Diseases of the Horse's Foot Part 15

Above all, the heels of the shoe should be of full length, otherwise, if the shoe is worn just a little too long, its heels are carried under the sole of the foot, and by pressure there produce a corn.

If, with these precautions in shoeing flat-foot, tenderness still persists, a sole of leather or gutta-percha must be used with the shoe.

D. PUMICED-FOOT, DROPPED SOLE, OR CONVEX SOLE.

_Definition_.--This term is applied to the foot when the shape of the sole is comparable to the bottom of a saucer. When least marked it is really an aggravated form of flat-foot.

_Symptoms_.--In pumiced-foot the sole projects beyond the level of the wall. The obliquity of the latter is more marked than in the previous condition, and progression, to a large extent, takes place upon the heels.

In addition to its deformity, the horn is greatly altered in quality, and, as the name 'pumice' indicates, is more or less porous in appearance, bulging, and brittle.

_Causes_.--As a general rule, it may be taken that pumiced-foot is a sequel of previous disease, although in its least p.r.o.nounced form it may occur as the result of accidental or other causes, such as those described in the causation of flat-foot.

Occurring in its most marked form, there is no gainsaying the fact that pumiced-foot is a sequel of either acute or subacute laminitis. As we shall see when we come to study that disease, the dropping of the sole is brought about by distinct and easily-understood morbid processes affecting the sensitive structures. Briefly, these morbid processes in laminitis may be described thus: The acc.u.mulated inflammatory exudate, and in some cases pus, weakens and destroys the union between the sensitive and insensitive laminae. This separation, for reasons afterwards to be explained, is greatest in the region of the toe. The os pedis, loosened from its intimate attachment with the h.o.r.n.y box, is dropped upon the sole, and the sole, unable to bear the weight, commences to bulge below.

The altered character of the horn is accounted for by the inflammatory changes in the sensitive laminae and the papillae of the keratogenous membrane generally, for it follows as a matter of course that these tissues, themselves in a diseased condition, must naturally produce a horn of a greatly altered and inferior quality.

When following the _subacute_ form of laminitis, the changes characterizing pumiced-foot are slow in making their appearance. The animal at first goes short, and the lameness thus indicated gradually becomes more severe, until the animal is no longer able to work. The feet become hot and dry, the hoof loses its circular form, and the growth of horn at the heels becomes excessive. At this stage the appearance of bulging at the sole begins to make itself seen. Later, the outer surface of the wall becomes 'ringed' or 'ribbed,' the rings being somewhat closely approximated in the region of the toe, and the distance between them gradually widening towards the heels. The wall too, especially in the region of the toe, instead of running in a straight line from the coronary margin to the shoe, becomes concave. It is this change, together with the appearance of the rings, that indicates the loosening of the attachment of the os pedis to the wall, and its afterwards backward and downward direction (see Fig. 124).

[Ill.u.s.tration: FIG. 81.--HOOF WITH THE RIBS OR RINGS CAUSED BY CHRONIC LAMINITIS.]

As a sequel of _acute_ laminitis, these changes make their appearance with more or less suddenness, and are generally complicated in that they owe their occurrence to the formation of pus within the h.o.r.n.y box.

_Treatment_.--Pumiced-foot is always a serious condition. The animal is useless for work upon hard roads or town pavings, and is of only limited utility for slow work upon soft lands. The more serious form, that following acute laminitis, and complicated by the presence of pus, we may regard as beyond hope of treatment.

With the more simple form of the condition, we may do much to render greater the animal's usefulness. The same principles as were applied to the shoeing of flat feet will have to be observed here. Tr.i.m.m.i.n.g or paring of any kind, save 'straightening up' of the wall, must be severely discountenanced. A broad-webbed shoe, one that will give a certain amount of cover to the sole, is indicated. As in the treatment of flat-foot, however, direct pressure upon the sole must be avoided, and the shoe 'seated.' The 'seating,' however, should not commence from the absolute outer margin of the shoe's upper surface. A _flat_ bearing should be given to the wall and the white line, and the seating commenced at the sole.

We have already remarked on the increased growth of horn at the heels. It is in this position, then, that will be found the greatest bearing surface for the shoe, and it is wise, in this case, to have the heels of the shoe kept flat. In other words, the 'seating' is not to be continued to the hindermost portion of the branches of the shoe. By this means there may be obtained at each heel a good solid bearing of from 2 to 3 inches, which would otherwise be lost.

Where the accompanying condition of the horn is bad enough to indicate it, a leather sole should be used, beneath which has been packed a compress of tow and grease, rendered more or less antiseptic by being mixed with tar.

Where the sole is exceedingly thin, and inclined to be easily wounded, and where the hoof, by its brittleness, has become chipped and ragged at the lower margin of the wall, it may perhaps be more advantageous to use, in place of the compress of tow, the _huflederkitt_ of Rotten. This is a leather-like, dark brown paste. When warmed in hot water, or by itself, it becomes soft and plastic, and may readily be pressed to the lower surface of the foot, so as to fill in all little cracks and irregularities, and furnish a complete covering to the sole and frog, and to the bearing surface of the wall. When cold it hardens, without losing the shape given to it, into a hard, leather-like substance.

