Leg Confirmation
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This article is based on how to judge leg confirmation and
the suitability for the horses life i.e jumping, trailing,
dressage etc.
Leg
Conformation
Good leg conformation in a horse is a must if that animal is to
remain serviceably sound for a lifetime of work and
performance. No matter how beautiful or well-pedigreed a horse,
it will matter little if the animal suffers from chronic
lameness. No legs, no horse.
Often when discussing good leg conformation, we use the term
"straight legs." If that term is taken at face value for all
parts of the leg, it is totally inappropriate. For certain
parts of the leg, we should, instead, be discussing correct
angle.
Oldtimers loved to use the term "flat bone" when talking about
good leg conformation. Technically, there is no such thing as a
"flat" bone in a horse’s leg. The bones are round, or
oval-shaped. What these horsemen are referring to is a lower
leg with solid, round bones backed by appropriately sized
tendons and ligaments. When viewed from the side, such a
healthy leg will give the appearance of being flat.
You should view the forelimbs from the front and the side while
the horse is standing on a solid, level surface.
Proper leg conformation for the equine is highly important in
all of its endeavors. This is especially true of horses in the
wild, where nature is a ruthless culling agent. The wild horse
whose legs give out because of poor conformation might wind up
being an evening meal for a predator. While wild horses in
general might not look like show ring models, it is seldom that
one will find wild horses with serious leg conformation
problems. Most wild horses with poor leg conformation don’t
make it to adulthood.
The domestic horse doesn’t face that type of brutal culling.
Expensive therapeutic shoes and procedures might be involved in
straightening out a foal’s crooked legs. In a friendly
environment, helped by modern science, it has a much better
chance of growing up and becoming a useful horse than would its
wild counterpart with the same problem.
This is always a good news/bad news scenario. The good news is
that the horse can be turned into a serviceable animal which
will survive its malady and provide its owner with many
enjoyable outings. The bad news is that if this horse becomes
part of a breeding program, the problem, if heritable, will be
passed on to another generation, sometimes without the
knowledge of the people breeding to the horse.
Even when we breed a horse with good leg conformation to
another which has good legs, we are not guaranteed that the
foal will have proper conformation. However, the odds are much
more on our side than they are when one of the parents has
poorly conformed legs.
Horses must be able to move forward if they are to be useful to
man. For some trail horses, all that might be asked is to move
forward at a walk over gentle terrain. Others, however, might
be asked to move forward while climbing a rocky trail that
leads to the top of a mountain. For still others, moving
forward means cantering across an arena and sailing over
obstacles on a jumping course. There are those which are asked
to run at speed around an oval track with money, honor, and
glory awaiting the winner. Still others will race in a
cloverleaf pattern around barrels, putting tremendous torque on
bones, tendons, and muscles as they scramble through the
tightest of turns.
Whatever the use to which it is put, the horse will not remain
sound and serviceable for performance after performance or ride
after ride if it doesn’t have properly conformed legs.
Even horses which have properly conformed legs often can wind
up being lame as the result of over-exertion or injury. When
the leg is poorly conformed, the problems are compounded.
We should always bear in mind that there are many things about
a horse we can change, but some things we cannot. If a horse is
thin, we can provide extra nourishment so that it gains weight.
If it is out of shape, we can launch an exercise program for it
that will strengthen muscles and tendons. If it has bad teeth,
we can help correct the problem by calling in a dental
specialist.
If, however, the horse was born with improper leg conformation,
there really is nothing we can do about it by the time the
horse is an adult. Corrective shoeing might help somewhat, and
corrective devices can be effective in straightening crooked
legs in a foal, but that is about it. Despite taking these
steps, nothing will have changed the fact that the horse was
born with improper leg conformation and continued soundness is
at risk.
