Horse conformation refers to the correctness of a horse's bone structure, musculature, and its body proportions in relation to each other. Undesirable conformation in a horse can limit its ability to perform a specific task. Although there are several universal "faults," a horse's conformation is usually judged by what its intended use may be. Thus "form to function" is one of the first set of trains considered in judging conformation. A horse with poor form for a Grand Prix show jumper could have excellent conformation for a World Champion cutting horse, or to be a champion Draft horse (draft horse showing). It is also important to remember that every horse has good and bad points of its conformation, no horse is perfect, and many horses (including Olympic caliber horses) excel even with conformation faults.
The ideal head varies dramatically from breed to breed, but all breeds are valued for a relatively broad forehead. A broad forehead provides increased sinus capacity, thus there is more room for air exchange through the air passages, and a large surface area for facial muscles that assist in opening the nostrils for air flow. A good head in any breed must also have large eyes, proportionate ears, large nostrils, good width between the jaws, and a smooth joining of the head to the neck. A wide jaw or "throatlatch" allows more than 4 fingers between jaw bones (greater than 7.2 cm wide) A wide throatlatch may make a head appear less flexible, but really it has no effect on the horse accepting the bit and does not restrict air flow. The horse is good for any activity. The ability to breathe deeply is critical to the success of a horse in any endeavor, hence any conformation flaw that restricts breathing capacity is a fault across all breeds.
Some types of heads that distinguish between breed types:
Dished face 
The horse has a concave or "dished" profile, often further emphasized by slight bulging of forehead (jibbah) This structure adds additional sinus capacity, is an adaptation to dry climates, and allows for long periods of aerobic activity, such as Endurance riding. This type of head is seen in light riding horses such as the Arabian horse.
The horse has a convex profile. Properly proportioned, this type of head also has adequate sinus capacity, may be an adaptation to a cold, damp climate, and allows short but sustained bursts of power such as that needed by Draft horses and lighter riding breeds, such as the Baroque horse breeds. It often occurs in some Warmbloods, especially those with a high proportion of draft ancestry.
Faults of the head include:
Pig eye: A small eye, primarily an aesthetic issue, but claimed by some to be linked to stubbornness or nervousness, and thought to decrease the horse's visual field
Opening of the nostrils (the nares) is narrow and somewhat restricted, limiting ability to expand the nostrils for breathing while working hard
May occur in any breed
Especially affects horses in high-speed activities (polo, racing, eventing, steeplechase) or those that need to sustain effort over long duration (endurance, competitive trial, combined driving). These horses are therefore best for pleasure-riding or non-speed sports
Often seen in horses that also have narrow jaws and muzzle
A throatlatch is narrow if it measures less than 7.2 cm (25⁄6 in) diameter. (average for Thoroughbreds)
This is a common fault, seen mostly in Thoroughbreds and Standardbreds, racing and speed horses (racing, steeplechase, eventing, polo)
The horse may suffer from restricted upper airway or air turbulence due to paralysis of recurrent laryngeal nerve (RLN). Horses with this paralysis of one or both cartilages make a roaring sound when working at fast speeds because cartilage collapses into airway space. This causes exercise intolerance, and may lead to stops at a fence due to muscular fatigue. May be associated with “bleeders” (exercise induced pulmonary hemorrhage- EIPH)
A dressage horse or horse to go on the bit in a collected frame may be resistant to do so because flexing at the poll further narrows the airway. However, the horse does not necessarily exhibit a roaring sound. Symptoms include: resistance to bridle, bracing through the poll, neck, and back, difficulty in training to the upper levels.
A horse with a narrow throatlatch is best for work that does not require high speeds
Overshot jaw (parrot mouth) or undershot jaw ("monkey jaw" or "sow mouth")
The upper jaw extends further out than the lower jaw, with the horse having an overbite (parrot mouth), or the lower jaw extends farther out than the upper jaw, with the horse having an underbite (sow mouth).
Both defects can affect the chewing of the horse and the horse's ability to clip grass.
Both defects are fairly rare
The ideal neck is about 1/3 horse’s length, measured from poll to withers, with a length comparable to the length of the legs.
Short Neck 
A neck that is less than 1/3 the length of the horse
Short necks are common, and seen in any breed
A short neck is often quite flexible despite appearing thick and muscular, and the function and range is rarely altered. May be slightly less flexible at the poll, but the horse's maneuverability and agility is generally not affected. It does not shorten stride length, which has more to do with shoulder slope.
The horse may not excel at jumping high obstacles or galloping at high speeds, and may not be as handy at quick directional changes.
Long neck 
A long neck is a neck is one that is much more than 1/3 the length of the horse
Long necks are common, especially in Thoroughbreds, Saddlebreds, and Gaited Horses
It may make it hard to balance the horse, and the horse may fatigue more quickly as a result of carrying too much weight on front end.
Lengthy neck muscles are difficult to develop in size and strength
A long-necked horse needs broad withers to support weight of head and neck
It is easier for the horse to fall into bend of an S-curve than to come through the bridle, which causes horse to fall onto inside shoulder, and makes him difficult for the rider to straighten.
The horse is best for jumping and speed sports (without quick changes of direction), or for straight line riding like trail riding
Excessively large/fallen crest 
The horse has an overly large crest that may fall to one side in extreme cases
Relatively uncommon, although any horse can develop an excessively large crest. It is usually seen in stallions, ponies, Morgans, and draft breeds
It is usually from fat deposits above the nuchal ligament.
An excessively large crest not only looks bad, but it puts more weight on the forehand
Obese horse needs a proper conditioning program
Bull Neck 
The horse has a short, thick, and beefy neck with short upper curve. The attachment to its body is beneath the half-way point down the length of shoulder.
This trait is fairly common, especially in draft breeds, Quarter Horses, and Morgans.
It is generally more difficult to maintain balance if the rider is large and heavy or out of balance, which causes the horse to fall onto forehand. Without a rider, the horse is usually fine.
A bull neck is desirable for draft or carriage horses, so as to provide comfort for the neck collar. The muscles of the neck also generate pulling power.
The horse is best for non-speed sports.
Ewe/ Upside-down Neck 
A neck with internal structure that causes it to bend upward instead of down in the normal arch.
This fault is common and seen in any breed, especially in long-necked horses but mainly in the Arabian Horse and Thoroughbred.
The fault may be caused by a horse who holds his neck high (stargazing). Stargazing makes it difficult for rider to control the horse, who then braces on the bit and is hard-mouthed.
A ewe neck is counter-productive to collection and proper transitions, as the horse only elevates head and doesn’t engage its hind end. The horse's loins and back may become sore.
The sunken crest often fills if horse ridden correctly into bridle. However, the horse's performance will be limited until the proper muscling is developed.
Swan neck  
The horse has a neck set at a high upward angle, with the upper curve arched, yet a dip remains in front of the withers and the muscles bulge on underside.
This conformation type is common, especially in Saddlebreds, Gaited horses, and Thoroughbreds
A swan neck makes it easy for a horse to lean on the bit and curl behind without lifting its back.
The horse is best used for showing, dressage, jumping, and harness work.
Arched/turned-over neck 
The crest is convex or arched with proportional development of all muscles. This is an ideal neck.
Common, seen in all breeds and in all sports.
The neck appears as if it is flowing into the back, so it looks good and creates an efficient lever for maneuvering.
The strength of the neck with proportional development of all muscles improves the swing of shoulder, elevates the shoulder and body, and aids the horse in engaging the hindquarters through activation of the back.
Good for any sport
A long, skinny neck, with poor muscular development on both the top and bottom. Appearance of a straight crest without much substance below.
A knife-neck is relatively uncommon in older horses, although any breed can be affected. It is sometimes seen in young, green horses.
It is usually associated with poor development of back, neck, abdominal and haunch muscles, allowing horse to go in strung-out frame with no collection and on the forehand.
