The Trapezoid Theory

There are several great tools you can use to train your eye to see a horse’s overall balance and structure. One that has been around the block with many trainers and breeders is the “trapezoid” theory.

The Journal asked three Quarter Horse industry professionals to help explain it: AQHA Professional Horsewoman June Warren of Yukon, Oklahoma; Carol McWhirter of Doniphan, Nebraska; and Philip “Vic” Clark of Shelby, Ohio. They collaborated in a lecture on the topic at the 2005 All American Quarter Horse Congress. Unfortunately, June died in 2010, but her wisdom – as well as Carol’s and Vic’s – is worth passing on.

“The trapezoid tells me if a horse is truly balanced,” June said. “A balanced individual is more likely to have good movement, athletic ability and soundness.”

When you first look for a horse’s trapezoid, try drawing it out on a good conformation photo taken in profile on level ground or use a string to mark it out on a horse.

Draw It Out

1. Level Ground
   Have the horse stand balanced on level ground. The weight should be evenly distributed over the front and hind legs, not leaning forward or back. At least one front leg and one hind leg should be square under the body.
2. Back Line
   Imagine a line parallel with the ground, extending along the horse’s back from the middle of the withers to the middle of the loin.
3. Body Line
   Imagine another line parallel with the ground, extending from the horse’s chest at the point of the shoulder to the rear just below the buttocks.
4. Angles
   Complete a symmetrical trapezoid (isosceles trapezoid) over the horse’s body. Connect the back line at the withers to the body line at the point of the shoulder. Connect the back line at the loin to the body line at the rear, just below the point of the buttocks.

What It Tells You

As June, Carol and Vic evaluate a horse, they keep the perfect trapezoid in mind as a guide.

“To ‘see’ the trapezoid in a horse’s structure, I visually ‘strip’ the horse, first the skin, then muscle, and picture the horse’s skeleton in front of me,” June explained. “This allows me to look through an overweight or underweight horse, or one that is not properly conditioned. It also keeps me from being fooled by a fit, pretty horse that might not be structurally correct.

“The true test is not how many inches a certain body part is, but how the parts relate to each other,” she added.

First, if the line along the back is level with the ground, you can see if the horse is built “uphill” (withers higher than the croup), “level” (withers level with the croup) or “downhill” (withers lower than the croup).

“I’ve heard it said that an untrained horse in nature carries 60 percent of its weight on the front end,” Carol said. “As a horse is trained, it learns to assume more weight on its hindquarters through muscular development. If you watch high-level dressage horses or advanced reiners, they shift their weight to their hindquarters when they work.”

That’s easier to do naturally for a horse that is built level or uphill.

In addition, in a balanced horse, the back should be one-third the length of the horse’s body, or very close to it. That creates a short topline and a long underline.

The opposite (not parallel) sides of the trapezoid should be the same in length. They follow the slope of the shoulder and pelvis, and the slopes of those bones always correspond in a horse.

The figure helps you evaluate the slope of the shoulder and hip. The angle formed between the line along the shoulder and the body line should be the same as the angle formed by the line along the pelvis and body line. Ideally, they’re close to 45 degrees – the wider those angles are, the straighter the shoulder and the steeper the croup.

“(The trapezoid) tells me if the horse has a hip equal to his shoulder in both size and slope, and if the length of his back is correct in relation to his body,” June said. “Those all contribute to the horse having a stronger topline, making it easier for him to carry himself properly.

“A horse with a good slope to his shoulder will have a better reach with his front leg and will have more correct head carriage,” she continued. “A shorter back will make it easier for the horse to round his back and engage his hindquarter to create drive.

“The correct slope to the croup and hip will make it easier for the horse to keep his hind end underneath him and use his hocks and stifles correctly.”

Idea in Action

Balance is the most important factor all three horsemen use in selecting stock for any reason.

“A horse’s structure will dictate his movement, and the more balanced he is, the better his potential for good movement and athletic ability,” June said. “It is the best tool I know of to improve the odds of turning out good show horses whether you are trying to breed, or find or train them. You can only possibly hope to make them the best that their structure will allow.”

Vic pointed out that there are great horses that don’t meet these criteria for balance and that mental attitude plays a big role in their performance.

“But those horses that defy form-to-function conformation and are still fabulous performers are the exception rather than the rule,” he said. “If you walk through any top breeders’ barn, their horses will fit this (trapezoid) mold.”

A horse’s pedigree doesn’t mean anything if a horse doesn’t have the conformation to go with it,” he said. “What the pedigree means is if the horse has the conformation and has a good pedigree, then the pedigree increases the odds dramatically that what you are looking at will reproduce itself.”

June would rather compromise other things, not balance.

“I will pick a horse that is not as pretty but is balanced over one that is pretty but lacks an area of balance,” June said. “A horse’s head does not determine his movement.

“If I compromise anywhere on balance, it would be with a slightly longer back,” she added. “I have found that if the other elements are there, the horse has great hocks and is strong over the back and loin, the back can be a little longer, and he can still be a good under-saddle horse.

“But if the shoulder and croup are too steep and the hocks are weak, it will not matter how short the back is because the horse will never have a big, strong stride.”

Breeding for Balance

“Horses are erector sets,” Carol said, “When you are breeding horses, it goes right back to the skeleton; you are breeding length of bone to length of bone.

“If you throw away all the muscle and coat color, all the frosting on top of the cake, a horse can only move the way its bare bones erector set says it can move,” she continued. “If you have wrong angles, you aren’t going to fix it, no matter how famous its parents or how good a trainer you have. You’ve got to start with the right erector set.”