A Text-Book of
by A. Lungwitz and John W. Adams Copyright 1897
This is the second part in what will be a complete reprint of Lungwitz & Adams’ important ‘Textbook of Horse-Shoeing’ originally written in the 1880’s and containing some remarkably modern information. This volume goes into the greatest detail on the subject and with an intelligent clarity that belies how old it is. Coming as it did at the end of the first horse era, and well before anyone might have reasonably predicted the advent of the automobile and tractor, it is apparent how important the equine was to the whole of society. The authors, of Germany and Pennsylvania, compiled what was, at the time, to be the ultimate word on the subject. As with all of the reprints we have offered over forty years time, we trust that readers will be triggered by these words to complete their education with diligence and introspection. Just because something is old doesn’t always make it right, and of course just because something is new doesn’t make it the true culmination either. LRM
F. Growth of the Hoof and Wear of the Hoof and Shoe.
All parts of the horn of the hoof grow downward and forward, the material for this growth being furnished by the remarkably large quantity of blood which flows to the pododerm. The growth of the hoof is regulated by the nerves.
As a rule, the hoof grows uniformly, — that is, one section of growth of the hoof is regulated by the nerves. A visible indication of growth is the increase in height and width of the hoof colthood to maturity.
The rapidity of growth of the wall varies, amounting in a month to from one-sixth to one-half of an inch. The average monthly growth in both shod and unshod horses of both sexes is, according to my own experiments, one-third of an inch. Hind hoofs grow faster than front hoofs, and unshod faster than shod. The hoofs of stallions grow more slowly than those of mares and geldings.
Abundant exercise, proper grooming (flexibility and moistness of the horn), regular dressing of the wall, and running barefoot from time to time favor growth; while little or no exercise, dryness, and excessive length of the hoof hinder growth.
The time required for the horn to grow from the coronet to the ground is, therefore, equally variable, and is, moreover, dependent upon the height (length of toe) of the hoof. At the toe the horn grows down in from eleven to thirteen months, at the mammae or sides in from six to eight months, and at the quarters in from three to five months. The time required for the renewal of the entire hoof we term the period of hoof renewal. If, for example, we know exactly the rapidity of the horn growth in a given case, we can estimate without difficulty the length of the “period of hoof renewal,” as well for the entire hoof as for each individual section of the wall. The duration of many diseases of the hoof (cracks, clefts, partial bendings of the wall, contractions, etc.) can be foretold with relative certainty only by knowing the period of hoof renewal.
Irregular growth sometimes takes place. The chief cause of this is usually an improper distribution of the body-weight over the hoof, — that is, an unbalanced foot. Wry hoofs of faulty positions of the limbs are often exposed to this evil; a faulty preparation of the hoof (dressing) for the shoe, as well as neglect of the colt’s hoofs, is in the majority of cases directly responsible for this condition.
If in the shortening of the wall a part is from ignorance left too long, or one-half of the hoof shortened too much in relation to the other half, the foot will be unbalanced. The horse will then touch the ground first with the section of wall which has been left too high, and will continue to do so until this long section has been reduced to its proper level (length) by increased wear which will take place at this point. In unshod hoofs this leveling process takes place rapidly; such, however, is not the case in shod hoofs, for here the shoe prevents rapid wear, and, indeed this leveling process is often rendered impossible through the welding of high steel calks to the shoe. If this fault in trimming be repeated at the next and the subsequent shoeings, and if the faulty relation of the ground surface of the hoof to the direction of the foot-axis remain during several months, the portion of wall left too high will grow more rapidly, the walls will lose their natural straight direction and become bent. If, for example, the outer wall has been left too long during a considerable period of time, a crooked hoof results (Fig. 85) in which the rings are placed closer together upon the low (concave) side than upon the high (convex) side. If for a long time the toe is excessively long, it will become bent; or if this fault affects excessively high quarters they will contract either just under the coronary band or will curl forward and inward at their lower borders. These examples are sufficient to show both the importance of the manner in which a horse places his foot to the ground and its influence upon the loading, growth, and form of the hoof.
Wear of the Shoe and of the Hoof upon the Shoe.
The wear of the shoe is caused much less by the weight of the animal’s body than by the rubbing which takes place between the shoe and the earth whenever the foot is placed to the ground and lifted.
The wear of the shoe which occurs when the foot is placed on the ground is termed “grounding wear,” and that which occurs while the foot is being lifted from the ground is termed “swinging-off wear.” When a horse travels normally, both kinds of wear are nearly alike, but are very distinct when the paces are abnormal, especially when there is faulty direction of the limbs. While in the majority of horses whose limbs have been stiffened by age and overwork both kinds of wear are most marked at the toe of the shoe, we see relatively fewer cases of the “grounding wear” at the ends of the branches (as in laminitis); on the contrary, we always notice “swinging-off wear” at the toe of the shoe. It is worthy of notice that length of stride has much to do with the wear. We observe that with shortening of the stride both kinds of wear occur at the toe of the shoe, and this is rapidly worn away, as is the case with horses which are fretful and prance under the rider, draw heavy loads, or from any other cause, as disease or infirmity, are obliged to shorten their steps. With increase of length of stride the wear of the shoe becomes more uniform.
The position and form of the shoe have a marked influence upon its wear; at the place where the shoe is too far under the hoof either as a result of shifting or of having been nailed on crooked, or where the outer branch has not the necessary width, or does not form a sufficiently large curve, the wear will be increased.