It is often rider-induced, and usually indicates lack of athletic ability.
It can be improved through skillful riding and the careful use of side reins to develop more muscle and stability.
The horse is best for light pleasure riding until its strength is developed
The neck is set on the chest neither too high nor too low, with its weight and balance aligned with the forward movement of the body
Although relatively uncommon, it is usually seen in Thoroughbreds, American Quarter Horses, and some Warmbloods
Advantageous to every sport, as the neck is flexible and works well for balancing
The neck is not too bulky, thin, long, or short. The horse is easy to supple, develop strength, and to control with hand and legs aids.
Conformation of the chest, shoulder, and forearm
Straight, upright, or vertical shoulder
The shoulder blade, measured from the top of the withers to the point of shoulder, lies in an upright position, particularly as it follows the scapular spine. Often accompanies low withers.
Upright shoulders are common, seen in any breed, particularly Quarter Horses. An upright shoulder affects all sports.
The horse has shorter muscular attachments that thus have less ability to contract and lengthen. This shortens the stride length, which requires the horse to take more steps to cover ground, and thus causes a greater risk of injury to structures of front legs and hastened muscular fatigue.
An upright shoulder may cause a rough, inelastic ride due to the high knee action. It increases concussion on front limbs, possibly promoting the development of DJD or navicular disease in hard-working horses. The stress of impact tends to stiffen the muscles of the shoulder, making the horse less supple with a reduced range of motion needed for long stride reach.
An upright shoulder causes the shoulder joint to be open and set low over a short, steep arm bone, making it difficult for horse to elevate its shoulders and fold its angles tightly, which is needed for a good jump and in cutting. Thus the horse usually does not have good form over fences.
The horse is usually easier to accelerate in sprinting.
An upright shoulder is best for gaited or park showing, parade horses, and activities requiring a quick burst of speed, like roping or Quarter Horse racing.
Laid-back or sloping shoulder
The horse has an oblique angle of shoulder (measured from the top of the withers to the point of shoulder) with the withers set well behind the elbow. Often accompanies a deep chest and high withers.
A sloping shoulder is common. It mostly affects jumping, racing, cutting, reining, polo, eventing, and dressage.
The horse has a long shoulder blade to which attached muscles effectively contract and so increase the extension and efficiency of stride. It distributes muscular attachments of the shoulder to the body over a large area, decreasing jar and preventing stiffening of the shoulders with impact. The horse has an elasticity and free swing of its shoulder, enabling extension of stride that is needed in dressage and jumping. A long stride contributes to stamina and assists in maintaining speed.
The longer the bones of the shoulder blade and arm, the easier it is to fold legs in tuck over fences. The laid back scapula slides back to the horizontal as the horse lifts its front legs, increasing the horse's scope over fences. 
A sloping shoulder has better shock-absorption and provides a comfortable ride because it sets the withers back so rider is not over the front legs.
A sloping shoulder is most advantageous for jumping, dressage, eventing, cutting, polo, driving, racing, and endurance.
The Humerus (arm bone)
The arm bone is from the point of shoulder to the elbow, and its length dictates how tightly the elbow and lower joints can bend and reach for extension.
Long arm bone
The humerus is long when it is 50-60% of the length of the scapula. The elbow is beneath the middle of the withers if the humerus is long.
This conformation mostly affects jumping, steeplechase, eventing, lateral movements of dressage, and cutting.
A long humerus increases movement of elbow away from torso, both forward and to the side, allowing more tucking over fences and increased stride in speed events. It provides a scaffold for lengthy muscle attachments of flexor and extensor muscles, which contract with greater force to increase power and speed.
Best suited for speed events, jumping, and dressage.
Short arm bone
Humerus is usually in a horizontal position which closes the shoulder angle (shoulder and humerus) to less than 90 degrees.
Common, usually seen in Quarter Horses, Paints, and Warmbloods
A short humerus decreases the scope of a horse, and contributes to a short, choppy stride. This increases the impact stress on front legs, especially the feet. The rider is jarred and the horse absorbs a lot of concussion. More steps are needed to cover ground, increasing the chance of front-end lameness.
The horse tends to be less able to do lateral movements.
Advantageous for sprinting sports
Horse is best used for pleasure riding, non-impact activities, and sprinting sports like roping or barrel racing
With the horse standing square, the width between the front legs is relatively narrow. However, this can be skewed by how far apart feet are placed at rest. A narrow breast often represents general thickness and development of shoulder.
A narrow breast is usually seen in Gaited horses, Saddlebreds, Paso Finos, and Tennessee Walkers
A horse's ability to carry weight is dependent on the size of its chest, so a horse that doesn't do well with draft work but may be fine in harness or with light rider.
Narrowness may be from turned-in elbows which can cause toes to turn out, aming the horse appear narrow.
Narrowness in the chest may be from immaturity, poor body condition, inadequate nutrition, or under-developed breast muscles from a long time in pasture and lack of consistent work. The horse usually has undeveloped shoulder and neck muscles.
The horse may tend to plait, and is more likely to interfere, especially at the trot
The horse is best for pleasure riding, driving in harness, and trail riding
The front legs come too far back under the body, giving a bulky appearance to the breast as viewed from the side. The front legs lie behind a line drawn from the withers to the ground, setting the horse under himself. It is often associated with a long shoulder blade that drops the point of shoulder somewhat low with the arm bone relatively horizontal, setting the elbow more to the rear.
A relatively uncommon fault, mostly seen in Quarter Horses with big, bulky muscles
Bulky breast muscles and legs set under the body decrease the efficiency of stride and swing of shoulders, thus hastening fatigue. It may interfere with the front legs, forcing them to move to the side rather than directly under horse. Causes a “rolling” gait that slows the horse’s speed, especially at the gallop.
Should have little interfering in the spiriting sports that need rapid acceleration. The inverted V of the pectorals are important for quick turns, doges, and spins needed by stock horses.
This conformation quality is most useful in Quarter Horse racing, barrel racing, roping, and stock horse sports where a low front end crouches & the horse makes quick turns.
The Forearm (radius)
The length of the radius (between elbow and carpus) is long
Seen in all breeds, especially Thoroughbreds, Saddlebreds, Tennessee Walkers, Arabians, and Warmbloods.
A long forearm is desirable for any performance activity, especially if the horse also has a short cannon. It increases the surface area and length of muscular attachments to gain best leverage for maximum stride length and speed.
Good muscling of a long forearm is especially advantageous to jumping horses, as the strong forearm muscles absorb concussion from the impact and diffuse the strain on tendons and joints on landing.
A long forearm is best for speed events, jumping events, and long distance trail riding
The distance of radius from elbow and carpus is proportionately short
Although uncommon, it is usually seen in Morgans and Quarter Horses.
A short forearm affects speed and jumping events, has little effect on stock horse events.
The length of stride is dependent on the forearm length and shoulder angle, so a short forearm causes horse to need to increase the number of steps to cover a distance, increasing overall muscular effort and hastening fatigue.
Increases the action of the knees, giving an animated appearance. Knee action is not compatible with speed.
Best for showing, hunter equitation, harness, parade.
Conformation of the body
The horse has flat and wide withers, from short spines projecting off the 8th-12th vertebrae.
Seen in any breed, most commonly in Ponies, Arabians and American Quarter Horses.
The withers are an important attachment for ligaments and muscles that extend head, neck, shoulder, and back vertebrae, and are also insertion point for muscles that open ribs for breathing. If mutton withered, the horse has less range of motion when extending the head and back muscles, so is less able to elevate its back with its head and neck extended, which affects ability for collection.
Difficult to hold on saddle. If saddle slides forward, it can put weight on the forehand, interfering with balance and restrict the shoulder movement by saddle and rider movement, causing shortened stride, interfering or forging.
