Surgical shoeing is usually carried out by a competent horseshoer working in conjunction with a veterinary surgeon.
The veterinary surgeon, being scientifically trained in anatomy, physiology, and conforma tion of the horse, can explain to the shoeing smith the parts of the diseased foot capable of bearing weight, and the parts to be protected.
Surgical shoeing may be utilized to remove or reduce defects in the limbs due to faulty con formation; to prevent injuries; and to remove the causes of many forms of lameness. By applying a shoe so as to modify the distribution of the body-weight on a foot, or by protecting injured portions of the foot, horses which would otherwise be useless are rendered workable.
Stumbling.Stumbling, a defect in horses, is usually due to fatigue, over-driving, staleness, etc., but is sometimes also due to neglected or bad shoeing.
Stumblers from whatever cause are improved by shortening the toe of the front feet and applying a shoe with a rolled toe.
A most useful shoe of this type is the Fitz wygram shoe (Fig. 346). This is a concave shoe. The bearing or hoof surface is flat. The branches of the shoe narrow towards the heels. At the toe the shoe is thinned and rolled upwards, this rolling forming more or less of a broad clip. The ground surface of a newly applied Fitzwygram shoe has the appearance of an ordinary shoe three parts worn.
Owing to the difference in the width of the web between the toe and heel and the dishing out of the ground surface, this shoe is difficult to make. The principal advantage of the shoe is the upturned rolled toe, and this toe may be made on ordinary shoes. An ordinary shoe with a Fitzwygram pattern of toe is most effective in reducing the liability to stumble in stale and worn horses, and it also increases the wearing life of the shoe.
Forging or Clicking. When the toe of the hind shoe strikes the ground surface of the fore shoe and causes the noise so much disliked by horsemen it is called forging. Forging may be due to bad conformation, fatigue, over grown feet, or neglected shoeing. When a horse forges the hind foot is approaching the end of its flight before the fore foot has left the ground. To prevent this the horse should be shod so that the action of lifting the fore foot from the ground is quickened and that of the hind foot is delayed.
Slight cases of forging can be improved by reducing the toe of the front foot and applying a closely-fitting concave shoe with a rolled toe and bevelled heels. If the horse continues to forge, the toe of the front foot should be reduced as low as possible and the heels spared. It may even be necessary to apply calks to the front shoe. The posterior face of the calks should be bevelled downwards and forwards. The raising of the heels facilitates the quick picking up of the fore feet. In shoeing the hind foot of horses that forge the forward action is delayed by sparing the toe and reducing the heels. The shoe should be flat with square toe and quarter clips. The ground surface of the shoe should be well rounded at the toe. In fitting, the shoe should be set back at the toe so that the wall protrudes beyond the shoe at that point. The longer the heels of the hind shoe the more readily the foot is put down, as the heels of the shoe trail on the ground just before the foot alights. Another form of hind shoe which is successfully used to prevent forging is the diamond-toed shoe (Fig. 347). The ground surface of this shoe is bevelled downwards and backwards at either side of the toe. The depth of this shoe at the heels is about inch less than at the quarters. Two quarter clips are drawn.
The square-toed and diamond-toed shoes are a great disadvantage in some cases, especially in sickle-hocked or curby horses; owing to the reduction of the heels there is too great a pitch thrown on the foot axis, thus causing a great strain of the posterior part of the hock joint and the flexor tendons.
Over-reach. This is the name given to an injury produced at the heel of the fore foot by the shoe of the hind foot. Occasionally over reaches occur above the fetlock at the back of the fore leg. The injury may vary in degree from a slight bruise to a severe wound involving the subcutaneous tissues. When the skin is broken there is usually an underlip of skin hanging downwards.
Over-reaches usually occur at a gallop, but are sometimes seen in fast trotters.
Horses liable to over-reach should be shod with concave hind shoes. The borders of the hind shoe should be well rounded at the toe. The hind shoe should be so fitted to the foot that the wall at the toe protrudes over the shoe.
Brushing; Cutting; Interfering.A horse brushes or interferes when the hoof or shoe in motion strikes the opposite leg, usually the fetlock. The injury caused varies in degree from soiling of the hair to deep wounds.
In the case of the fore limbs, when the foot in flight strikes the opposite leg at the knee it is known as speedy cutting. Interfering may be due to had conformation, weakness, indif ferent shoeing, or overgrown feet.
To prevent interfering it is important to pay particular attention to the conformation of the limbs, style of gait, and to detect the part which inflicts the injury. In addition the nature of the work performed by the horse must be taken into consideration. No definite pattern can be laid down as an all-round anti-brushing shoe, because the horse may strike the opposite leg with the toe, quarter, or heel.
