Horse conformation and soundness

To survive in nature a horse needs to be able to eat, drink and outrun predators. To survive as a species, he needs to be able to reproduce. A sound horse is one capable of performing all of these functions to a maximum genetic potential. Lameness is an obvious unsoundness often caused by poor conformation, but horses can be unsound in other areas as well, for example, in health, reproductive capabilities, temperament. Soundness can be relative to purpose – a calf-kneed horse might break down under the pressure of fast work like racing but remain perfectly sound for normal riding.

Conformation and soundness are intimately linked. Conformation is the overall shape of a horse and is variable between breeds in details such as average height and weight, overall build, refinement of head, etc, but to remain sound, all breeds must have the same basic correct conformation. A well-conformed horse of any breed has a look of balance and squareness, and an imaginary plumb line should equally bisect any limb all the way to the ground. The neck, body and hindquarter must all be in proportion.

There is a popular expression “no hoof no horse”, but it is the leg to which the hoof is attached that can be even more important. Too few horse enthusiasts truly recognise poor limb conformation. Too many show awards are given to bad-legged horses, and there are plenty of photos in horse magazines to illustrate this. It is for this reason that many people distrust or devalue led-in show awards, because poor leg conformation can lead to unsoundness, lameness or breakdown. One should be beware too of expressions like “good-boned” or “game-headed” or “stands over a lot of ground”, they are airy-fairy rubbish often used by showring judges. A horse may indeed have someone’s interpretation of a “game head”, but failure to recognise that this same horse may have limb conformation faults with the potential to cause unsoundness is a serious contravention of welfare.

Inherited unsoundnesses

Rig (cryptorchid). A horse with only one visible testicle, the other being up inside the abdomen or inguinal canal. Rigs cannot be gelded in the normal way and should not be bred from as the condition is inherited. Rigs that are partially gelded retain the characteristics and behaviour of stallions but are infertile, unless the retained testicle has almost descended. Most colt foals are born with two testicles present, but if not, up to 18 months should be allowed before declaring the colt a rig.

Parrot mouth. Also called an overshot jaw, because the upper incisors overlap the lower ones - in severe cases by up to 8 cms (3 inches). The molars are not always involved. Many foals are slightly parrot mouthed but grow out of it, and there are orthodontic treatments available that are claimed to help rectify the condition. Horses can also be undershot, but this is much rarer.

If severe enough the affliction is obvious without having to open the mouth, as it is quite unsightly. Such horses have a hard time grazing efficiently, although they do still manage presumably by using their tongue and hard palate more, provided the grass is of reasonable length. Should a parrot-mouthed horse be bred from? This is the real dilemma because the defect does not affect performance. Also the genetics is not straight forward, a parrot-mouthed horse might throw the condition only rarely, and two parrot-mouthed horses do not necessarily produce an affected foal.

Umbilical hernia. An umbilical hernia is a swelling in the region of the umbilicus (navel) in an otherwise healthy foal. It results from failure of the abdominal wall in this area to close properly after birth. The resulting defect allows the internal lining of the abdomen to bulge through. If the hernia is large it may contain a piece of intestine which can become twisted or occluded resulting in severe colic and a medical emergency.

The condition is not uncommon, particularly in Thoroughbred foals, and if small often disappears without treatment by the time the horse is a two-year-old. Larger hernias, the ones where two or more fingers can be inserted into the defect, may require open or closed surgical repair.

Roaring. This is a wind (breathing) infirmity and is due to paralysis of the left vocal chord in the larynx at the top of the windpipe. Usually the vocal chords are pulled against the sides of the larynx when not being used for vocalisation purposes, but in the roarer, the paralysed chord and its cartilage partially obstruct the airway. This sets up a loud vibration which varies from a whistle to a roar heard initially only when the horse gallops, but it can progress to being audible at slower speeds. The condition limits the horse’s air intake and maximum ability to perform.