Treated in this way, the animal with pumiced feet may yet be capable of earning his living at light labour or upon a farm.

E. 'RINGED' OR 'RIBBED' HOOF.

_Definition_.--A condition of the hoof in which the wall is marked by a series of well-defined ridges in the horn, each ridge running parallel with the coronary margin. They are known commonly as 'gra.s.s rings,' and may be easily distinguished from the more grave condition we have alluded to as following laminitis, by the mere fact that they do not, as do the laminitic rings, approximate each other in the region of the toe, but that they run round the foot, as we have already said, _parallel with each other_.

[Ill.u.s.tration: FIG. 82.--HOOF SHOWING THE RINGS IN THE HORN BROUGHT ABOUT BY PHYSIOLOGICAL CAUSES.]

_Causes_.--This condition is purely a physiological, and not a pathological one, and the words of its more common name, 'gra.s.s rings,' sufficiently indicate one of the most common causes. Anything tending to an alternate increase and decrease in the secretion of horn from the coronet will bring it about. Thus, in an animal at gra.s.s, with, according to the weather conditions, an alternate moistness and dryness of the pasture, with its consequent influence on the horn secretion, these rings nearly always appear. The effects of repeated blisters to the coronet make themselves apparent in the same way, and testify to the efficacy of blisters in this region in any case where an increased growth of horn is deemed necessary.

From this it is clear that the condition depends primarily upon the amount and condition of the blood supplied to the coronary cushion. Thus, fluctuations in temperature during a long-continued fever, or the effects of alternate heat and cold, or of healthy exercise alternated with comparative idleness, will each rib the foot in much the same manner.

_Treatment_.--The condition is so simple that we may almost regard it as normal. Consequently, treatment of any kind is superfluous. Where const.i.tutional disturbance is exerting an influence upon either the quality or quant.i.ty of the blood directed to the part, then, of course, attention must be paid to the disease from which it is arising.

F. THE HOOF WITH BAD HORN.

(_a_) THE BRITTLE HOOF.

_Definition_.--As the name indicates, we have in this condition an abnormally dry state of the horn.

_Symptoms_.--These are obvious. The horn is hard, and when cut by the farrier's tools gives the impression of being baked hard and stony, the natural polish of the external layer is wanting, and there is present, usually, a tendency to contracted heels. With the dryness is a liability to fracture, especially at points where the shoe is attached by the nails.

As a consequence, the shoes are easily cast, leading to splits in the direction of the horn fibres. These run dangerously near the sensitive structures, giving rise in many cases to lameness. Even where p.r.o.nounced lameness is absent the action becomes short and 'groggy,' and the utmost care is required in the shoeing to keep the animal at work.

_Causes_.--To a very great extent the condition is hereditary, and is observed frequently in animals of the short, 'cobby' type. In ponies bred in the Welsh and New Forest droves the condition is not uncommon, especially in the smaller animals. Animals who have had their feet much in water--as, for instance, those bred and reared on marshy soils--and afterwards transferred to the constant dryness of stable bedding, are also particularly liable to this condition. It is noticed, too, following the excessive use of unsuitable hoof-dressings, more especially in cases where coat after coat of the dressing is applied without occasionally removing the previous applications.

_Treatment_.--As a prophylactic, a good hoof-dressing is indicated. It should not consist solely of grease, but should have mixed with it either wax, turpentine, or tar.

Above all, careful shoeing should be insisted on, and the owner of an animal with feet such as these will be well advised if he is recommended to have the shoeing superintended by one well competent to direct it rightly.

The foot should be trimmed but lightly, always remembering that in a foot of this description the horn, in addition to being brittle, is generally abnormally thin. Jagged or partly broken pieces should be removed, and the bearing surface rendered as level as possible. The foot should be carefully examined before punching the nail-holes in the shoe, and the nail-holes afterwards placed so as to come opposite the soundest portions of horn. The nails themselves should be as thin as is consistent with durability, and should be driven as high up as possible.

On the least sign of undue wear the shoes should be removed, never, as is too often done, allowing them to remain on so long that a portion breaks away. If, with the laudable idea of not interfering with the horn more than is possible, this is practised, the portion of the shoe breaking off is bound to tear away with it more or less of the brittle horn to which it is attached.

Where the breaks in the horn are so large as to prevent a level bearing for the shoe being obtained, the interstices should be filled up with one or other of the preparations made for this purpose. One of the most suitable is that discovered by M. Defay. By its means sand-cracks or other fractures of the horn may be durably cemented up.