Brushing is commonly seen in horses in which the inner half of the hoof or shoe is lower than the outer, this causing the fetlock to be bent inwards and getting in the line of flight of the opposite foot. In such cases you prepare and shoe the hoof of the injured leg by giving the hoof a level bearing and applying a shoe whose inner branch has a greater depth than the outer. The fetlock then assumes a more upright posi tion. As this form of brushing is usually bilateral, it is better to apply a"knocked-up"shoe to each hind foot. This shoe has four to five nails on the outer branch and two nails on the inner branch near the toe (Fig. 349). The shoe has a clip at the toe and outside quarter. The inner branch is again knocked up so that its height is at least one-eighth higher than the outer branch. The outside border of the inner branch is chamfered downwards and inwards. The hoof surface is horizontal while the ground surface may be flat or fullered. A small calkin on the outside heel, especially in carriage and riding horses, is an aid to prevent slipping. Care should be taken in fitting the outer branch. It should follow closely the direction of the wall. The outer branch of the shoe should be kept short, as a long heel tends to thrust the fetlock inwards.
For horses which strike the opposite limb with the inside toe of the shoe, it is necessary to apply a shoe with the inner branch straight from the toe to the inner quarter. The shoe is devoid of nail-holes at this part. The shoe is fitted full at the quarter and inside heel with two nail.
holes towards the inner heel and four nail-holes in the outer branch. The shoe is clipped at the toe and outside quarter. The striking part of the shoe should be carefully rounded in a down ward direction. In fitting, the hoof should project over the shoe at the striking part.
To those horses which strike with the quarter and heel it is most difficult to apply anti-brush ing shoes successfully. The most useful form of shoe is a feather-edged, the inner branch is devoid of nail-holes, with two nail-holes at the toe and three or four in the outer branch (Fig. 350). The feather-edged inner branch of the shoe has its outside border chamfered downwards and inwards; the lower edge is rounded off. This shoe has a clip at the outside quarter towards the toe and a small clip at the inner quarter towards the heel. In fitting, the latter clip is fitted hot and let into the wall so that it is flush with the wall, leaving no projecting edges. Generally speaking, the lighter anti-brushing shoes are the better. The heavier the shoe the more the tendency for the horse to get tired.
Shoes weighted on the outer branch tend to abduct the limbs during flight and so prevent brushing, but being difficult to make and apply they have never found much favour.
Knuckling. Knuckling over is usually due to a contraction of the posterior or flexor tendons, or to a bony growth (ringbone) which inhibits the free normal movement of the fet lock, pastern or coronary joint. It is occa sionally seen in horses affected with spavin.
Owing to the peculiar action there is a great amount of wear of the horn at the toe. The hoof assumes a stumpy and upright appearance. For this condition a shoe with a beak or projecting toe piece is the most suitable. The beak acts as a strong point of leverage and at the same time forms a good protection for the horn at the toe (Fig. 351).
By using a pointed beak the horse may injure himself, and if the toe is dragged the shoe is likely to be torn off. The beak should be curled upwards forming a ring, or it may be curled upwards and backwards toward the wall of the foot. The extremity is spread out disc-shaped and rests against the horn wall. By this means the liability of the shoe being torn off is de creased.
For young horses affected with contracted tendons the above form of shoe used without calkins is very useful. By its use there is a steady tension on the back tendons, which tends to elongate them.
Laminitis. Laminitis is an inflammation of the fleshy leaves or sensitive laminw of the foot. The front feet are more commonly affected.
In severe cases the form of the hoof becomes changed, the sole becomes flat or even dropped. If this takes place special shoeing is required to render the horse workable.
Animals affected with laminitis have a char acteristic gait. In moving the heel comes to the ground first, consequently the greatest wear of the shoe takes place at the heels.
For horses affected with chronic laminitis the best shoe is a seated-out rocker-bar shoe, clipped at either side of the toe (Fig. 352). The shoe is seated-out on its bearing surface to prevent pressure on the sole. The actual part of the shoe in bearing is the same width as the wall. The shoe is thinner at the toe and heels than at the quarter, thus forming a rocker or cradle shape.
Contraction of the Hoof.In contra cted feet the hoof becomes narrow at its posterior part. The buttresses press on the frog, which becomes atrophied. The contraction may affect one half of the foot, but is usually bilateral. Con traction is more common in fore than hind feet.
Paring of the bars, sole, and frog, or the rasping of the periople or outer layer of the wall, which induces drying of the horn, all favour contraction.
The first aim in the treatment of contracted feet is to endeavour to restore as far as possible the frog and plantar cushion to their full-grown normal size. This object is best obtained by shoeing the foot so that the frog and posterior part of the foot participate to a large extent in taking the weight; by the use of tips or half shoes which protect the bearing surface of the anterior half of the foot, but allow the frog and posterior parts of the foot to come in direct contact with the ground. By this method there is no restraint due to the shoeing on expansion taking place in the posterior part of the foot. This favours development of the frog, plantar cushion, and free natural movement of the lateral cartilages.