Various surgical procedures are used to rectify roaring. Roarers probably should not be bred from because of the genetic implications, though other factors have been incriminated such as size - very large horses are more prone to the condition.

Bleeding/EIPH. Exercise induced pulmonary haemorrhage (EIPH) means bleeding from the nose related to fast exercise, usually in racehorses. Horses with EIPH are known as bleeders and may show a trickle or a flood of blood at the nose after a gallop or race. Some do not show any, but a poor performance may lead to a veterinary examination which will pick up the condition. Bleeders are banned from racing for a period of time. If they bleed again they may be banned permanently. Theories about the causes of EIPH are constantly changing, but there is a genetic implication, also respiratory illnesses in young horses and dusty conditions may predispose.

Bleeding from the nose (epistaxis) may also be due to external trauma or polyps.

Bad temperament. Undoubtedly, the temperament of all animals is more a result of how they are treated than a coding in their genes. What are known as environmental factors are more significant than heredity in determining whether a horse will be easy or difficult to manage. But there are horses born with uncertain temperaments, or “born bad” as people say. Some strains or lines are noted for the trait but continue to be bred from because their desirable qualities outweigh the temperament problems.

Bad temperament should never be confused with the natural high spirits of the well-fed and willing horse. Genuine bad temper is best defined as deliberate biting, kicking and striking combined with untrustworthiness. Showing the white of the eye can indicate mean-spiritedness (or fear), though not in Appaloosas. But laid back ears, teeth baring and attempts to snap, tail jamming and switching, and turning the hindquarter are all threat manifestations of bad temper. Under saddle the horse might buck, rear, run backwards, refuse to move, bolt, savage or kick other horses, or throw itself to the ground.

Always the question should be asked why the horse is exhibiting these behaviours. Perhaps badly fitting gear is causing it or too much confinement or stabling, or lameness or soreness, or overwork or poor management or discipline routines, or sheer incompetence on the part of the handler/rider and failure to establish a normal human/horse dominance hierarchy.

Body faults

Some undesirable body conformations include sway (dipped) back and its opposite, roach back, though these conditions may not affect performance. Ewe-neck (upside-down neck) on the other hand does affect performance because it leads to star-gazing and the horse is more difficult to control. The straight-shouldered horse, with or without a low wither, is jarring to ride and more prone to forelimb lamenesses. The long-backed, weak-coupled and short-crouped horse is most undesirable both aesthetically and performance-wise. A long, very sloping croup (goose-rumped) is not particularly pleasing to the eye, but does not seem to affect soundness or working ability.

Other undesirable body conformations include narrow chest, small girth and the self-explanatory herring-gutted. Head shape contributes little to ability (except perhaps in jumpers where narrower heads and more forward placed eyes may assist focusing), but some head shapes are more aesthetically pleasing than others and are often breed-specific. A large head and roman-nose would look awful on an arabian but could be quite acceptable on an Australian stock horse, in fact might even be described as “game”.

Bad legs can make or break a horse, both as a performer and as a breeding proposition. Unlike poor body conformation, leg faults cannot be concealed by fat, though they are not always glaringly obvious and it does take time and experience to recognise them instantly.

Why are good legs so important? Because thousand of kilograms of force are directed downwards through each leg when a horse works at speed - the faster the work, the greater the force. A limb and its tendons and ligaments are designed to take this force straight down the middle. Any deviation from the normal means part of the leg will take more of the force than it should, and this will lead to damage and breakdown. The forelimbs take 65% of the weight of the horse, which is added to greatly by the forces of propulsion, so sound forelimbs are more important than sound hindlimbs.

Base-narrow conformation. This is often a fault in wide-chested horses and means the horse stands with front feet closer together than they should be. Too much force is directed down the outside of the leg and can lead to the development of windgalls on the outside of the fetlock joints and eventually lameness. Windgalls are fluid-filled blemishes and do not themselves cause lameness, but are an indication that all is not well within the joint.

