ‘laid back’ and is ideal for Dressage horses. A slope of 55 degrees is considered ‘straight or upright’ and is more useful in jumping or gaited horses for lifting the knee.  A shoulder slope of 50 degrees is what I call ‘utility or all-around’.

At the outer limits of range we have 40 and 60. A horse possessing a shoulder excessively laid back is still quite functional and not necessarily prone to lameness, but a horse designed like this will give their owner a headache when it comes to saddle fit. The scapula will lay back so much that it’s next to impossible for a saddle to be done up when it’s sitting in the correct position on the horse’s back. Placing it so it can be done up with the girth not around the horse’s belly puts it over the scapula.  As we know, a saddle in this position would block the ability of the scapula to move freely thusly also blocking movement of the horse’s entire front leg. Even a cutback saddle won’t always fit this conformation. The only horses I’ve ever seen carry this kind of conformation are some Friesians and some Drafts.  Note that for carriage or Draft horses, that a laid back shoulder is desired to more readily fit a collar.

 At the other end of the range, the very upright 60 degree shoulder also does not create unsoundness, in and of itself. Nor does it create a short, choppy stride as is often thought, though, a feeling of less elasticity can certainly be an outcome. What it does do is create added concussive stress through the entire forelimb, which in turn can cause unsoundness. Neither ends of the spectrum are desirable in a horse and should be avoided on principle alone, that principle being what’s best for horses and allowing them to perform their jobs without undue risk to longevity.

Shoulder angle:  is marked by adding a second line to the shoulder slope line from point of shoulder to point of elbow.  The subsequent angle created between the two lines is then measured. The angle created at the joint can range from 80-115 degrees. 90 degrees is the magic number here; anything less and the horse will be short-strided in the forelimb. No other combination of traits can make up for that short-stridedness, or nullify an angle below 90 degrees. In many cases it should be a deal breaker. Anything over and above 90 degrees is a bonus. Many of the GP jumpers who are able to bring their knees to their ears possess an angle at the higher limit of the range.

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Let’s look at our random sampling of horses and see how they measure up.

Horse #1 – QH Stallion

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Our stallion carries a typical lovely shoulder slope of 50 degrees.  It’s the kind of trait that fits a versatile breed.  Not surprisingly, though, he also carries a shoulder angle of less than 90 degrees – about 85.  This latter is unfortunately a trait that is quite prevalent in the QH breed.

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Horse #2 – QH Gelding

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This horse’s shoulder slope is approximately 48 degrees, unfortunately he too has a closed shoulder angle and more so than our first horse.  It measures about 78 degrees.  However, this is not really his actually shoulder angle, which is closer to the same 85 as our first horse.  Note that this horse stands with his shoulder angle artificially closed by standing ‘over’ his point of shoulder with his forelimbs too far under his body – leaning forward.  If he stood how he should, his shoulder angle would open a bit, but still be less than 90 degrees.

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Horse #3 – 4yr old QH

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Here we have our first upright shoulder at 55 degrees.  What surprised me was that it’s combined with an open 95 degree shoulder angle.  This combination is unusual in QH’s, more often seen in TB’s.   I wonder if this guy isn’t expressing some TB influence in his pedigree.

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Horse #4 – Arabian Stallion

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Another lovely all-around shoulder slope of 50 degrees, but to my surprise his shoulder angle is also closed at 85 degrees.  This is highly unusual for an Arabian, such that I actually went back a few times to recheck the points and numbers.  The lighting in the photo, which perfectly highlights his bones, confirms the results.   If we account for the right front leg being, perhaps, a bit too far underneath then we can add a degree or two, but it still puts the angle short of adequate.  But then I had to consider the clubbed foot, which with its too high heel is going to artificially close the shoulder angle by lifting the elbow (note it also slightly buckles the horse’s knee putting him over at the knee on that leg).  I would bet some of my own money that if we had a photo from this horse’s other side, that the shoulder angle would measure the desired 90 degrees.

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Horse #5 – TB Gelding

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As expected, our TB has a more upright shoulder at approximately 54 degrees.  The angle is ever so slightly closed at 89 degrees, but note the left front leg is a bit too far underneath the body and so our TB actually possesses an adequate shoulder angle of 90 degrees (and possibly even a touch more).

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Horse #6 – Paint Mare

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Our paint mare has the most upright shoulder of the lot at approximately 57 degrees and an adequate angle of 90 degrees.

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In part two I’ll discuss the signficant importance of the humerus bone and its direct relation to the scapula.