The tip may be made from an ordinary shoe by cutting off sufficient from the end of each branch, and the foot prepared so that the tip is let in flush with the bearing surface of the horn posterior to it to give the foot a level bearing, but tips thinned out gradually to the ends of the branches are as effective and easier to apply.
If the horse is being treated for contracted feet or working on paved streets it may be neces sary to protect the posterior part of the foot from too rapid wear, but at the same time dis tributing weight over that part. Under these conditions rubber bar pads with leather soles in conjunction with tips are most useful.
Various forms of shoes with mechanical devices to reduce or remove contraction of the hoof have been introduced from time to time.
The prevailing principle of these shoes is a, hinge at the toe, clips on the inner border of the shoe at the heels, and a spring or screw between the heels of the shoe to force them apart. These mechanical devices have never gained much favour. They are difficult and expensive to make, require constant adjusting, and are of doubtful value.
Sandcrack.A sandcrack is a split in the horn of the wall, commencing at the coronet and running downwards. The crack may be at the toe, quarter, or heel. As the bulk of the horn of the wall is produced by the coronary band, anything which weakens the horn-producing part of this band favours the formation of a crack, e.g. any injury to the band or undue strain thrown on any one part through unequal tread caused by bad preparation of the foot or uneven shoes. Sandcrack is also frequently seen in dry brittle hoofs.
The crack may be on the surface or may extend as deep as the sensitive lamina.
When shoeing for sandcrack one must aim at reducing or removing all movement at the edges of the crack. Remove pressure of the shoe opposite the part, and distribute the weight so that the frog and posterior parts are brought into direct bearing.
For all forms of sandcrack, whether at toe, quarter, or heel, the hoof should be so prepared as to give a level bearing. The axis of the foot when viewed from the side should be straight. For sandcrack at the toe a bar shoe should be applied so as to get the full benefit of frog pressure. Thus the heels tend to spread and the toe to become narrow and thus bring the edges of the crack together (Fig. 353).
The shoe should be clipped at either side of the toe, and the shoe"set out"for 1 inch to 11 inches opposite so that there is no direct bearing on that part. Nail-holes should never be driven at or near the sandcrack.
The disadvantages of a bar shoe are many. They are difficult to make and fix. They are heavier than the ordinary shoe, require more nails to secure to the foot, and are more liable to be torn off.
By using an ordinary shoe with a rubber bar pad one gets the advantages of the bar shoe without the difficulty of making and fitting and without the increased weight. For sandcrack at the quarter a bar shoe is also applied with one clip at the toe. No nails should be driven near the crack and the shoe should be"set out"for a space corresponding to the base of a triangle, one of whose sides is formed by a split in the hoof and the other side by a perpendicular line dropped from the highest point of the crack at the coronet. Having applied the shoe the edges of the crack should be further immobilized by clips placed across the crack. Further, a tarred bandage should be wound around the hoof to prevent grit entering the crack.
Corns. A corn is a bruise to the sensitive sole at the posterior part of the foot in the angle formed by the bar and the wall. Corns are in most cases due to pressure by the heel of the shoe on the seat of injury, this being due to in different shoeing or allowing the shoes to remain on too long before removing.
In shoeing horses with corn it is necessary first of all properly to prepare the foot; if the toe is overgrown it must be shortened to get a proper level bearing. Apply a shoe in which the wall opposite the corn is relieved of pressure.
If the corn is dry and not severe a three quarter shoe may be used. This shoe is made by cutting 1 inch to 1i inches off the heel (usually the inner) of an ordinary shoe. The of the shortened heel should be bevelled downwards and forwards (Fig. 3M). This shoe is simple to make and easily fitted to the foot.
It, however, reduces the area for the distri bution of the body-weight and has the further disadvantage of leaving the seat of corn exposed and liable to injury from loose stones or uneven surfaCes on the roads.
By the use of a bar shoe (one with a trans verse bar between the heels) the frog is brought into bearing and takes a proportion of the body weight. This develops the frog and decreases any tendency to contraction at the heel. The wall opposite the corn may be relieved of pres sure by"setting out"the shoe at this part. The bar shoe is made of a longer length of iron than an ordinary shoe. In making the shoe the extra length of iron forms a prolongation of the heels. The shoe is shaped and fitted to the foot as for an ordinary shoe, and then the extra length at each heel is turned at right angles towards each centre, where the ends are welded. The web and thickness of iron in the bar should equal that of the branches of the shoe. The posterior edge or border of the bar should be bevelled downwards and forwards. Except in special cases the bar should have a horizontal foot surface and should take its bearings on the bulbs of the frog. In some cases, such as a contracted foot with suppurating corn, it is necessary to use a bar shoe with the inner heel removed. This is known as a three-quarter bar shoe. The inner heel is removed as in a three-quarter shoe (Fig. 355). With this shoe one has the advantage of being able to apply local dressings to the affected area without re moving the shoe. The free end of the bar and the free end of the inside branch of the shoe should be sloped off, this reducing the liability of the shoe being thrown off.