Base-wide conformation. The horse stands with front feet too far apart and is often narrow chested as well. It causes the same problems as base-wide conformation, but on the inside of the leg.

Pigeon-toed (toed-in). The horse stands with toes pointing towards each other, the forelimb moves in an outward arc with each step, and the hoof lands and breaks over on the outside of the toe which wears more and exacerbates the problem. Being slightly pigeon-toed is not unusual but it does place additional strain on the fetlock joints and is another cause of windgalls.

Splay-footed (toed-out). The opposite of pigeon-toed, the horse stands with front feet turned out and the limb moves in an inward arc with each step. This fault is worse than pigeon toes because contact (interference) with the opposite limb is highly likely, anywhere between the fetlock and coronet. Windgalls, ringbone and sidebone are problems that may develop. The mildly toed-in or toed-out young horse can be corrected by hoof trimming. The toed-out hoof is lowered on the outside, toed-in on the inside, thus encouraging the hoof to land square and break over properly at the front of the toe. In older horses the benefits of corrective trimming are debatable, because other structures in the leg have adjusted to the fault and it might create a lameness problem where previously none existed.

Bench (off-set) knees. A very common forelimb fault, though only one leg may be affected. The problem is not the knee so much as the cannon, which is set too far to the outside of the leg. This causes the inside splint bone to take too much of the downward pressure, irritating the periosteum and causing a painful lump known as a splint. Once past the swollen and painful stage splints do not cause a problem but do remain as blemishes. No topical application will reduce or remove healed splints, though they will become smaller in time if not reinjured. A predisposing cause of splints in young horses, whether they are bench-kneed or not, is too much lunging or any other form of tight circling work.

Calf knees (back at the knee). This means the knee is further back than it should be in relation to the cannon below it. It is the worst forelimb fault of all, particularly in racehorses or any other horse expected to work at speed. When a horse gallops the knee tends to bend back slightly anyway as each forelimb contacts the ground, and calf knees accentuate the problem. The end result is that the small bones in the knee become subjected to such severe backward force that they fracture. Chip fractures of the knee are quite common anyway in young Thoroughbreds asked to gallop too fast too soon, and if they are calf-kneed as well, they have little hope of staying sound.

Buck knees (over at the knee). This is the opposite of calf knees, meaning the knees are slightly forward. Very slight buck knees are not of major concern, in fact may even lessen the possibility of chip fractures. More severe buck knees in young horses often rectify themselves with age, but if not, they can lead to sesamoid problems later on.

Pastern faults. Correct pastern conformation is important for the comfort of the rider, efficiency of stride and, of course, soundness. Pasterns that are too upright produce a short, jarring, choppy gait that can lead to lameness and the formation of osselets on the fetlocks, or even navicular disease. Pasterns that are too long and sloping result in a low, sharply dropping stride that is not energy efficient and predisposes to bowed tendons.

Cow hocks. Cow hocks should more properly be called horse hocks, because most horses have inturned hocks to a slight degree. However, severe cow hocks are not desirable. They cause inefficiency in propulsion and perhaps spavin, a fluctuatingly painful swelling on the inner side of the hock.

Sickle hocks. Sometimes called curby hocks, sickle hocks are the worst hindlimb fault. When the horse is standing square with hocks properly underneath, the cannon is not perpendicular to the ground but slopes slightly forward, like a forward slash in keyboarding. The fault causes inefficiency in stride pattern and propulsion, also spavin and curb, the latter being a swelling behind the hock which is initially painful and remains as a blemish.

Camped-out (standing out behind). Horses with this fault cannot stand with their hocks properly underneath them - the hocks seem to be trailing out behind somewhere when the horse attempts to stand square. The potential problems are the same as for sickle hocks.