There are, of course, exceptions to every rule. Some horses
perform well with conformation faults. I remember a
three-gaited National Show Horse which won national
championships even though he had a serious conformational fault
in one leg. I have mentioned in the past that one of my very
best trail horses traveled up and down mountains for years and
never took a lame step, even though one of his front legs was
cocked at an angle. There also have been racehorses which have
beaten the odds and won stakes money despite being born with
poor leg conformation.
However, for every exception to the rule there will be a
thousand others with similar problems which were unable to
perform. If one is in the market for a horse, it is far better
to start with good leg conformation rather than hope you might
have bought an exception.
Front End
Conformation
When talking leg conformation, the discussion normally starts
with the front end. There is a valid reason for that. The front
limbs support as much as 65% of the horse’s weight when at
rest. That’s just when the horse is standing still. When it is
running at speed or jumping, strong concussive forces are added
to the weight bearing. At one point in every stride when a
horse is galloping, all of the weight comes to bear on the
leading foreleg. Near the end of a race, when fatigue is
becoming a factor, the poorly conformed foreleg is in jeopardy
every stride.
We are indebted to Professor Byron Good of Michigan State
University for the phrase "form to function" when discussing
proper conformation. Professor Good was not saying that every
horse should be constructed alike. Far from it. The best "form
to function"is vastly different if you are looking for a
racehorse which can run a mile as compared to a cutting horse
which only makes short spurts, sliding stops, and quick
turn-arounds in a relatively small pen. The legs of the cutting
horse will be shorter and stouter than its counterpart which is
asked to run a mile or more at speed.
Thus, there should be differences in leg types for horses which
are used for various events. But no matter what the use,
correct leg conformation remains the same, whether we are
discussing a 17-hand, long-legged racehorse or a 15-hand stout,
short-legged cutting horse.
The bones of a horse’s front legs are not connected to its
skeleton. The entire front leg, from scapula on down, could
be
amputated without the scalpel ever touching bone. The horse’s
front legs are connected to its skeleton by a network of
muscles, ligaments, and tendons. In a manner of speaking, the
front legs support a sling that supports the forward part of
the horse’s body.
When we take a look at the horse’s front legs to determine
whether they have good conformation, we will use the
aforementioned terms "straight" and "angle." When looking at
the horse’s front legs from a head-on position, we want to see
a straight leg. When viewing it from the side, we want to see
proper angle at certain points, such as the fetlock.
If all of the bones, tendons, and ligaments, as we view the
horse from the side existed in a perfectly straight line from
bottom to top, the horse’s leg would be unable to serve its
function of shock absorber. The perfectly straight leg would
send direct concussion from ground level up and into the
horse’s body without impediment during each step.
When foot, fetlock, and shoulder are properly angled, however,
much of the concussion is dissipated along the way.
Before we get any further into the discussion on proper angle,
let’s take a look at the rest of the bone structure from
shoulder to foot. The horse’s shoulder bone or scapula is a
broad bone that connects to the next bone in line-the humerus.
The humerus angles down and rearward and joins the radius or
forearm at the elbow. The radius, in turn, extends downward to
the knee or carpus. Connecting to the bottom part of the carpus
is the metacarpus or cannon bone, which runs down and into the
pastern. The long pastern bone is known as the first phalanx or
P1. It fits into the second phalanx or P2, also known as the
short pastern bone. The second phalanx fits into the third
phalanx or P3, more commonly known as the coffin bone.
Just behind the cannon bone, where it joins the long pastern
bone, are the sesamoid bones, which serve as pulleys for the
superficial and deep flexor tendons. Another bone of the foot
that is heavily involved with the suspensory ligaments is the
distal sesamoid bone, located at the junction of the short
pastern bone and the coffin bone. Its common name is the
navicular bone.
There are two other bones in each of the front legs. They are
located on either side of the cannon bone and are known as the
splint bones. They support the bones of the knee and help to
dissipate energy transmitted to the metacarpal region. If
identical, there will be a precise and smooth articulation of
the long pastern bone with the short pastern bone and of the
short pastern bone with the coffin bone. The general belief is
that they are evolutionary remnants from the prehistoric
three-toed horse. Although they serve little practical purpose
today, they can, nevertheless, be involved in lameness
problems.