The horse is often difficult to fit with a driving harness
Pleasure riding and non-jumping activities are best for the horse
Hollow behind withers
A “shelf” behind the withers, gives a hollow appearance, often created by lack of muscular development
Usually found in high-withered horses of any breed
Often implies a less-developed muscular bed for the saddle to rest on. The saddle will often bridge in this area to pinch the withers, creating soreness of the withers and muscles. The horse is then less willing to move out, extend the shoulders, or use its back, especially for speed or jumping. It also prevents a horse from true elevation of the back needed for collection. A poorly-fitting Saddle (with an insufficiently high pommel arch or a narrow tree) may initiate or exacerbate this condition, as the horse will avoid movements which cause discomfort, thus leading to muscle loss behind the withers.
Horses that trot fast with high, erect neck (like Standardbred race horses) do not develop strong, active back muscles. They are often hollow behind and just below withers due to lack of collection.
This conformation is commonly rider-induced from a horse allowed to move strung-out behind, and is usually seen in gaited horses and long-distance trail or endurance horses.
Protective movement by the horse to minimize saddle pinching may contribute to back pain. Persistent body carriage without collection can overuse some musculoskeletal structure, leading to arthritis.
This conformation will not affect performance if saddle fits correctly. If the saddle does not, the horse is best used for non-speed and non-jumping sports.
High withers 
The 8th through 12th thoracic vertebrae are long and angle backward to create steep, high withers
Especially seen in Thoroughbreds, Saddlebreds, and some Warmbloods
High withers provide a lever for the muscles of the back and neck to work together efficiently. As the head and neck lower to extend, the back and loin muscles correspondingly shorten or lengthen. The backward angle of withers is usually associated with sloping shoulders, which provides good movement of the shoulder blade. This makes it easy for the horse to engage in collection, lengthen, round its back for jumping, or extend its shoulder for improved stride length and speed.
If the withers are too high and narrow, there is a chance that a poorly fit saddle will impinge on withers and slip back too far, creating pain especially with the rider’s weight. Performance and willingness will suffer.
With the back measured from peak of withers to peak of croup, exceeds 1/3 of horse’s overall body length. Usually associated with long, weak loins.
Especially seen in gaited horses, Saddlebreds, Thoroughbreds, and some Warmbloods.
The horse's ability to engage back depends on its ability to elevate the back and loins, requiring strong back and abdominal muscles. A long back is flexible, but harder for horse to stiffen and straighten spine to develop speed or coil loins to collect and engage the hindquarters to thrust rear limbs forward. This then affects upper level dressage, cutting, reining, barrel racing, and polo: sports that require rapid engagement of the hindquarters. Reduced flexion forces the horse to jump flatter with less bascule.
It is difficult to develop a long back's muscle strength, so a horse is more likely to fatigue under the rider and to sway over time. The abdominal have more difficulty in compensating, so they are also less likely to develop. Loins and hindquarters may swing more than normal, increasing the occurrence of sore muscles which leads to a stiff, rigid ride. Cross-firing or speedy cutting likely at high-speeds from a horse with a long back.
Movement of the back is flatter and quieter, making a more comfortable ride and is easier for horse to change leads.
Short back 
The horse's back measures less than 1/3 of overall length of horse from peak of withers to peak of croup
Can be seen in any breed, especially in American Quarter Horses, Arabians, and some Warmbloods
The back may lack flexibility and become stiff and rigid. If vertebral spines of back are excessively small, the horse may have difficulty bending and later develop spinal arthritis. This adversely affects dressage and jumping performance. If still in back and torso, the stride will become stiff and inelastic. The horse may overreach, forge, or scalp itself if the hind legs do not move straight.
The horse may be handy and agile, able to change direction with ease. Good for polo, roping, cutting, reining. If the horse has good muscling, it is able to support weight of rider with rare occurrence of back pain.
Conformation bst used in agility sports
Saddle-, hollow-, low-, sway-backed/ down in the back  
The span of the back dips noticeably in center, forming a concave contour between the withers and croup. Usually causes high head carriage and stiffness through the back. Associated with a long back.
Often associated with weakness of ligaments of the back. Examples include a broodmare who had multiple foals and the back dips with age, an old horse where age is accompanied with weakening of the ligaments, a horse with poor fitness/conditioning that prevents adequate ligament support of the back muscles, or an overuse injury to the muscles and ligaments from excess work, great loads, or premature work on an immature horse.
Some horses with high croups and straight backs often appear to be swayed.
Often accompanies long loins. If the loins aren’t broad, the ligament structures may weaken, causing the back to drop.
A sway back positions the rider behind the center of gravity, interfering with balance. * The horse is unable to elevate for true collection, which can affect any sport but most notably dressage, jumping, and stock work. The back may get sore from lack of support and the rider’s weight.
The horse is unable to achieve rapid impulsion since the rear is less connected with front end. To achieve speed, the horse must create some rigidity in back and spine, which is not possible with a sway. This causes problems in racing, eventing, Steeplechasing, and polo.
This horse is most suited for pleasure riding and for teaching students.
Loins and Coupling
Roached back 
In the area where the back and loins join the croup (the coupling) there is an upward convex curvature of the spine. Often a result of a short back, or injury or malalignment of the lumbar vertebrae.
Often accompanied by less-developed loin muscles in breadth, substance, and strength. The spine already “fixed” in a curved position, and the attaching muscles are unable to contract properly to round or elevate the back. Thus it is difficult to engage the hindquarters or round the back by elevating loin muscles. Vertebrae often have reduced motion so the horse takes shorter steps behind.
Jumping and dressage esp ecially are affected.
The horse is stiffer through the back and less flexible in an up and down motion as well as side to side.
There may be back pain from vertebral impingement.
There is a less elastic feel beneath rider as the back too rigid. Agility sports (polo, cutting, reining, barrel racing, gymkhana) are more difficult.
Long or weak loins/weak coupling 
Coupling is the joining of back at the lumbosacral joint. Ideally, the L-S joint should be directly over the point of hip. Weak coupling is where the L-S joint is further to the rear. The loins are the area formed from last rib to point of hip. Although normally only 2-3 fingers breadth, long loins have more than a hand’s breadth. Long loins are associated with a long back. The croup is often relatively flat and the quarters are high.
Horse with weak or slack loins might have good lateral bend, but collection suffers as true collection depends on coiling loins to bend the hind legs. Because the hind legs and hocks aren’t able to be positioned under body, the hind legs string out behind, so the horse is more likely to go on the forehand. This creates coordination and balance problems, as well as forelimb lameness.
The horse needs the hind legs under for jumping, and for going up and down hill. Weak loins inhibit this, especially affecting eventing, jumping, and trail horses.
The loins regulate the distribution of weight on the forehand by allowing the horse to elevate its back and distribute its weight to the hind end. Horses unable to coil the loins move with stiff backs and a flattened L-S joint, throwing the rear legs out behind. This limits the ability of dressage horses, and also affect reining, cutting, and polo horses as they are unable to explode with thrust.
Rough coupling/widow’s peak
In the loins, the horse has a hollow area considerably lower than foremost part of the croup.
Fairly uncommon, and does not affect the horse's use in sport.
Cosmetically displeasing. Muscling of loins may be ample and strong with minimal effect on ability to collect back or push with haunches. However, if a horse doesn’t have strong loins, it will have difficulty in raising the back for engagement.
Croup and "Hip"
The croup is from the lumbosacral joint to the tail. The "hip" refers to the line running from the ishium of the pelvis (point of the hip) to the point of the buttock. While the two are linked in terms of length and musculature, the angle of the hip and croup do not necessarily correlate. A horse can have a relatively flat croup and a well-angled hip. Racehorses do well with hip angles of 20-30 degrees, trotting horses with 35 degrees.