Straight behind (straight hind leg). The hind leg is more upright than normal and the main problem this can cause is stifle lock (luxating patella or patella lock). The knee cap (patella) slips off the stifle and prevents the horse moving the hind leg forward. It will release itself, usually after a few moments, but might recur immediately or not for a few days. Treatments include surgery or internal blistering, but many young horses will grow out of it.

Acquired unsoundnesses

Unsoundnesses may be acquired through accident or injury and most are more correctly described as blemishes, because often they do not interfere with a horse’s soundness for work.

Scars. The commonest cause of permanent scarring is fence injuries. Small scars should never be considered a fault, and even those that are quite disfiguring seldom hinder a horse’s usefulness, unless in such a position or so large that they interfere with skin or joint mobility or the fitting of tack.

Capped elbow (shoe boil). This only occurs in shod horses, it is a swelling of the point of the elbow caused by rubbing of the heel of the shoe when the horse lies down. It can be prevented by use of a doughnut boot buckled around the fetlock, or by altering the heels of the shoes. Capped elbows may resolve once the cause is removed or they can be drained, but may persist as a blemish.

Capped hock. A swelling on the point of the hock caused by the horse persistently kicking or rubbing its hocks against a stable wall. It is yet another manifestation of the stress syndrome associated with confinement. Also it may occur during float travel if the horse is not kept forward off the tail gate. It is treatable early but may persist as a blemish.

Windgalls (windpuffs). Fluid-filled swellings on the inside or outside of the fetlock joint often associated with poor conformation, as already described.

Splints. Swellings on the inside of the fore cannons, as already described. Splints are not always due to irritation of the periosteum but may be caused by external trauma, such as the horse hitting itself or running into an obstacle. The splint bone is often fractured in such cases.

Bowed tendons. If you run your hand down the back of the cannon in a normal, sound horse you might think you are feeling bone, but it is actually tendon. So tough and strong are these flexor tendons in the foreleg that it takes tremendous force to injure them, but it does happen during extreme or unusual exertion and probably when the horse is tiring. In racing parlance it is known as “doing a tendon”. The initial pain and swelling decrease over time but the bowed-out appearance of the tendons remains as a permanent blemish. Even though some horses with bowed tendons are returned successfully to the racetrack after treatment and a long spell, most are retired but often become sound enough for normal riding.

Blue eye. This is a localised scarring of the surface of the eye usually due to a healed ulcer. It is not a problem if only a small area is involved and the scarring is off-centre, but if it is over the pupil the horse may be blind in that eye. If the scarring is extensive enough it makes the whole eye appear blue, but this is not to be confused with the blue eye caused by a lack of pigment in the iris, as in cremellos.

Bucked shins (shin sore). Young human athletes will be familiar with the pain of sore shins and the condition in horses is much the same. Due to too much training too soon, particularly too much fast work, the periosteum covering the front of the cannon bone (shin) becomes irritated and inflamed. It is so acutely painful that the horse is likely to fall on you if you touch the area.

Rest is the main cure and plenty of it, up to six weeks. There is an unfortunate tendency to return horses to work too soon and the problem will recur. Though mainly confined to two-year-olds, shin soreness can occur in older horses that really pound the ground hard when they gallop, or are training on hard surfaces.

The fore hoof is larger and wider than the hind because of its greater weight bearing responsibilities. Some horses have a particularly wide, spreading sort of hoof (flat feet) which is more prone to cracks and stone bruising, but it is genetically inherited and not due to being reared on black soil country.

Sound leg conformation reflects in a well-shaped hoof that grows down evenly. Hoof growth is continuous, the horny material being worn away at the bearing surface unless the horse is on very soft footing, in which case trimming with hoof cutters or a rasp will be needed. Shoeing, often described as a necessary evil, prevents the hoof wearing away on hard surfaces and helps protect against injury and bruising. Leg faults often result in uneven hoof growth and wear. Corrective trimming in young horses can straighten some of these but this is a specialist area.