Let's start with the side view of the front leg, seeking to
establish just what are appropriate angles.
Angles
A horse with good conformation will have a front shoulder that
is laid back or angled at an appropriate degree. Just exactly
what the degree is will vary from horse to horse. Having the
proper angle is key to the horse’s stride. If the shoulder is
steep and straight, the horse’s stride will be short and
choppy, which translates into discomfort for the rider. The
horse’s front feet will hit the ground more often over a given
distance, with the concussion from each stride traveling all
the way up the leg and into the body.
When looking at the horse from the side, check the angle formed
by the ground under the hoof and the slope of the pastern. As
is the case with the shoulder, this angle will vary from horse
to horse.
Often a horse will have about the same degree of angle to its
pastern as it does in its shoulder. Many old timers used to
claim that horses with the best conformation had front pasterns
at a 45-degree angle to the ground. That theory is no longer
considered valid. There is no universal degree for all horses.
Today, 45 degrees would be considered the minimum acceptable
angle in front for most horses.
One thing is a must if a horse is to have properly conformed
front legs-the slope of the pastern must be identical to the
slope of the foot. If identical, there will be a precise and
smooth insertion of the long pastern bone into the short
pastern bone and of the short pastern bone into the coffin
bone. If these bones do not mesh correctly, strain is placed on
tendons and ligaments and lameness often results.
So what should we be seeing when viewing a properly conformed
leg from the side? When a horse is viewed in profile, one with
good conformation will appear to have a straight, vertical
alignment from the middle of its forearm all the way to the
ground just behind its heel. The angles should be at the
shoulder and pastern. The rest of the leg should be
straight.
Now let’s step in front of the horse. Here, again, we can use
the term "straight leg." When looking at the horse from the
front, superimpose a mental vertical line. It should travel in
a straight path from the point of the shoulder, through the
middle of the forearm and down the cannon bone, pastern, and
foot. No angles there. Just a straight line. Any deviations are
aspects of poor leg conformation.
We also want to see the same distance between the forearms at
the chest as between the two feet on the ground. If the
distance is narrower at the feet, the horse is said to be
base-narrow. If the reverse is true, the horse is said to be
base-wide.
One of the most serious front leg conformational defects is
called toeing out. When looking at the horse with our straight
vertical line imposed, we will observe that the toes are turned
outward and the line, instead of traversing the center of the
foot, will be to the inside.
A horse with this fault is gong to put extra stress on the
inside of its knee with every stride. There is another problem
when dealing with this fault. As the horse travels,
particularly at the trot, it will wing in. This poses a
constant danger to the horse of striking the sesamoids, the
splint bones, or the coronet band of its opposite foreleg.
The reverse problem occurs in a horse which toes in or is
pigeon-toed. In that case, our line will be to the outside of
the foot, rather than straight down the middle. Such a horse
will have a tendency to wing out or paddle when it moves, but
at least it isn’t in danger of striking itself.
A fault that is in the same category for severity as the toed
out horse is one that is referred to as being bench-kneed. This
means that the forearm and cannon bone do not line up. Instead,
the forearm will enter the knee on the inside or medial aspect
while the cannon bone will exit more on the outside or lateral
aspect of the knee (or vice versa). Such a horse is likely to
develop knee trouble when asked to perform in a stressful
discipline. Another is back-at-the-knee. When viewed from the
side, the knee takes on a dished appearance. When placed under
stress, especially if the tendons and ligaments are fatigued
such as at the end of a race, the knee will overextend backward
and can cause permanent injury.
The knee is something of a precarious structure at best and
needs all the help it can get to avoid injury. When looking at
an illustration or model of the knee bones, I always am
reminded of children’s building blocks that are balanced in
rows, one on top of the other. With that illustration in mind,
it might become easier to understand why deviations from normal
conformation, such as bench knees, can create serious soundness
problems. Unless one bone blends smoothly into another at the
joints, the effects of weight and concussion are not properly
handled.
