In order to understand the general principles of shoeing, a glance at the different parts of the hoof is necessary. The "wall" is that portion which surrounds the foot, and is alone seen when this is placed on the ground. It is fibrous in structure, the fibres passing from above to below, as they grow from where the skin terminates. Externally, these fibres are dense and resisting, but those nearer the interior gradually become soft and spongy. The growth of the wall is indefinite, it being the part which has to sustain wear through contact with the ground.
When the foot is lifted, the sole and the frog are seen on its lower or ground surface. The "sole" is usually more or less concave in a healthy foot. It is fibrous, like the wall, its fibres passing in the same direction; but they are much softer, and their growth is definite, they breaking off in the form of flakes when they have attained a certain length. The "frog" is a triangular mass of somewhat soft and elastic fibrous horn, situated at the posterior part of the sole. Like that part, its fibres are also of definite growth, and flake off in large patches from time to time.
The wall sustains weight and wear on all kinds of ground; the sole is adapted for sustaining weight, on soft ground more particularly; while the frog has a most important use in acting as a cushion to support the powerful tendon which flexes the limb, in diminishing jar, and in preventing slipping.
The unpared sole and frog of the healthy foot need no protection on any kind of soil. The flakes of loose horn on the former serve a very useful purpose in retaining moisture, and so keeping the solid horn beneath soft and elastic, while they act as so many springs when the foot is placed on projecting stones. The more the frog is exposed to wear, the larger and sounder it grows, and the better it is for the foot and limb.
The fore-foot is of more importance, in the matter of shoeing, than the hind one; inasmuch as it has to support much more weight, and is consequently more exposed to disease and injury.
The fore-foot, when well formed, is nearly, if not quite, circular; the hind-foot is somewhat oval, the frog smaller, and the sole more concave. When the hoof is shod the wall is not exposed to wear, and therefore would grow to an indefinite, and, consequently, most inconvenient length, if the shoe should chance to be retained too long, and the excessive growth of horn not removed. The sole and frog, on the contrary, never cause inconvenience, as their growth is limited.
What is required in shoeing, then, in principle, is merely protection from undue wear, with the least possible interference with, or disturbance to, the functions of the foot and limb. The excess in length of the wall must be removed at frequent intervals - between a fortnight and a month - according to the activity of the growth; but the sole and frog, if healthy, should not be disturbed. Not a grain of iron more than is absolutely necessary should be allowed as a protection; and this question of weight of shoes is an important one, especially with horses which are compelled to travel beyond a walk. There are no muscles below the knee and hock, and those which are chiefly concerned in the movements of the limb arise high up, and act upon short levers. An ounce weight at the shoulder or stifle, therefore, progressively and rapidly increases, until at the foot it has become several pounds. Therefore it is, that a shoe six or twelve ounces heavier than is absolutely necessary to protect the wall from wear, occasions a great waste of muscular power of the limb, and consequent fatigue. If we consider the rapidity with which the weight increases from the shoulder or hip towards the foot, the number of steps a horse takes in a journey of a few hours, and that there are four feet so surcharged, we shall gain some notion of the many needless tons which the animal has been compelled to carry, and the strain thrown upon foot and limb - a strain they were never intended, and are not adapted by nature, to bear. All shoes should, then, be as light as may be compatible with the wear demanded from them.
For all horses except, perhaps, the heaviest animals employed in drays and heavy waggons, the lower or ground face of the shoes should be concave, and the upper or foot surface plane, or nearly so. They should be retained by the smallest number of nails possible - six or seven in the fore-shoes and eight in the hind-shoes. Calks should never be employed for light horses. With the heaviest horses - the dray or waggon animals - it may be advantageous to have toe and heel calks to afford secure foothold.
The procedure in shoeing is simple in the extreme. When the old shoe is removed from the hoof, nothing more is required than to remove the excessive growth of the wall by means of the rasp, applied to the lower margin or ground, or sole border - not the front of the wall. The amount to be removed will depend upon the growth, and of this the farrier's skill in his art should enable him to judge. It is at the toe or front portion that the excess is usually found, and this should be removed until, in an ordinary hoof, when placed on the ground, the angle should be about 50° to 52°. The angle can be easily measured by the experienced eye. The sole or frog should not be touched, not even the loose flakes removed; and all the work ought to be accomplished by means of the rasp. Paring out and hacking at these parts with the drawing-knife should be absolutely condemned as destructive to the foot.
