A Text-Book of Horseshoeing
by A. Lungwitz and John W. Adams Copyright 1897
B. Disturbances of Continuity of the Hoof.
Interruptions of continuity of the wall extending in the direction of the horn-tubes are known as cracks or seams. They have, according to their location, degree, and extent, not only various names, but also a varying significance.
Occurrence. — On the inner side of front hoofs, especially of horses that stand base-wide; on hind hoofs, usually at the toe.
Classification. — According to location we distinguish toe-cracks, side-cracks, quarter-cracks, and bar-cracks. Those cracks which affect only the upper border of the hoof are called coronary cracks; those which are limited to the lower border of the hoof are sometimes designated low cracks (plantar cracks); while those which are continuous from one border to the other are called complete cracks. If the crack passes through the entire thickness of the wall to the sensitive tissues underneath, it is called a deep or penetrating crack, in contradistinction to the superficial crack (Fig. 216).
Causes. — There are many. Besides wounds of the coronet, everything that impairs the elasticity of the horn, weakens the hoof, and causes an overloading of one-half of the hoof. Furthermore, great dryness and excessive work on hard streets.
Prognosis. — This will depend upon the age, kind, and location of the crack. A low crack is without significance unless it is the remnant of an old coronary crack which has grown down. Coronary cracks, on the contrary, are more serious because of the lameness which often accompanies them, and especially on account of the long duration of the healing process.
The borders of the crack never grow together, and healing can only take place through healthy, unbroken horn growing down from the coronary band.
(a) Treatment of Coronary and Bar-Cracks. — If practicable, allow the affected horse to go barefoot; otherwise, the use of the bar-shoe for all cracks is advised, because it will continuously protect the diseased section of wall from pressure by the shoe. If there are present still other diseases of the hoof (corns, contraction, flat or full hoof), the addition of a leather sole with packing will be most beneficial, not only in favoring the healing of the crack, but also in improving the form of the hoof and in favoring the cure of the other lesions. In all coronary cracks it is of advantage to assist healing by fastening or immobilizing the borders of the crack by one of the following methods:
1. By rivets (nails), which pass across the crack through holes previously drilled in the horn (Fig. 217).
2. By clamps or hooks, which by means of special pincers are forced into pockets previously burnt into the horn on opposite sides of the crack (Fig. 219, B).
3. By a thin iron plate placed across the crack and secured by small screws, such as are used in wood (Figs. 220, 221).
4. By means of a bandage to last one shoeing.
Toe-crack occurs most often in draught-horses and most frequently in the hind feet. In shod hoofs it starts at the coronary border, and unless proper treatment is instituted soon reaches the plantar border. Long toes and low quarters and excessive dryness of the horn are predisposing causes. The exciting cause is usually forward pressure of the upper end of the short pastern against the thin upper edge of the wall of the toe. In the last part of the phase of contact of hoof with ground the pasterns are upright, or may even incline downward and backward (foot axis broken strongly backward), the short pastern presses the coronary band firmly against the upper thin edge of the toe, when if brittle through dryness it is unable to stretch and tears asunder. Thus, under the effort of starting a heavy load, when a horse with all four legs flexed has risen upon the points of his toes, a short quick slip followed by a catch, will frequently start a crack at the coronet.
The hoof should be so dressed and shod that the foot-axis shall be straight when seen from the side. In hind feet it is admissible to break the foot axis slightly forward. Therefore, shorten the toe and spare the quarters. If the latter are deficient in length, raise them by swelling the branches or by low heel-calks.
The shoe may be open, or a bar-shoe, or a short shoe with a rubber frog and buttress-pad. Whatever expands the quarters closes a toe-crack. The Defay’s shoe (Fig. 206), or the Chadwick spring beneath a rubberpad, or beneath a bar-shoe with leather sole, if the frog be much shrunken, will be of service. The shoe should fit air-tight, except for an inch or so on both sides of the crack. Two lateral toeclips (Fig. 217) are drawn up, and the wall between these clips is cut down from a twelfth to an eighth of an inch.
After the shoe has been nailed on tight the toe-crack should be immobilized. The best method is by buried nails. Slots are burned or cut on opposite sides at a distance of an inch from the crack. With a spiral drill (see Fig. 218) bore a hole from a slot at right angles to the crack. Make a similar hole on the opposite side. Make the holes continuous by introducing a straight hot wire. The rivet may be an ordinary round wire nail which has been softened by bringing it to a yellow heat and allowing it to cool slowly. It is driven through and the ends firmly clinched. Such a nail is easily placed, need not press upon fleshy leaves, can not be stripped off or lost, and holds fast. The horse should stand on the foot while the rivet is being clinched. Two are sufficient for a complete crack (Fig. 217).
A more rapid, though less efficient method of immobilizing a toe- or a quarter-crack is by the use of the Vachette hook. A special apparatus is required (see Fig. 219). The burning iron (Fig. 219, A) is brought to a yellow heat, its end applied to the wall so that the two ears are on opposite sides and equidistant from the crack, when it is pressed firmly till the shoulder (Fig. 219, b) touches the surface of the wall. A Vachette hook, the distance between the points of which equals the distance between the ears of the firing iron, is seized by the special pincers (C), pressed into the slots burned to receive it, and is then driven into the horn by compressing the pincers. At the toe these hooks are frequently stripped off by the heels of the opposite shoe (in hind feet). Free application of hoof ointment, and maceration of the horn by melting snow or mud tends to loosen them so that they often drop out.