Steep Croup or Goose rump
A steep croup is often linked to shortened stride
Less of a fault for slow-moving horses such as draft breeds than for light riding horses
Flat or Horizontal Croup
The topline continues in a relatively flat manner to the dock of tail rather than falling off at oblique angle at the hips.
Seen especially in Saddlebreds, Arabians, and Gaited horses
Encourages a long, flowing stride. This helps a horse go faster, especially when a flat croup is sufficiently long to allow a greater range of muscle contraction to move the bony levers of skeleton.
Length from L-S joint to dock of the tail is insufficient for adequate muscular attachment
Reduces power of hindquarters
Usually seen in conjunction with multiple hind leg faults
The L-S joint is often behind the point of hips. Insufficient length from point of hip to point of buttock
Horse will have difficulty collecting.
A well-muscled build may hide a short pelvis.
Provides less length of muscular attachments to the thigh and gaskin. This diminishes engine power in speed or jumping events.
Short hip is less effective as a muscular lever for collection and to contract the abdominal muscles as the back rounds. More muscular effort is required.
Flat pelvis, line from point of hip to point of buttock flat and not properly angled, result is pelvis structure too long. L-S joint often tipped, ishium improperly placed.
It is more difficult to engage the hindquarters, so the back tends to stiffen. Thus it is hard to excel in dressage, jumping, stock horse work. Minimizes the ability to develop power at slower paces needed by draft horses.
Jumper’s Bump (also known as Hunter's or Racking Bump) 
The horse has an enlargement at the top of the croup, or a malalignment of the croup with the pelvis and lumbar vertebrae, caused by the tearing of a ligament at the top of the croup. One or both sides of L-S joint may be affected.
Fairly common, usually seen in jumping horses and in horses that rack in an inverted frame.
It is a torn ligament caused by excessive hindquarter effort, or from a horse that had the hindquarters slip out underneath or trotted up a very steep hill. Usually does not cause problems once healed, although it is easier to re-injure.
Usually associated with horses with weak loins or a long back that is unable to coil loins properly for collection. Commonly caused by overpacing young horses, a rider allowing a horse to jump while strung out, or by racking (or other gaiting) in a very inverted frame.
High Tail Set 
Tail comes out of body on a level with the top of the back.
Commonly seen, usually in Arabians, Saddlebreds, Gaited horses, and Morgans
There is no direct performance consequence. Often, although not always, it is associated with a flat croup. A high-set tail contributes to the appearance of a horizontal croup, which may be an aesthetic concern to some.
Gives as animated appearance, which is good for parade, showing, or driving
Low Tail Set 
Tail comes out of the body well down along the haunches. Associated with goose-rumped or steep pelvis.
Seen in any breed, especially in draft breeds
Only aesthetic concern unless directly caused by pelvic conformation.
Wry Tail/ Tail Carried to One Side
The tail is carried cocked to one side rather than parallel to the spine
May be linked to spinal misalignment, possibly due to injury
May be because the horse is not straight between the rider’s aids, can be used to determine how straight a horse is traveling behind. Over time, incorrect body carriage may place undue stress on limbs.
May be from discomfort, irritation or injury
Ribcage and Flanks
Wide Chest and Barrel/Rib Cage
Rounded ribs increase the dimensions of the chest, creating rounded, cylindrical or barrel shape to the rib cage. Length of the ribs tends to be short.
Seen in any breed, especially American Quarter Horses, and some Warmbloods
Provides ample room for the expansion of the lungs.
Too much roundness increases the size of the barrel, may restrict upper arm movement, the length of stride, and thus speed. Round ribs with a short rib length further restrict the shoulder.
Pushes the rider’s legs further to the side of the body, and can be uncomfortable, especially in sports that require long hours in saddle or that require sensitive leg aids (dressage, cutting, reining).
Pear-Shaped Ribcage/Widens Toward Flank
The horse is narrow at and behind the girth at midchest, then widens toward the flank
Common, especially in Arabians, Saddlebreds, and Gaited horses
Makes it difficult to hold the saddle in place without a breastplate or crupper, especially on uneven terrain, jumping, or low crouch work with quick changes of direction (cutting). When saddle continually shifts, the rider’s balance is affected, and the horse and rider must make constant adjustments. Saddle slippage has the potential to create friction and rubs on back or cause sore back muscles.
Horse is best used in sports on level terrain and for non-jumping activities
Ribs angle backward with sufficient length, breadth, and spacing with arched rib cage and deep chest from front to back. Largest part of the barrel is just behind the girth area. Last rib is sprung outward and inclined to the rear, with the other ribs similar in length, roundness, and rearward direction.
Desirable for any sport.
Promotes strong air intake, improving performance and muscular efficiency
Ample area of attachment of shoulder, leg and neck muscles, enabling a large range of motion for muscular contraction and speed of stride.
The rider’s weight is easily balanced and stabilized since the saddle stays steady and the rider can maintain close contact on horse’s side with leg.
There is sufficient room for developing strong loin muscles while still having short loin distance between last rib and point of hip (close coupling).
Poor spring of the ribs due to flatness and vertical alignment of the ribs. Ribs are adequate in length.
Common, especially in Thoroughbreds, Saddlebreds, Tennessee Walkers, and Gaited horses
There is less room for the lungs to expand, limiting the efficiency of muscular metabolism with prolonged, arduous exercise
If there is a short depth in the chest, the horse will have a limited lung capacity which is likely to limit the horse's ability for speed work
Horse generally has lateral flexibility.
Narrowness makes it difficult for the rider to apply aids since the legs often hangs down without fully closing on the horse. More effort needed to stay on horse’s back because of limited leg contact and the saddle tends to shift.
Horse has a harder time carrying the rider’s weight because of reduced base of support by narrow back muscles.
Waist beneath the flanks is angular, narrow, and tucked up with a limited development of abdominal muscles. Often associated with short rear ribs, or undernourished horses.
Seen in any breed
Often a result of how horse is trained and ridden. If a horse doesn’t use its back to engage, they never develop their abdominal muscles. Appears to be like a lean runner (greyhoundish), with stringy muscles on topline and gaskin.
Lack of abdominal development reduces overall strength of movement. Stamina is reduced, and the back is predisposed to injury. The horse is incapable of fluid, elastic stride, but is probably capable of ground-cover despite correct body carriage.
Speed and jumping sports should be avoided until the muscles are developed.
Good Depth of Back
The depth of the back is the vertical distance from lowest point of back to bottom of abdomen. Point in front of sheath or udder should be parallel to the ground and comparable in depth to front portion of chest just behind the elbow at the girth.
Seen in any breed, especially Warmbloods, Quarter Horses, and Morgans.
Good depth indicates strong abdominal muscles, which are important for strength and speed. Critical to dressage, jumping, and racing. Strong abdominals go with a strong back, which is suitable for carrying a rider’s weight and engaging the haunches.
Should not be confused with an obese horse in “show” condition, as fat just conceals wasp-waistedness.
Conformation of the Hindquarters and Hips
Measured from the point of hip to the point of buttock, the hindquarters should be ideally at least 30% of length of overall horse. Anything less is considered short. Most horses are between 29-33%; Thoroughbreds may have a length reaching 35%.
Insufficient length minimizes the length of the muscles needed for powerful and rapid muscular contraction. Thus, its reduces speed over distance, stamina, sprint power, and staying ability.
Tends to reduce the horse's ability to fully engage the hindquarters need for collection or to break in a sliding stop
Horse is most suited for pleasure sports that don’t require speed or power
Viewed form the side, the pelvis assumes a steep, downward slope.
Uncommon, except in draft horses, but seen in some Warmbloods.
A steep slant of the pelvis lowers the point of buttock bringing it closer to the ground & shortening the length of muscles from the point of buttock & the gaskin. Shortens the backward swing of the leg because of reduced extension & rotation of hip joint. A horse needs a good range of hip to get a good galloping speed and mechanical efficiency of hip and croup for power & thrust. Therefore, a goose-rumped horse is not good at flat racing or sprinting.