In a case of double suppurating corn on one foot a tip with a frog-bearing plate is applied. This is known as an anchor shoe. The toe and frog take all the weight, the affected parts are kept free of contact with the ground. This shoe is only used on horses being treated and kept in the stable. It is apt to be torn off during movement.
Sprained Tendons. — Sprain of the flexor tendons at the back of the leg below the kne( and hock joints is not uncommon in the horse.
In the acute stage when there is severe lame ness the animal is greatly relieved by raising the hind part of the foot, which removes a certain amount of tension on the tendons.
The most suitable shoe for this purpose is one that has both heels"knocked up"—a wedge heeled shoe (Fig. 356). The height of the heel varies according to the degree of severity of the case. It varies from 1 to 1 inches. The shoe has two quarter clips and six-nail-holes. When fitted to the foot the whole of the under surface of the shoe should touch the ground. Prolonged use of this form of shoe for strained tendons induces chronic contraction; when the inflammation has subsided a flat shoe should be applied.
A wedge-heeled shoe for strained tendons is much superior to one with calkins of the same height of heel, because the latter are more liable to sink into the ground, thus neutralizing the height effect, and the distribution of weight is not so even as it is with the wedge-heeled shoe, which has the whole of the ground surface in contact.
Wedge-heeled shoes are similarly useful in the early treatment of curb.
For partially ruptured tendons Patten or Crutch shoes are used. They are only used on animals being rested and treated in the stable. The patten is like an inverted staple. It is attached to the heels of the shoe to increase the height. The patten may be 2, 3, or even 4 inches high. The shoe is first fitted to the foot and the patten is then welded on at such an angle that the under border of the patten rests level on the ground when the shoe is nailed on. The web of the patten should equal the web of the shoe. The patten may be made detachable by tapping and screwing a hole in each heel of the shoe, and attaching the patten with small bolts. By this method pattens of varying heights may be applied without re moving the shoe as the case progresses.
For those animals in which there is a complete rupture of the tendons and the posterior point of the fetlock descends almost to the ground a shoe with a swan neck support is necessary. The shoe with prolonged heels is first fitted to the foot and the support either welded or screwed on afterwards. The support is really a continuation of the heels of the shoe upwards to the height of a point of the fetlock in its normal position. It is then bent at right angles backward for about 2 inches, where it forms a platform on which the fetlock rests. The branches are then continued downwards and backwards and the ends joined by a transverse bar (Fig. 357). The top of the arch on which the fetlock rests is usually padded to prevent chafing. This shoe and support is only used on an animal kept tied up in slings during treatment. It is an advantage to have the support detachable as it may be easily removed and its height varied according to require ments.
If the disease is not extensive a bar shoe may be employed, the diseased region relieved of all pressure, and the affected area treated anti septically.
In the more severe forms where the disease extends upwards towards the coronary band it is necessary for successful treatment to have the whole of the loose wall covering the affected area removed. A bar shoe with a false wall which is like a huge clip covering the whole diseased portion is used. The false wall or clip is made of sheet iron i-inch thick and welded on to the shoe. It is notched at intervals of an inch to facilitate the shaping of it to the outline of the foot. It is fitted hot. If there is sufficient bearing surface to carry the shoe the horse may be worked (Fig. 358).
Many different forms of horse-shoe pads have been introduced, made of various materials such as rope, oakum, leather, rubber, canvas, cork, felt, wood, etc.
The most practical pads are made of rubber. The rubber pads most commonly used are of the bar type—a leather sole, to which is attached a rubber pad, is used in conjunction with a short shoe. With this pad the hole of the foot is covered, the leather lies between the shoe and the foot.
A most useful pad is Gray's Bridge bar pad. This pad is composed of a thin steel plate to which is attached a bar of rubber. The pad is placed between the heels of the shoe and forms a bar. By its use one gets all the advantages of a bar shoe, and it has the further advantage of being lighter, prevents slipping, and reduces concussion.
When applying rubber pads they should never protrude beyond the ground surface of the shoe. They should be of such a thickness as to strike the ground at the same time as the shoe. Rubber alone is not an effective anti-slipping material, but the combination of rubber and iron is most successful.
Rubber pads are most useful in surgical shoeing. They may be used in the treatment of corns, fiat or dropped soles, weak heels, seedy toe, and sandcrack. Pads should not be used on horses affected with lameness due to side bones, or in cases of canker of the frog.