In reducing the wall to a proper length, care should be exercised in keeping both sides of the hoof of the same height; as, if one is left higher than the other, the foot, fetlock, and, indeed, the whole limb, will be thrown out of the perpendicular. This causes the horse to travel painfully, as it twists the joints, and in time leads to disease. Nearly always the inside of the foot is left higher than the outside, and this throws severe strain on the outside of the foot and fetlock. Standing in front of the horse when the foot is on the ground, one can perceive at once whether this deviation is present. In a well-formed foot and leg, a plumb-line should fall from the point of the shoulder through the middle of the knee, shank, pastern, and front of the hoof.
The wall having been reduced sufficiently, the shoe should fit full all round the circumference, and project slightly beyond the heels. Heat is not absolutely necessary in fitting it, or procuring accurate co-aptation between it and the hoof. The nails should take a short, thick hold of the wall, so that, if possible, the old nail holes may be obliterated when the excess of horn is removed at the succeeding shoeing. In the fore-foot the nails should be driven home more firmly at the toe than the heels, particularly the inside heel. The clinches must be laid down as smoothly as possible, and with only the most trifling rasping. The front of the hoof or wall should on no account be otherwise touched with the rasp, but ought to pass in a straight line from the top, or coronet, to the shoe. Rasping this part of the hoof is most injurious, and should not be. tolerated on any consideration. It removes the dense tough fibres which are best adapted for holding the nails that retain the shoe, and exposes the soft spongy horn beneath; this soon dries, cracks, and breaks, and does not afford sufficient support to the nails.
The evils of shoeing, as too often practised, are: - 1. Paring of the sole and frog; 2. Applying shoes too heavy and of a faulty shape; 3. Employing too many or too large nails; 4. Applying shoes too small, and removing the wall of the hoofs to make the feet fit the shoes; 5. Rasping the front of the hoof.
The shoe should give the hoof a level, natural bearing on the ground. Calkings are hurtful to fast-moving horses, and may be dispensed with if the shoes have a concave ground surface, and the frog is allowed to come fully in contact with the ground; if they are resorted to, their injurious effects should be averted by employing a toe-piece of the same height.
For the racehorse, the narrowest iron rim is sufficient, provided it is strong enough not to twist or bend, and to permit a grip of the ground. For hunters, hacks, and harness horses, a shoe of the modified pattern described, and here figured, is well adapted. Even the ordinary fullered hunting pattern, but without the calking on the hind shoe, is infinitely more preferable to that usually employed for hacks and harness horses. For these no better kind of shoe can be recommended than that recently introduced for troop, artillery, and transport horses in Her Majesty's Service. This is, in shape, based on the requirements pointed out, and which it meets in every particular. Since its introduction it has admirably fulfilled all the requirements of a perfect horse-shoe.
Hitherto great difficulty has been experienced in obtaining shoes of good material, uniform shape, and easy application. But the introduction of machinery into horse-shoe manufacture promises to revolutionise the farrier's art. The Horse-shoe and Nail Manufacturing Company, of London, * are now producing cold state, and put on in the stable or anywhere else without the aid of a forge; consequently, sending horses to the farrier's establishment can be dispensed with. These shoes are made of such good iron that they very rarely break; they can easily be altered in shape without heating, and are sold in all sizes.
* Offices, 115, Cannon Street, London, E.C horse-shoes which, for elegance, durability, and safety, are far superior to anything which has yet been made by hand, and at a much less cost. They are supplying shoes in large quantities, of the pattern we have described and recommended, to the army; and as these shoes are completely finished and ready for immediate application, the time required to shoe a horse is reduced by at least one-half - often a matter of some importance. Not only this, but the shoes can be fitted in a
Fore Foot. Pattern of Horse-Shoes in use in the British Army.
With regard to nails, all horsemen know how important it is that these should be of the very best quality and shape. The hand-made nails are often very inferior or uncertain in quality, and have to be hammered and pointed by the farrier before they can be driven into the hoof. This hammering and pointing require time, and are not always effected with skill; the surface of the nail is always uneven and ridged, which makes it more difficult to drive; and not unfrequently the point is too thin or unsound, which, in many cases, causes it to run into the living parts of the foot, or to break, producing serious results. The Globe horse-nail, which is also made by the above Company, is finished ready for immediate use, is perfectly smooth on its surface, strong at the point, and has withstood the most severe tests with regard to tenacity and durability; while, being made by machinery, it is always uniform in size and thickness, and does less harm to the hoof than the hand-made nail. These nails are made to fit exactly all the shoes manufactured by the Company, as well as the special shoes provided for the army horses.