'Even pieces of iron may be securely joined together by its means. The only precaution for its successful application is the careful removal of all grease by spirits of sal-ammoniac, sulphide of carbon, or ether. M. Defay makes no secret of its composition, which is as follows: Take 1 part of coa.r.s.ely-powdered gum-ammoniac, and 2 parts of gutta-percha, in pieces the size of a hazel-nut. Put them in a tin-lined vessel over a slow fire, and stir constantly until thoroughly mixed. Before the thick, resinous ma.s.s gets cold mould it into sticks like sealing-wax. The cement will keep for years, and when required for use it is only necessary to cut off a sufficient quant.i.ty, and remelt it immediately before application. We have frequently used this cement for the repair of seriously broken hoofs. It is so tenacious that it will retain the nails by which the shoe is attached without tearing away from the hoof.'[A]

[Footnote A: _Veterinary Journal_, vol. iii., p.71.]

Failing this, the bearing surface may be made level, and fractures repaired by using the _huflederkitt_ described in the treatment of pumiced sole.

(_b_) THE SPONGY HOOF.

_Definition_.--This is the opposite condition to the one we have just described, and is characterized by the soft and non-resistant qualities of the horn.

_Symptoms_.--Spongy hoof is quite common in animals that have large, flat, and spreading feet--in fact, the two appear to run very much together. It is a common defect in animals reared in marshy districts, and of a heavy, lymphatic type. The Lincolnshire Shire, for instance, has often feet of this description, and, the causative factors being in this case long-continued, render the feet extremely predisposed to canker. The horn is distinctly soft to the knife, and has an appearance more or less greasy.

Animals with spongy feet are unfit for long journeys on hard roads. When compelled to travel thus, the feet become hot and tender, and lameness results. A mild form of laminitis, extending over a period of three or four days, often follows on this enforced travelling on a hard road, more especially in cases where the animal is 'heavy topped,' and the usual food of a highly stimulating nature. In fact, it has been the author's experience to meet with this condition several times in the case of shire stallions doing a long walk daily upon hard roads, with the weather hot and dry.

_Treatment_.--When a horse with spongy feet is shod for the first time, care must be taken to avoid excessive paring of the sole, for already the natural wear of the foot has been sufficient to keep the soft horn in a state of thinness. For the same reason hot fitting of the shoe must not be indulged in for too long a time. That common malpractice of the forge, 'opening up the heels,' must, in this case, be especially guarded against, or the excessive paring of the frog and partial removal of the bars that this operation consists in will lay the foot open to risk of contraction.

To begin with, the heels are naturally weak, and, once the bars are removed, there is nothing to prevent them rapidly caving in towards the frog. Even when carefully shod, a foot of this cla.s.s is readily p.r.o.ne to contract directly the animal is brought into the stable, and the horn commences to dry to excess. An ordinary light shoe should be used, and the nails should be light and thin. They should be driven carefully home, and the 'clinching' made as tight and secure as possible.

G. CLUB-FOOT.

_Definition_.--Under this name we indicate all cases in which the horn of the wall become straightened from above to below. It will, therefore, include all conformations varying from the so-called 'upright hoof,' in which the toe forms an angle of more than 60 degrees with the ground, to the badly 'clubbed' foot, in which the horn at the toe forms a right angle with the ground, or is even directed obliquely backwards and downwards, so that the coronary margin overhangs the solar edge of the wall.

[Ill.u.s.tration: FIG. 83.--THE CLUB-FOOT.]

_Symptoms_.--Even in its least p.r.o.nounced form the condition is apparent at a glance, the alteration in the angle formed by the hoof with the ground striking the eye at once, and the heels, as compared with the toe, appearing much too high. When the condition is slight, the wall of the toe is about twice as high as that of the heels, while in the most marked form the toe and the heels may in height be nearly equal (see Fig. 83). When congenital, but little interference with the action is noticed. Such animals, by reason of their 'stiltiness,' are unfit for the saddle, but at ordinary work will perform their duties equally well with the animal of normal-shaped feet. When acquired as the result of overwork, of contracted tendons, or other causes, however, the gait becomes stumbling and uncertain. The body-weight is transferred from the heels to the anterior parts of the foot, and the shoe shows undue signs of wear at the toe.

_Causes_.--Upright hoof is undoubtedly hereditary, and is even seen as a natural conformation in the feet of a.s.ses and mules. When hereditary in the horse, however, it is certainly a defect, and is a.s.sociated commonly with an upright limb, and a short, upright pastern (see Fig. 83).

Among other causes, we may enumerate sprains or wounds of the flexor tendons, or any disease of the limbs for a long time preventing extension of the fetlock-joint, such as sprains or injuries of the posterior ligaments of the limb, splints or ringbones so placed as to interfere with the movements of the flexor tendons, or, in the hind-limb, spavin, keeping for some months the fetlock in a state of flexion. In the very young animal the condition may be induced by an improper paring of the foot--cutting away too much at the toe, and allowing the heels to remain.

_Treatment_.--When the condition is congenital, no treatment at all is indicated. It might, in fact, be said that interference would tend rather to minimize than enhance the animal's usefulness; for, in this case, the club-shaped feet are in all probability due to faulty conformation above.

In other words, the upright hoof is in this instance but a natural result of the animal's build, with which useful interference is impossible.