Also the relative length of side-walls, or of toe and heels, influences rapidity of wear of the shoe. If through ignorance or carelessness one side-wall be left too long, the branch beneath will meet the ground before other parts of the shoe and will wear faster (see Figs. 87, 88, 89).
The wear of the hoof upon the shoe occurs as a result of the movements of the quarters. Visible indications of this are the brightly polished, often sunken places upon the bearing-surface of the ends of the branches, showing that scouring occurs between the horn and the iron. Shoes which show brightly polished places in their anterior halves have been loose. The wear of the quarters upon the shoe is not always uniform, but is usually greater on the inner than on the outer quarter, especially in base-wide feet. The degree of this wear of the hoof may be from nothing to one-fourth of an inch or more from one shoeing to the next. Finally, we should remember that this usually invisible scouring away of the hoof gradually causes the nails at the quarters to become loose, and that this is more clearly marked in the front than in the hind hoofs.
G. Physiological Movements on the Hoof. (Mechanism of the Hoof.)
These movements comprise all those changes of position within and of the hoof which are brought about by alternately weighting and relieving the foot, and which are manifest as changes of form of the hoof. The following changes in form of the hoof are most marked at the time that the hoof bears greatest weight, — that is, simultaneous with the greatest descent of the fetlock-joint.
- A lateral expansion over the entire region of the quarters, occurring simultaneously at the coronary and plantar borders. This expansion is small, and in general varies between one-fiftieth and one-twelfth of an inch.
- A narrowing of the anterior half of the hoof measured at the coronary border.
- A decrease in height of the hoof, with a slight sinking of the heels.
- A flattening (sinking) of the sole, especially in its branches.
These changes of form are much more pronounced in the half of the hoof that bears the greater weight.
A hoof while supporting the body-weight has a different form, and the tissues enclosed within it a different position, than when not bearing weight. Since loading and unloading of the foot are continually alternating, the relations of internal pressure even in the standing animal are continuously changing, so that, strictly speaking, the hoof is never at rest.
The changes in form take place in the following order: the body-weight falls from above upon the os coronae, os pedis, and navicular bone, and at the moment that the foot is placed upon the ground is transmitted through the sensitive laminae and horny laminae to the wall. At the instant that the fetlock reaches its lowest point the os pedis bears the greatest weight. Under the body-weight the latter yields, and with the navicular bone sinks downward and backward. At the same time the upper posterior portion of the os coronae (Fig. 90, A) passes backward and downward between the lateral cartilages (a), which project above the upper border of the wall, and presses the perforans tendon down upon the plantar cushion. The plantar cushion being compressed from above, and being unable to expand downward, is correspondingly squeezed out towards the sides and crowded against the lateral cartilages, and they, yielding, press against and push before them the wall the quarters. The resistance of the earth acts upon the plantar surface of the hoof, and especially upon the frog, and it, widening, crowds the bars apart, and in this manner contributes to the expansion of the quarters, especially at their plantar border (see Fig. 90). The horny sole under the descent and pressure of the os pedis sinks a little — that is, the arch of the sole becomes somewhat flattened. All these changes are much more marked upon sound unshod hoofs, because in them the resistance of the earth upon the sole and frog is pronounced and complete. These changes in form are more marked in front feet than in hind. In defective and diseased hoofs it may happen that at the moment of greatest weight-bearing, instead of an expansion a contraction may occur at the plantar border of the quarters.
Three highly elastic organs there are which play the chief part in these movements, — namely, the lateral cartilages, the plantar cushion, and the horny frog. Besides these structures, indeed, all the remaining parts of the horn capsule, especially its coronary border, possess more or less elasticity, and contribute to the above-mentioned changes of form.
In order to maintain the elastic tissues of the foot in their proper activity, regular and abundant exercise, with protection against drying out of the hoof, are absolutely necessary, because the movements of the different structures within the foot and the changes of form that occur at each step are indispensable in preserving the health of the hoof. Long-continued rest in the stable, drying out of the hoof, and shoeing decrease or alter the physiological movements of the foot, and these lead under certain conditions to foot disease, with which the majority of horse owners are entirely unacquainted.
As an outward, visible indication of the mobility of the quarters upon the shoe we may point to the conspicuous, brightly polished, and often sunken spots, or grooves, upon the ends of the branches. They are produced partly by an in-and-out motion of the walls at the quarters, and partly by a forward and backward gliding of the quarters upon the shoe.
The benefits of these physiological movements within the hoof are manifold:
- Through them shock is dispersed and the body protected from the evil consequences of concussion or shock.
- These movements increase the elasticity of the entire limb and in this way contribute much to a light and elegant gait.
- They maintain a lively circulation of blood in the vessels of the pododerm, and this insures a rapid growth of horn.
Since it is a generally accepted fact that shoeing interferes with the physiological movements of the hoof, alters them, indeed almost suppresses them, and that all these movements are spontaneous and natural only in sound unshod hoofs, we are justified in regarding as a necessary evil. However, it is indispensable if we wish to render horses serviceable upon hard artificial roads. If, in shoeing, consideration be given to the hoof-surface of the shoe, the ends of the branches being provided with a smooth, level bearing-surface, which allows free play to the elastic horn capsule, in so far as this is not hindered by the nails we need have no fear of the subsequent disease of the hoofs, provided the horse is used with reason and receives proper care.