Harder for a horse to “get under” and engage the hindquarters. Causes the loins and lower back to work harder, predisposing them to injury.
A goose-rump is valuable in sports with rapid turns & spins (reining, cutting). The horse is able to generate power for short, slow steps (good for draft work).
Horse is most suited for stock horse work, slow power events (draft in harness), low speed events (equitation, pleasure, trail)
Viewed from the side, the pelvis has a relatively flat, but sloping profile of adequate length, but the flatness does not extend to the dock of the tail as in a Flat-Crouped horse.
Common in some Warmbloods and may be considered a desirable trait in some breeds.
This conformation allows good engagement of the hindquarters, while giving the long stride and speed of Flat-Crouped conformation.
Often associated with good jumping performance.
Note that the term Goose-Rumped is sometimes used as a synonym for Steep-Rumped, potentially causing confusion, as the two conformations imply rather different qualities in the horse's performance.
The horse has poor development in the hindquarters, especially the quadriceps and thighs. Associated with goosed-rumps & sickle hocks.
Uncommon, most usually seen in Gaited horses. Can develop from years in confinement. B
The horse lacks the development needed for speed and power, so the horse is not fast or strong. Thus it is not adventageous for flat racing, polo, eventing, jumping, steeplechase, and harness racing.
The horse's gait tends to be more ambling than driving at the trot, so the horse often develops a stiff torso & back, making the ride rigid.
Viewed from the rear, the breadth between the hips is narrow.
Common, seen in any breed, although Quarter Horses tend not to have them. Usually in Thoroughbreds, Saddlebreds, Arabians, and Gaited horses.
A narrow pelvis contributes to speed since the horse can get its hind legs well under its body to develop thrust.
The narrow hip shape is partially dictated by exercise development of haunch muscles.
Good width widens the breadth between stifles, hocks & lower legs to enable power, acceleration, & foot purchase into ground, preventing interference injuries. Narrow pelvis limits size of muscular attachments of hips, affecting strength & power.
The horse is best suited for flat racing, trail, carriage driving
Wide, flat hip shaped like a "T" when viewed from behind. Cattle tend to have this pelvis type to the extreme.
Uncommon, usually seen in Gaited horses, Saddlebreds, and Arabs.
Rafter hips are often amplified by poor muscling along thighs and lower hips. Exercises to improve muscling helps the problem.
One Hip Bone Lower/Knocked-Down Hip
From behind, the point of hip on one side is lower than the other. May be due to an injury to the point of hip, or to sublaxtion or fracture of the pelvis.
Generally induced by a traumatic blow to hip. Not heritable.
The gait symmetry is affected (which is bad for dressage or show horse). Interference with power and thrust may alter strength of jumping high fences or reduce speed.
The horse is more prone to developing muscular or ligament soreness associated with re-injury or strain. This is especially likely to occur in a jumper, racer, steeplechaser, or eventer. However, in most cases the horse recovers completely.
High Stifles/ Short Hip
Ideal hip forms equilateral triangle from point of buttock, point of hip, and stifle. A short hip has a short femur (thigh bone) that reduces the length of quadriceps and thigh muscles. The femur is short when the stifle seems high (sits above sheath in male horse)
Found in any breed, but usually in racing Quarter Horses or Thoroughbreds.
Effective in generating short, rapid, powerful strokes (sprint or draft work). The horse has a rapid thrust & thus rapid initiation of sprint speed.
Ideally, the bones of the gaskin and femur should be of similar length in horse that does anything but sprint or draft work. A short femur reduces stride length behind & elasticity of stride that jumpers, dressage horses, and flat/harness racers want.
Low Stifle/ Long Hip
A long hip is created by a long femur which drops the level of stifle to or below the sheath line on a male horse.
Favorable in all sports except sprint sports and draft work
Enables the horse to develop speed and power after it gets moving.
The muscles of the hip, haunches, and thighs will be proportionately long with a long hipbone, giving the horse the capacity to develop speed and power over a sizable distance. Produces ground-covering and efficient stride in all gaits.
Good for eventing, steeplechase/timber, flat/harness racing, jumping, and long distance riding
Conformation of the Front and Hind Legs
The Cannon & Tendons
Long Cannon Bone 
The cannon is long between the knee and fetlock, making the knees appear high relative to the overall balance of the horse
Reduces the muscular pull of the tendons on the lower leg.
Uneven terrain or unlevel foot balance will magnify the stress on the carpus since lengthy tendons are not as stabilizing to the lower limb as shorter ones
Increases the weight on the end of the limb, contributing to less efficient and less stable movement. Added weight to front legs increases the muscular effort needed in picking up a limb, leading to hastened fatigue.
Increase in tendon/ligament injury, especially when the horse is also tied-in above the knee.
Horses with long cannons are best for flat racing short distances.
Short Cannon Bone
Cannon is relatively short from fetlock to knee as compared to knee to elbow
This conformation is desirable in any performance horse
A short cannon bone improves the ease and power of the force generated by the muscles of a long forearm or gaskin. Enables an efficient pull of the tendons across the back of the knee or point of hock to move the limb forward and back.
Also reduces the weight of the lower leg so less muscular effort is needed to move the limb, which contributes to speed, stamina, soundness, and jumping ability.
Rotated Cannon Bone 
The cannon rotates to the outside of the knee so it appears twisted in its axis relative to knee. May still be correct & straight in alignment of joint, but more often associated with appearance of carpus valgus.
Places excess strain on the inside of the knee and lower joints of the leg, potentially leading to soundness issues, although this is not common.
Bench or Offset Knees/ Offset Cannons
The cannons are set to the outside of the knee so an imaginary plumb line does not fall through middle.
Causes excessive strain on the lateral surfaces of the joints from the knee down and on the outside portions of the hoof.
There is an exaggerated amount of weight supported by the medial splint bone, leading to splints.
The horse is most suited for non-speed activities like pleasure riding, driving, and equitation.
Tied-in Below the Knee
The cannon, just below the knee, appears “cut out” with a decreased tendon diameter. Rather than parallel with cannon, tendons are narrower than the circumference measured just above the fetlock.
Limits the strength of the flexor tendons that are needed to absorb the concussion and diffusion of impact through the legs, making the horse more prone to tendon injuries, especially at the midpoint of the cannon or just above.
The leverage of muscle pull is decreased as the tendons pull against the back of knee rather than a straight line down back of leg. This reduces power and speed.
Associated with a reduced size in the accessory carpal bone on back of knee over which the tendons pass. The small joints are prone to injury and don’t provide adequate support for the column of leg while under weight-bearing stress.
Horse is most suited for sports that shift the animal's weight to the rear or that don’t depend on perfect forelimb conformation (dressage, driving, cutting).
One or both knees deviate inward toward each other, with the lower leg angles out, resulting in a toed-out stance. Occurs because of an unequal development of the growth plate of distal radius, with the outside growth plate growing faster than inside. The bottom of the forearm seems to incline inward.
Any horse can inherit this, but it may also be acquired from imbalanced nutrition leading to developmental orthopedic disease (DOD) or a traumatic injury to growth plate.
The horse is most suited for pleasure riding, low-impact, and low speed events * The medial supporting ligaments of the carpus will be under excess tension. May cause soundness problems in the carpals or supporting ligaments. Horse also tends to toe-out, causing those related problems.
Bucked, Sprung, or Goat Knees/ Over at the Knee 
Knee inclines forward, in front of a plumb line, when viewed from the side.
Often a result of an injury to the check ligament or to the structures at the back of the knee. The column of the leg is weakened. Thus, the horse is apt to stumble and lose balance due to the reduced flexibility and from the knee joints that always are “sprung.”