An efficient method of fastening either a toe- or a quartercrack is by using a metal plate one-sixteenth (1/16”) of an inch thick, provided with four to eight holes for the reception of screws four- to five-sixteenths of an inch long. The plate is heated, bent to conform to the curvature of the wall and pressed against the horn till it burns a bed for itself, when it is screwed fast. It will not loosen (see Fig. 220, b). In every complete crack of the wall the growing down of coherent horn is favored by thinning the horn for an inch on both sides of the crack directly over the coronary band (see Fig. 221, a), so that any gliding movement between the sides of the crack below can not be transmitted through the thinned area to the crack in the velvety tissue of the coronary band. Cutting a “V” at the coronet acts similarly, but is less efficient.
Quarter-crack is usually associated with contraction of the heels. It occurs on the inner quarter of base-wide (toe-wide) hoofs, and rarely in the outer quarter of base-narrow hoofs. For quarter-cracks we use a bar-shoe and determine the extent of the wall to be laid free in the following manner: We imagine the crack to be prolonged in the direction of the horn tubes to the plantar border, and drop a perpendicular line from the upper end of the crack to the plantar border. That part of the plantar border lying between these two points is then to be lowered sufficiently to prevent pressure from the shoe until the next shoeing (Figs. 220, a, and 221, c).
This method should be followed even when the perpendicular line falls behind the buttress.
The crack may be immobilized by the metal plate, or by narrow ticking bandage or adhesive tape wound a half dozen times around the hoof, in conjunction with a bar-shoe, Chadwick spring, leather sole and tar and oakum sole-packing.
In dressing the hoof, the side containing the crack should be spared, the opposite side lowered, the object being to shift the weight and consequent expansion into the sound quarter. When the affected quarter is deficient in length the branch of the shoe beneath should be made thicker, even to the extent of causing it to ground in advance of the opposite branch.
Next to shoeing, rubber hoof-pads render good service, because through them a part of the body-weight is distributed over the sole and frog. They assist in widening the hoof, and lessen shock when the foot is set to the ground. These are all matters which favor the growing down of unbroken horn.
When the crack gaps widely, and the frog is small and deep in the foot a shoe with bar-clips (Defay’s shoe), or a Chadwick spring, with bar-shoe and leather sole may be used. It is not impossible, indeed, to obtain a cure by using an ordinary open flat shoe, though much will depend upon the other lesions that may be present, the nature of the hoof, and the service required of the animal.
If the edges of the crack are irregular and overlapping, they should be carefully thinned away. Thinning the horn on both sides of the crack over the coronary band, preventing drying out of the horn, and frequent applications of carbolized oil to the coronet favor growth of undivided horn and guard against a renewal of the crack.
If in the beginning of the disease there is inflammation and lameness, cooling poultices should be used for several days. When there is no lameness, the horse may be used for slow draft purposes. Coach- and saddle-horses should be kept from fast work until sound horn has grown down at least one-half of an inch from the coronet.
Bar-cracks are usually the result of changes of position of the quarters, and are just as frequently brought about by contraction as by leaving the quarters too high. We see them almost entirely upon the fore-hoofs. They seldom occur alone; but are usually accompanied by corns. When the crack extends to the pododerm there is a superficial inflammation of the pododerm and lameness. When treatment is not promptly begun the inflammation extends to the deeper layers of the pododerm, or, indeed, even to the plantar cushion, and gives rise to swelling of the bulb of the heel upon that side and to a well-marked lameness, which requires treatment by a competent veterinarian.
Ordinarily a bar-crack is only found by a close examination of the hoof after the shoe has been removed. In paring the hoof the crack usually appears as a dark streak, sometimes as a bloody fissure; not infrequently grayish hoof-pus is discovered in the depths of the crack.
The treatment must be directed towards favoring the growth of a continuous (unbroken) bar. This is accomplished by completely removing the edges of the crack, paring the horn of the vicinity very thin, and preventing the least pressure upon the wall of this quarter by the shoe, by lowering this quarter with the rasp and applying a bar-shoe with leather sole.
Following the removal of the edges of the crack there often appears, especially in stumpy hoofs, a deep groove; if the bottom of this groove is moist, we should pack it with oakum wet with a five per cent. solution of creolin or carbolic acid, and cover the oakum with wax (grafting wax). The cracks will return if the exciting causes cannot be completely removed.
(b) Treatment of Low Cracks (Plantar Cracks). — These cracks, occurring principally upon the hoofs of unshod horses, are the result of excessive sketching and bending of the lower border of the wall. Insufficient rounding of the wall with the rasp is largely responsible for them. An exciting cause in shod horses is the use of too large nails in shoes that are punched too fine.
Every coronary crack becomes in time a low or plantar crack, and this has an important bearing upon the prognosis, because a renewal of the coronary crack will be followed by a low crack.