The hot-blooded horse evolved in a semi-desert environment and there is no doubt that their hooves do not appreciate being continually wet. Much like our own hands constantly in water, a bit of grease helps to waterproof them. There are a remarkable number of concoctions known as hoof dressings - some read a bit like the label on a Worcestershire sauce bottle - “made to the secret recipe of a nobleman in the country” sort of thing. However, their most important ingredient is usually some sort of animal fat, such as neatsfoot oil, “horse” oil or mutton fat.

Weekend hacks with good sound hooves ridden mainly on grass do not need shoeing. The trick is not to trim them too much, meaning a decent amount of hoof is left all round and the edges are kept neat and not allowed to split. Clip-on boots (Easyboots) can be a worthwhile investment for occasional riding.

Parts of the hoof

Sole. Also hard and insensitive but not as thick as the wall. Ideally the sole is slightly concave and should never be in contact with the ground. The surface continually sloughs off to be replaced by new material from underneath, and should never be trimmed away with a shoeing knife.

Frog. A hard rubbery structure that is partly anti-concussive and partly an anti-slip devise. It was once thought that the frog acted as a pump to return blood back up the leg, but expansion and contraction of the heels (or the whole hoof if unshod) is the more important mechanism.

Bars. These are ridged, thickened parts of the sole and act as stabilizers for the hoof. Never should they be cut away or trimmed.

White line. This pale line between the wall and the sole indicates the junction between the sensitive and insensitive parts of the hoof. The white line is sometimes called the blacksmith’s landmark because it is the inner limit of where nails can be safely driven.

Coronet. The coronet or coronary band is the area from which the hoof wall grows. If damaged there will be a defect or crack in the wall below. A horizontal ridge slowly progressing down the hoof wall indicates the horse had a change in diet or an illness some weeks or months previously.

Common hoof problems

Nail bind (close shoeing). This is one of the commonest reasons for horses being lame a few hours or even a day after shoeing. It is caused by a nail being driven too close to the white line and thus the sensitive tissues of the hoof. If nail bind is suspected the shoe should be removed. Often the horse will be sound again almost immediately.

Bruised sole (stone bruise). Lameness associated with bruising of the sole can be a sign of early laminitis, or it may due to the horse standing on something sharp like a stone. The possibility of laminitis being the cause should be eliminated before proceeding with any treatment. If the bruising is due to external trauma, gently shaving away some of the bruised area with a hoof knife will relieve the pain. In the anterior toe region, bruising can be caused by pressure from the inner surface of the shoe, requiring it to be bevelled. Bruising closer to the frog is a definite indication that laminitis could be developing.

Corns. Corns are a bruising of the sole adjacent to the heels (seat of corn). They are the result of shoes being left on too long and the heels turning in and pressing on this area of the sole. Reshoeing usually rectifies the condition. Occasionally in unshod horses a similar problem can be caused by the wall at the heels curling in and trapping dirt or small stones.

Hoof cracks. These are splits in the hoof wall due to injury of the coronary band or because the hooves need trimming, particularly the removal of flares. Filing across the top and trimming the bearing surface beneath the crack will help them grow out. Some cracks require specialist veterinary or farriery attention, particularly if deep or causing lameness.

Quarter cracks. Cracks or splits in the hoof wall between the quarter and the heel. Because the wall is thinner in this area, the piece of hoof involved often partially detaches from the underlying tissue and sticks out like a hang nail, frequently catching on objects in the environment and causing pain. If it is almost off, a quick determined pull with a pair of pliers will remove it completely, but be careful not to get kicked. Quarter cracks often simply grow back and may need specialist farriery.