If congenital, often associated with poor muscle development on the front of the forearms, which limits speed and power.
More stress is applied to the tendons, increasing the risk of bowed tendons. The angle of attachment of the DDF and check ligament is increased, predisposing the check ligament to strain. Tendons and fetlock are in an increased tension at all times, so the horse is predisposed to injury to the suspensory (desmitis) and sesamoid bones. If the pasterns are more upright there is further stress.
Calf-Kneed/Back at the Knee 
The knee inclines backward, behind a straight plumb line dropped from the middle of the forearm to the fetlock.
Usually leads to unsoundness in horses in speed sports. Places excess stress on the knee joint as it overextends at high speeds when loaded with weight. Backward angle causes compression fractures to the front surfaces of the carpals, and may cause ligament injury within knee. Worsens with muscle fatigue as the supporting muscles & ligaments loose their stabilizing function.
Calf-knees weaken the mechanical efficiency of the forearm muscles as they pull across the back of the carpus, so a horse has less power and speed. The tendons and check ligament assume an excess load so the horse is at risk for strain. Often the carpals are small & can’t diffuse the concussion of impact. ∑
The horse should have good shoeing, eliminating LTLH (long-toe, low-heel) syndrome.
Sports that have more hindquarter function, like dressage, or slow moving activities like pleasure riding, are best for this horse.
The Front Legs- The Fetlock
Toed-Out/Lateral Deviation of Pastern from Fetlock/ Fetlock Valgus 
An angular limb deformity that creates a toed-out appearance from the fetlock down.
A fairly common fault
Creates excess strain on one side of the hoof, pastern and fetlock, predisposing the horse to DJD, ringbone, foot soreness or bruising.
The horse will tend to wing, possibly causing an interference injury. May damage splint or cannon bone.
This conformation diminishes the push from rear legs, as symmetry and timing of the striding is altered with the rotated foot placement, particularity at the trot. Thus, stride efficiency is affected to slow the horse’s gait.
The horse is unable to sustain years of hard work.
Toed-In/Medial Deviation of Pastern/Fetlock Varus
An angular limb deformity causing a pigeon toed appearance from the fetlock down, with the toe pointing in toward the opposite limb.
Horse is most suited for pleasure riding, non-impact, low-speed, and non-pivoting work.
These horses tend to paddle, creating excess motion and twisting of the joints with the hoof in the air. This is unappealing in show horse, wasteful energy, which reduces the efficiency of the stride, so the horse fatigues more quickly. The hoof initially impacts ground on inside wall, causing excess stress on the inside structures of the limb, leading to ringbone (DJD) & sole or heel bruising in inside of hoof.
Short Gaskin/Hocks High
Results from a relatively short tibia with a long cannon. Ideally, hocks are slightly higher than the knees, with the point of hock level with the chestnut of the front leg. Hocks will be noticeable higher in horse with this conformation. * The horse may have a downhill balance with the croup higher than the withers.
See especially in Thoroughbreds, racing Quarter Horses, and Gaited horses.
With this conformation, the horse can pull the hind legs further under the body, so there is a longer hind end stride, but the animal may not move in synchrony with the front. This will create an inefficient gait, as the hind end is forced to slow down to let the front end catch up, or the horse may take high steps behind, giving a flashy, stiff hock and stifle look. May cause forging or overreaching. ∑
Often results in sickle hock conformation.
Long Gaskin/Low Hocks
Long tibia with short cannons. Creates an appearance of squatting.
Usually seen in Thoroughbreds and stock horses.
A long gaskin causes the hocks and lower legs to go behind the body in a camped-out position. The leg must sickle to get it under the body to develop thrust, causing those related problems.
The long lever arm reduces muscle efficiency to drive the limb forward. This makes it hard to engage the hindquarters. The rear limbs may not track up & the horse may have a reduced rear stride length, forcing the horse to take short steps.
The horse is best used for galloping events, sprinting sports with rapid takeoff for short distance, or draft events.
Hocks Too Small
Hock appears small relative to the breadth and size of adjacent bones. Same principals with knees too small.
The joints are a fulcrum which tendons and muscles pass over for power & speed, and large joints absorb concussion & diffuse the load of the horse. Small joints are prone to DJD from concussion & instability, especially in events where the horse works off its hocks a lot.
A small hock doesn’t have a long tuber calcis (point of hock) over which the tendons pass to make a fulcrum. This limits the mechanical advantage to propel the horse at speed. The breadth of the gaskin also depends on hock size, and will be smaller.
Cut Out Under the Hock
Front of the cannon, where it joins the hock, seems small & weak compared to the hock joint. In the front end, its called “tied in at knee.”
Mainly affects sports that depend on strong hocks (dressage, stock horse, jumping)
Reduces the diameter of the hock and cannon, which weakens the strength & stability of the hocks. Means a hock is less able to support a twisting motion (pirouettes, roll backs, sudden stops, sudden turns). The horse is at greater risk for arthritis or injury in hock.
Camped Out Behind 
Cannon and fetlock are “behind” the plumb line dropped from point of buttock. Associated with upright rear pasterns.
Seen especially in Gaited horses, Morgans, and Thoroughbreds.
Rear leg moves with greater swing before the hoof contacts the ground, which wastes energy, reduces stride efficiency, & increases osculation & vibrations felt in joints, tendons, ligaments, & hoof. May cause quarter cracks & arthritis.
Difficult to bring the hocks & cannons under unless the horse makes a sickle hocked configuration. Thus, the trot is inhibited by long, overangulation of the legs & the horse trots with a flat stride with the legs strung out behind.
It is difficult to engage the back or haunches, so it is hard to do upper level dressage movements, bascule over jumps, or gallop efficiently.
Sickle- or Sabre-Hocked/ Overangulated Long Hind Legs 
The hind leg slants forward, in front of the plumb line, when viewed from the side. The cannon is unable to be put in vertical position. Also called “curby” hock, as it is associated with strain of plantar ligament on the rear, lower part of the hock.
Limits the straightening & backward extension of hocks, which this limits push-off, propulsion, & speed. There is overall more hock & stifle stress.
Closed angulation & loading on the back of the hock predisposes the horse to bone & bog spavin, thoroughpin, & curb.
Angles of the hock & stifle are open. The tibia is fairly vertical, rather than having a more normal 60 degree slope
Common, usually seen in Thoroughbreds, steeplechasers, timber horses, eventers, and hunter/jumpers.
In theory, sickle hocks facilitate forward & rearward reach as the hock opens & closes with a full ranger of motion without the hock bones impinging on one another. This lead to selective breeding of speed horses with straight rear legs, especially long gaskins.
The problem is that this breeding has been taken to the extreme. Tension on the hock irritates the joint capsule & cartilage, leading to bog & bone spavin. Restriction of the Achilles tendon sheath while in motion leads to thoroughpin. A straight stifle limits the ligaments across the patella, predisposing the horse to upward fixation of the patella, with the stifle in a locked position, which interferes with performance & can lead to arthritis of stifle.
It is difficult for the horse to use its lower back, reducing the power & swing of the leg.
Rapid thrust of the rear limbs causes the feet to stab into the ground, leading to bruises & quarter cracks.
Hocks deviate from each other to fall outside of plumb line, dropped from point of buttocks, when the horse is viewed from behind.
Most commonly seen in Quarter Horses with a bulldog stance.
Hoof swings in as the horse picks up its hocks & then rotates out, predisposing the animal to interference & causing excess stress on lateral hock structures, predisposing the horse to bog & bone spavin, & thoroughpin.
The twisting motion of the hocks causes a screwing motion on the hoof as it hits the ground, leading to bruises, corns, quarter cracks, and ringbone.
The horse does not reach forward as well with the hind legs because of the twisting motion of the hocks once lifted, & the legs may not clear the abdomen if the stifles are directed more forward than normal. This reduces efficiency for speed & power.