The key to checking front leg conformation is to observe the
horse in motion as well as at rest. Corrective shoeing or
trimming might diminish the appearance of some conformational
defects, but man-made solutions to poor conformation cannot
change the bone structure that caused the problem in the first
place. The problem horse whose hooves have been modified to
cover up a toeing-in or toeing-out problem might look straight
and correct when standing, but the problem will surface at the
trot, sometimes in dramatic fashion.
When we have a horse with poor leg conformation, such as my
aforementioned trail horse, the only chance we have of keeping
it sound is to trim or shoe the foot to the direction or angle
that nature dictated instead of seeking to change it. With that
approach, the defect will remain, but at least the horse has
the advantage of the existing muscles, tendons, and ligaments
being aligned in a way that provides the most strength and
durability for its natural conformation.
Hind
Limbs
We started with the front because that is where the most weight
is borne. However, proper rear leg conformation is as important
as proper front limb conformation if a horse is to remain
sound. A horse which is unable to propel itself forward at the
pace desired because of poorly constructed rear legs will not
be suitable for riding or driving.
As with the front legs, good rear limb conformation is a must,
no matter what the discipline. Trail horses traveling across
mountainous terrain need strong, durable rear legs that can
propel them up steep slopes and slow the rate of descent when
coming back down. Jumpers need strong, sound rear legs to
launch their bodies into the air. A cutting horse or reining
horse has continuous need of strong, rear limbs for power,
turning, and stopping. The same is true of upper level dressage
horses. The list goes on.
As we did with the front legs, we will take a look at all of
the bones involved in a horse’s rear limbs. We start at the
spine where the ilium, the largest of three bones in the
pelvis, connects with the spinal column. The angular shape of a
the horse’s pelvis determines whether it has a flat croup or a
sloped croup.
The ilium angles down and back to blend into the femur or thigh
bone. The femur angles slightly forward to the stifle.
Beginning at the stifle is the tibia, which continues down to
the hock. From the hock to the pastern is the metatarsus or
rear cannon bone, which flows downward into the long pastern
bone, short pastern bone, and coffin bone.
The two areas most at risk of lameness in the rear legs are the
hocks and the stifles. The stifle is the joint at which the
femur ends and the tibia begins. Relating it to human anatomy,
the stifle serves the same function as a human’s knee.
The hocks play a key role because tendons pass over them to
transmit energy from the muscles to provide propulsion. Unless
the hock is properly conformed, each step produces undue
stress.
How do we determine if a horse has good rear limb conformation?
We’ll start by stepping directly behind the horse for an
assessment. First of all, we want to see the same distance
between the hocks as we see between the feet on the ground.
When observing from behind, the horse’s rear legs should be
straight. If a vertical line were drawn on a photo taken from
behind, the line would go as straight as a plumb line from the
center of the buttocks downward through the center of the
entire rear leg, including pastern and foot.
Now, let’s step to the side and take a look. When you look at
the rear legs from this view, keep the term angulation in mind.
The angle of the stifle and the hock should not be too straight
or too angular, but should present a well-balanced picture with
muscles running smoothly down the leg to the hock.
Using an imaginary plumb line again, we should be able to start
it at the rear of the buttocks and drop a straight line
downward to the hock and then along the cannon bone until it
reaches the ground three to four inches behind the heel.
Any deviations indicate poor rear leg conformation that can
range from one of the worst, being wide at the hocks, to one
not quite so severe, being too narrow or cow-hocked.
So, go out and take a good look at your horse from the front
and the side. Learn what is normal for him, and discuss his
conformation with your veterinarian and farrier to learn what
you should expect from him based on the sport or discipline in
which you participate.
Good leg conformation is no guarantee that a horse will never
take a lame step, but the chances are much more in our favor
than they are with the horse that has poor limb
conformation.
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