Underrun sole. This is a common lameness in paddock horses, particularly after rain, which makes the soles softer and more easily injured by stones and other sharp objects, also horses like to gallop after rain and are more likely to suffer a penetration injury of the sole. The typical scenario is an acutely lame horse standing and pointing the affected leg, which may be quivering. It looks like a broken leg at first, but an examination of the under surface of the foot will reveal a bruised area and perhaps an obvious penetration point where a sharp object has pierced the sole. If the edges are gently pared away with a sharp shoeing knife, before long the horse will probably jump or flinch and some foul-smelling black fluid (pus) will hiss forth. Provided the drainage hole is kept open and the horse obviously relieved, no further treatment should be necessary. At some later date the whole of the sole may slough off, exposing a new one underneath. If the horse fails to recover as expected or the condition recurs, veterinary advice should be sought because the underlying cause could be laminitis. Sometimes an untreated underrun sole will break out at the coronet because the pus had nowhere else to go, and these cases too may require veterinary advice and further treatment.

Thrush. Thrush is an infection of the frog and the grooves beside it and smells absolutely vile. It is a sure sign that horses are being kept in dirty stables and yards, forced to stand in their own urine and manure most of the day. The obvious treatment is to move the horse to clean accommodation or into a paddock, then clean out the infected material in the hoof and paint with a drying and disinfecting agent. If the horse is lame, veterinary attention may be required.

White line disease (onychomycosis). This disease appears to be on the increase, it occurs more commonly in shod horses in damp conditions and usually first appears as a defect filled with crumbly material in the white line area of the toe (seedy toe). It might then spread a considerable way up the inside of the hoof wall to such extent that the hoof sounds hollow when tapped, and can lead to rotation of the pedal bone or founder, which of course is an extremely serious and life threatening sequel. Several species of common soil-dwelling fungi are found in the decaying material but are probably secondary invaders. It is thought that mechanical stresses instigate the disease, including excessive toe length, hoof cracks, chronic laminitis, poor trimming and shoeing techniques. Treatment involves resection (removal) of the hoof wall over the affected area, application of antifungal agents and specialist shoeing.

Founder (laminitis). Founder is the “sinking” of the third phalanx (pedal bone, or bone in the foot) and is a sequel to laminitis. Acute laminitis is a medical emergency and prompt veterinary attention should be sought if founder is to be prevented. Sudden grain engorgement is a common cause. Typically the story is that the horse breaks into a feed shed, gorges on grain and before long is in extreme pain - evidenced by obvious distress, sweating, muscle tremors and rapid breathing. The pain is coming from the feet and, if not actually lying down, the horse will shuffle in an agonised way from one foot to the other. Usually the front hooves are the worst affected so that the horse may be standing with hindlegs well underneath in an effort to take the weight off the forelegs, which are extended forward. Signs of less acute or early laminitis include a red white line, sole bruising and a stiff or stilted “walking on eggs” gait that may look like shoulder lameness.

Laminitis is a possible sequel to any illness or infection, e.g., colic, pneumonia, septicaemia, toxaemia resulting from retained afterbirth, also it can have a mechanical cause as in road founder, common in the days before mechanization - “the ’ammer ‘ammer ‘ammer on the ‘ard ‘ard road”. Overweight and underexercised horses, particularly ponies, can founder spontaneously, also poor shoeing and trimming methods and shoeing too young have all been implicated. Other suspected causes include long hours of transport without exercise breaks.

The main aim of treatment is to relieve the pain as quickly as possible then stabilize the pedal bone with a heart bar shoe to prevent it rotating downwards and penetrating the sole. Prompt and effective treatment can return the horse to full function. The job of the owner if laminitis is suspected is to call for professional help straight away and start hosing the feet or stand the horse in water if that can be done without forcing the horse to move. Packing the feet in ice is a recently recommended treatment. In the old days when there was no other treatment available, horses sometimes recovered if kept standing in mud for several days. Chronic laminitis or founder is old founder, meaning the horse survived an acute attack in the past. It is evidenced by periodic bouts of lameness, sole bruising and abscessation (which may be due to other causes), white line disease/seedy toe, heavy rings around the hoof and eventually a slipper shape to the whole foot - it elongates, narrows and curls up at the toe.

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