In order to remove these cracks it is sufficient merely to shoe the horse. Upon shod horses they may be prevented by using properly punched shoes and thin nails. The lower border of the wall near the crack should be relieved of pressure by cutting out a half-moon-shaped piece of horn. To prevent the crack from extending farther upward we may burn a transverse slot at the upper end of the crack, in as far as the leafy layer of the wall, or cut such a slot with a small hoof-knife.
An interruption of continuity of the wall, at right angles to the direction of the horn-tubes, is called a cleft.
Clefts may occur at any part of the wall; yet they occur most often upon the inner toe and inner side, as a result of injury from sharp, improperly placed heel-calks. However, suppurating corns, or other suppurative processes situated at the coronet or which find their point of escape at the coronet, may from time to time lead to separations of continuity and the formation of horn-clefts.
Horn-clefts, though the result of lesions which are often very injurious and interfere with the use of the horse, are of themselves not an evil which can be abolished or healed by shoeing, although, in many cases, proper shoeing would have prevented them. A horn-cleft is not a matter for consideration by the shoer until it has grown down so far that it comes within the region of the nails.
In order not to disfigure the hoof unnecessarily, the horn below the cleft should be kept in place as long as possible by shortening the wall at that point, to remove shoe-pressure, and by driving no nails into it. If, however, the horn is loose and about to come away, it should be removed and the defect filled with Defay’s patent horn-cement.
3. LOOSE WALL.
Separation of the wall from the sole in the white line is called loose wall (Fig. 223, a).
Occurrence. — Frequent on the fore-hoofs of shod and unshod horses, and oftener upon the inner than upon the outer side. More rare on hind hoofs. Common-bred horses with wide and flat feet are predisposed to this trouble.
We distinguish superficial and deep loose wall; only the latter requires the shoer’s attention, because it leads to lameness.
Causes. — Walls which are very oblique (slanting); outward bendings of the plantar border of the wall; burning the horn with hot shoes; dryness; neglected shoeing; excessive softening of the horn with poultices, particularly of cow-dung; carelessness in preparing the bearing-surfaces of hoof and shoe in shoeing; uneven fitting of the shoe.
Treatment. — It aims to remove the lameness and to favor growth of coherent horn. In the first place the removal of the exciting causes, followed by proper shortening of the wall. We should apply a shoe whose bearing-surface inclines slightly downward and inward, is perfectly smooth, and wide enough to cover the wall, white line, and outer border of the sole; the iron should be only moderately warm. Where there is lameness we use a leather sole with packing, or a bar-shoe. The loose wall should be freed from shoe-pressure only when it does not extend far along the white line. When the separation is extensive the loose wall should not be lowered. The crack should be filled with wood-tar, crude turpentine, or soft grafting-wax.
If a loose wall occur upon the foot of a horse while running barefoot, all separated horn should be removed; if, on account of the nature of the ground, this seems to be impracticable, the hoof must be shod.
Care of the Hoof. — Shoe at least every four to five weeks. Preserve the pliancy and toughness of the horn by judicious moistening.
4. HOLLOW WALL.
A hollow wall is one in which a separation has occurred between the middle layer of the wall and the keraphyllous layer. This crack or separation always extends in the direction of the layers of the wall (Fig. 223, b).
Occurrence. — Quite rare.
We should suspect a hollow wall when a part of the wall rounds out prominently beyond the rest, and gives forth a hollow (resonant) sound when struck. The white line presents a crack, yet we should hesitate to form a conclusion as to the extent of the separation from the extent of the crack along the white line, since the latter may be considerably smaller. The separation extends higher up the wall than in the case of loose wall, frequently to the coronet. The cavity is usually filled with crumbling, disintegrated horn.
Hollow wall is not often accompanied by pain. Lameness may arise, however, if the hollow section of wall assists in bearing the body-weight, and if the animal does fast work upon paved streets.
Causes. — Mechanical influences resulting in chronic inflammation of fleshy leaves.
Treatment. — A cure is possible, but requires considerable time. In shoeing, which should always aim to relieve pressure from the hollow section of wall, we cleanse the cavity and fill it with oakum and tar, crude turpentine, or wax. Where the separation is very extensive we use a bar-shoe.
The time required for complete cure of hollow and loose walls will depend upon the height of the separation.
5. THRUSH OF THE FROG.
When the horny frog is ragged and fissured, and an ill-smelling, dark-colored liquid collects in the lacunae of the frog, it is affected with thrush. When thrush exists uninterruptedly for several months the perioplic band is irritated and forms rings of periople which assume an irregular course and cross the rings of the middle layer of the wall (Fig. 224).
The causes: uncleanliness, too little exercise in fresh air, excessive paring of the frog, and the use of shoes with calks by which the frog is permanently removed from the ground.
The consequences are, besides contraction of the hoof, soreness in travelling, a shortening of the step, and, occasionally, well-marked lameness.
Treatment. — Removal of all greasy horn from the frog, and of the prominent overgrown angles of the buttresses, thorough washing of the frog once or twice daily with a 5 per cent. creolin or carbolic solution, abundant exercise, and shoes without calks.