Cow Hocks/Medial Deviation of the Hocks/Tarsus Valgus
Hocks deviate toward each other, with the cannon & fetlock to the outside of the hocks when the horse is viewed from the side. Gives the appearance of a half-moon contour from the stifle to hoof. Often accompanied by sickle hocks.
Fairly common, usually seen in draft breeds.
Disadvantages to trotting horses, harness racers, jumpers, speed events, and stock horses. ∑
Many times Arabians, Trakehners, & horses of Arabian descent are thought to have cow hocks. But really the fetlocks are in alignment beneath the hocks, so they’re not true cow hocks.
A slight inward turning of hocks is not considered a defect & should have no effect.
A horse with a very round barrel will be force to turn stifles more out, giving a cow-hocked appearance
Medial deviation in true cow hocks causes strain on the inside of the hock joint, predisposing the horse to bone spavin. Abnormal twisting of pastern & cannon predisposes fetlocks to injury.
More weight is carried on medial part of hoof, so it is more likely to cause bruising, quarter cracks, & corns. The lower legs twist beneath the hocks, causing interfering.
The horse develops relatively weak thrust, so speed usually suffers.
Conformation of the Pasterns
The angle of the pasterns is best at a moderate slope (about 50 degrees) and moderate length.
Pasterns Long and Sloping 
The pastern are long (more than 3/4 length of cannon) relative to rest of leg.
This defect affects long-distance and speed sports
Long pasterns have been favored because can diffuse impact, giving a more comfortable ride. However, excess length puts extreme tension on the tendons and ligaments of the back of the leg, predisposing the horse to a bowed tendon or suspensory ligament injury. The suspensory is strained because fetlock is unable to straighten as horse loads the limb with weight.
The pasterns are weak and unable to stabilize fetlock drop, so the horse is predisposed to ankle injuries, espescially in speed events where the sesamoids are under extreme pressure from the pull of the suspensory. This can cause sesamoid fractures & breakdown injuries.
May be associated with high or low ringbone. Increased drop of fetlock causes more stress on pastern and coffin joints, setting up conditions for arthritis.
There is a delay time to get the feet off the ground to accelerate, and thus long pasterns make the horse poor for speed events.
The horse is best for pleasuring riding, equitation, and dressage
Pasterns Short and Upright 
A horse's pasterns are short if they are less than 1/2 length of cannon. The pasterns are upright if they are angled more toward the vertical. A long, upright pastern has the same performance consequences as short and upright.
Most commonly seen in Quarter Horses, Paints, and Warmbloods
The horse is capable of rapid acceleration, but is restricted to a short stride. They excel in sprint sports. The short stride is a result of both a short pastern and upright shoulder, creating a short, choppy stride with minimal elasticity and limited speed.
Short pasterns have less shock-absorption, leading to more a jarring ride and amplified stress on the lower leg. The concussion is felt over the navicular apparatus, so the horse is more at risk for navicular disease, high or low ringbone, and sidebone. Also windpuffs and windgalls occur from chronic irritation within fetlock or flexor tendon sheath.
The horse has reduced mechanical efficiency for lifting and breaking over the toe, so it may trip or stumble.
The horse is best for sprint sports like Quarter Horse racing, barrel racing, roping, reining, and cutting
Conformation of the Feet and Base
The horse's feet are turned away from each other
Causes winging motion that may lead to interfering injury around fetlock or splint.
As horse wings inward, there is a chance that he may step on himself, stumble, and fall.
A horse that is “tied in behind the elbow” has restricted movement of the upper arm because there is less clearance for the humerus (it angles into the body too much). Reduced clearance of legs causes horse to toe-out to compensate.
Toes of hooves face in toward each other
Pigeon-toes cause excess strain on the outside of the lower structures of the limb as the horse hits hard on the outside hoof wall. This often leads to high or low ringbone. The horse is also predisposed to sidebone and sole bruising.
The horse moves with a paddling motion, wasting energy and hastening fatigue so that he has less stamina.
Base Narrow in Front: Toed-Out or Toed-In
The feet are closer together and more under the body than the shoulders
Fairly common fault
Base-narrow, toed-out: Stresses the outside structures of the limb, especially the outside of the foot. Causes a winging motion, leading to interfering. Predisposes the horse to plaiting. The horse tends to hit himself more when fatigued.
Base narrow, toed-in: Excessive strain on the lateral structures of fetlock, pastern, and outside of hoof wall. Causes the horse to paddle.
The horse is least suited for speed or agility sports.
Base Wide in Front: Toed-In or Toed-Out
The horse stands with its feet placed wider at the shoulders, often associated with a narrow chest.
Base wide, toed-out: the horse lands hard on the outside of the hoof wall and places excessive strain on the medial structures of the fetlock and pastern, leading to ringbone or sidebone, & potentially spraining structures of the carpus. The horse will wing in, possibly leading to an interference injury or overload injury of the splint bone.
Base wide, toed-in: the horse lands hard on the inside hoof wall, placing stress on the medial structures of limb. The horse will also paddle.
Stands Close Behind/Base Narrow Behind
With a plumb line from the point of buttock, the lower legs & feet are placed more toward the midline than the regions of hips & thigh, with a plumb line falling to the outside of the lower leg from the hock downward. Usually accompanied by bow-legged conformation.
A fairly common fault, especially in heavily muscled horses like Quarter Horses.
The hooves tend to wing in, so the horse is more likely to interfere. If the hocks touch, they may also interfere.
The horse can’t develop speed for rapid acceleration.
The outside of the hocks, fetlocks, & hooves receive excessive stress & pressure. This leads to DJD, ligament strain, hoof bruising, & quarter cracks.
The horse is best for non-speed sports & those that don’t require spins, dodges, or tight turns
Feet Too Small  
Relative to size and body mass, the feet are proportionately small
There is a propensity to breed for small feet in Thoroughbreds, Saddlebreds, and American Quarter Horses.
A small foot is less capable of diffusing impact stress with each footfall than a larger one.
On hard footing, the foot itself receives extra concussion. Over time, this can lead to sole bruising, laminitis, heel soreness, navicular disease, and ringbone. Sore-footed horses take short, choppy strides, so they have a rough ride and no gait efficiency.
If the horse has good shoeing support, it can comfortably participate in any sport, although it is more likely to stay sound in sports that involve soft footing.
Feet Large and Flat/ Mushroom-Footed 
Large in width & breadth relative to body size & mass. May have slight pastern bones relative to large coffin bone.
Flat feet limit the soundness of the horse in concussion sports (jumping, eventing, steeplechase, distance riding).
Without proper shoeing or support, the sole may flatten. Low, flat soles are predisposed to laminitis or bruising. The horse takes on a choppy, short stride. It is hard for the horse to walk on rocky or rugged footing without extra protection on the hoof.
A large foot with good cup to sole is ideal foot for any horse. There is less incidence of lameness, and it is associated with good bone.
For flat footed horses, sports with soft footing and short distances like dressage, equitation, flat racing, barrel racing are best.
Horse has a narrow, oval foot with steep walls
Mule feet are fairly common, usually seen in American Quarter Horses, Arabians, Saddlebreds, Tennessee Walkers, Foxtrotters, and Mules
A mule foot provides little shock absorption to foot & limb, creating issues like sole bruising, corns, laminitis, navicular, sidebone, and ringbone. Not all horses have soundness issues, especially if they are light on the front end & have very tough horn.
Because the hind end provides propulsion, it is normal to see more narrower hooves on back compared to front
Soft-terrain sports like polo, dressage, arena work (equitation, reining, cutting), and pleasure riding are most suitable
The slope of hoof wall is steeper than the pastern, often associated with long, sloping pasterns tending to the horizontal, which breaks the angulation between pastern and hoof. Usually seen in rear feet, esp in post-legged horses. Coon feet are sometimes due to a weak suspensory that allows the fetlock to drop.
Quite uncommon, it particularly affects speed sports and agility sports
Coon feet create similar problems as too long & sloping pasterns (the horse prone to run-down injuries on back of fetlock). If foot lift off is delayed in bad footing, ligament and tendon strain & injury to the sesamoid bones is likely.
Weakness to supporting ligaments due to post leg or injury to suspensory will result in a coon-foot as the fetlock drops.
The horse is most suited for low-speed exercise like pleasure riding or equitation
Club Foot  
The slope of the front face of hoof exceeds 60 degrees. Horse often has long, upright heels. May be from contracture of DDF (deep digital flexor tendon) that was not addressed at birth or developed from nutritional imbalances or trauma.
Fairly common, best to use horse in activities done in soft-footing & those that depend on strong hindquarter usage
Various degrees of angulation, from slight to very pronounced. Horses with obvious club feet land more on the toes, causing toe bruising or laminitis. The horse generally does poorly at prolonged exercise, especially if on hard or uneven terrain (eventing, trail riding).
Because the toe is easily bruised, the horse moves with a short, choppy stride, and may stumble. The horse is a poor jumping prospect due to trauma incurred on impact of landing.
Contracted Heels 
The heels appear narrow and the sulci of frogs are deep while frog may be atrophied
May be seen in any breed, but most common in American Quarter Horses, Thoroughbreds, Saddlebreds, Tennessee Walkers, or Gaited horses
Contracted heels are not normally inherited, but a symptom of limb unsoundness. A horse in pain will protect the limb by landing more softly on it. Over time, the structures contract. The source of pain should be explored by a vet.
Contracted heels create problems like thrush. The horse losses shock absorption ability, creating navicular, sole bruising, laminitis, and corns. May restrict heel expansibility, causing lameness from pressure around coffin bone & reduced elasticity of digital cushion.
Horse is best used for non-concussion sports.
Wall is narrow and thin when viewed from bottom. Often associated with flat feet or too small feet.
Common, especially in American Quarter Horses, Thoroughbreds, and Saddlebreds.
Thin walls reduce the weight-bearing base of support, and are often accompanied by flat or tender soles that easily bruise. The horse is subject to developing corns at the angles of the bar. The horse tends to grow long-toes with low heels, moving the hoof tubules in horizontal direction, and so it reduces shock absorption ability and increases the risk of lameness.
Less integrity for expansion and flexion of hoof, making it more brittle and prone to sand & quarter cracks. Narrow white line makes it hard to hold shoes on.
Horse does best when worked only on soft footing.
Flared Hoof Wall 
One side of the hoof flares towards its bottom, relative to the steep appearance of the other side. Flared surface is concave.
Horse is best to use in low-impact or low-speed sports
May be conformationally induced from angular limb deformity or malalignments of the bones within the hoof. These conformational problems cause excess strain on one side of hoof making it steepen, while the side with less impact grows to a flare. The coronary band often slopes asymmetrically due to pushing of hoof wall & coronet on steep side, which gets more impact than flared. May develop sheared heels, causing lameness issues, contracted heels & thrush.
May be acquired from imbalanced trimming methods over time that stimulate more stress on one side of foot.
Chronic lameness may make the horse load the limb unevenly, even if the lameness may be in hock or stifle.
The Horse's Overall Balance and Bone
Measuring the circumference of the top of the cannon bone, just below the knee, gives an estimation of the substance. Ideally a 1,000 lb horse should have 7-8 inches. Insufficient is less than 7 inches for every 1,000 lb of weight.
A horse with insufficient bone is more at risk for injury (within the bones, joints, muscle, tendons, ligaments, and feet).
Repeated impact creates soundness issues, especially in those sports with a lot of concussion (jumping, galloping, racing, long distance trail). Track horses get bucked shins, event and trail horses get strained tendons and ligaments.
Light-Framed/Fine Boned 
Substance of long bones is slight and thin relative to the size & mass of the horse. Especially noticed in the area of the cannon & pastern.
Seen especially in show horses, halter horses in non-performance work, Paso Finos, Gaited horses, and Thoroughbreds.
Affects the longevity of performance horses.
See “insufficient bone.” Doesn’t provide ample support for bulky musculature & there is a lack of harmony visually.
Theoretically, a lighter frame reduces the weight on the end of the limbs, making it easier to pick up the legs & move freely across the ground. However, with a lot of speed & impact work, light bone suffers concussion injury, leading to bucked shins, splints, & stress fractures. Tendons, ligaments, & muscles have less lever system to pull across to effectively use or develop muscle strength for power & stamina.
It is best to match the horse with a petite & lean rider. It is best to use the horse for pleasure, trail, driving, non-impact sports, and non-speed work.
Long bones are big, wide, & strong in a horse with either light or bulky muscled appearance.
Seen especially in Quarter Horses, Arabians, draft horses, ponies, Morgans, and Warmbloods.
Advantageous for any sport, the horse tends to hold up well.
THe horses tend to be rugged and durable, capable of carrying large weights relative to size.
Big, solid bones provide strong levers for the muscles to pull against to improve efficiency of motion, thus minimizing the effort of exercise & reduces the likelihood of fatigue, contributing to endurance. May add mass to each leg, and consequently slightly hinder speed at the gallop when flat racing.
The horse is best used in distance trail, jumping, eventing, steeplechase, timber, reining, cutting, polo, roping, barrel racing, driving, and harness racing.
Withers Higher than Croup 
The peak of the withers is higher than the peak of the croup when the horse is square.
This is what is referred to as built uphill. It is very advantageous in dressage, eventing, etc as the horse has an easier time engaging the hind end.
Common in well-built warmbloods.
Withers Lower than Croup/Rump High/Downhill Balance 
The peak of the croup is higher than the peak of the withers. This is less desirable than a horse with higher withers.
Seen in any breed but especially in Thoroughbreds and Quarter Horses.
Young horses are usually built this way.
More weight is placed on the forehand, reducing the front-end agility. Muscles must work harder to lift the forehand, leading to muscular fatigue. It is difficult to raise the forehand at the base of a jump for liftoff. At speed, more work of loins, back & front end is needed to lift the forelimbs.
Increases concussion on the front legs, so the horse is at greater risk of front-end lameness. Greater jar on the rider.
Tends to throw the saddle & rider toward the shoulders, leading to chaffing, pressure around withers, & restricted shoulder movement.
Too Tall (in context to rider) 
Horse is tall compared to the size of the rider.
Usually seen with Thoroughbreds, Warmbloods, and draft horses.
The ability to communicate with the seat & leg is affected. The rider looks awkward.
A tall horse is not as handy or agile.
Too Short (in context to rider) 
When compared to the rider, the horse is disproportionately short.
Usually seen with Arabians, Barbs, Paso Finos, Morgans, small QHs, and ponies.
Can interfere with athletic ability of horse by:
The horse may not be able to maintain balance (top heavy), so it may be more prone to tripping or falling if the rider loses a balanced seat position.
Heaviness of the rider in proportion to horse’s mass can cause a sore back and loins & rapid muscle fatigue in general, reducing stamina.
The horse may be unwilling to jump or run fast because of extreme work to carry large rider on back, which forces a horse to overuse the muscles while the front limbs receive excess strain and impact with a risk of developing lameness problems.
It is difficult for a rider to find point of balance, as the rider's legs barely touch a horse’s narrow sides. Thus it is hard for rider to use leg aids.
Horse is best used for pleasure, non-speed work, non-jumping sports, & sports that don’t require quick changes of direction/speed.
Horse should carry less than 25% of body weight (rider & tack) as a general rule of thumb. Horses with short backs and more dense, compact bone structure may be able to carry more weight.