In the first, that portion of the bearing surface of the heel of the shoe is 'dropped' about 1/8 inch from the plane of the remainder, so that the shoe at this position does not come into contact with the foot at all (see Fig. 104).

In the second case the shoe is what is termed 'set' at the heel. Here it is the plane of the _wearing_ surface of the shoe that is altered. The hinder portion of the required heel is thinned so that its lower surface does not come into contact with the ground. By this means the wall is freed from concussion and pressure. At the same time the upper surface of the shoe is in contact with the wall of the foot (see Fig. 105).

This 'setting' of the shoe is preferable to the method first described. It affords a greater protection to the foot, and does not allow of fragments of stone and flint getting in between the foot and the shoe, and so giving rise to further mischief.

The 'set' portion should be fitted full and long. It is obvious, too, that the animal should not be allowed to carry the shoe too long; otherwise, as the other portion of the shoe wears down to the level of the 'set' heel, pressure on the tender part of the foot will again result.

[Ill.u.s.tration: FIG. 104.--SHOE WITH A 'DROPPED' HEEL.]

[Ill.u.s.tration: FIG. 105.--SHOE WITH A 'SET' HEEL.]

In applying surgical shoes for corn of long standing, it must be remembered that the protection so afforded must be continued for some time. It is not sufficient to see the lesion itself disappear. In addition to that there is also, in the majority of cases, a certain amount of contraction to be overcome. This can only be done by continuing the use of a leather sole or some form of frog or bar-pad as recommended for the relief of that condition.

C. CHRONIC BRUISED SOLE.

A similar condition to that of corn may be met with in other positions on the sole. It is described by Rogerson as sand-crack of the sole[A], and is invariably met with around that portion of the sole in contact with the shoe.

[Footnote A: _Veterinarian_, vol. lxiii., p. 51.]

The animal is lame, and the shoe is removed in order to ascertain the cause. Nothing at first is noticeable except that the animal flinches when pressure is applied to the spot with the pincers, or the sole is tapped with the hammer.

On removing the sole with the knife, however, a distinct black mark is discovered, which, when followed up by careful paring, is often found to have pus at the bottom.

In this case the injury has resulted, as we have already intimated elsewhere, from causing the animal to wear for too long a time a shoe with too broad a web or insufficiently seated. Or it may have originated with the irritation set up by foreign and hard substances between the web of the shoe and the foot.

In his description of this condition Mr. Rogerson draws attention to the fact that the pus found should not be wrongly attributed to accidental p.r.i.c.king of the foot. He says:

'Considering that the cracks or splits are always found in the immediate vicinity of the nail-holes, a certain amount of discretionary skill is required in order that the lameness may be attributed to its proper cause.

This is an instance in which the presence of the veterinary surgeon is imperative, in order to prevent undue blame being attached to the shoeing-smith. Misconception in these cases might very easily arise when parties concerned are disposed to accept an unskilled opinion, sometimes resulting in danger to the proprietor of the forge, not only of losing a shoeing contract, but also of being involved in other ways which would probably prove even more disastrous.

'Horses that stand on sawdust or moss litter are sometimes found with extensive discoloration of the h.o.r.n.y sole in front of the frog. Their bedding material collects in the shoe as snow does, and forms a ma.s.s, which keeps a continued and uneven pressure upon the sole. A sound foot is not injuriously affected, but a very thin sole is, and so also is a sole which has been bruised by a picked up stone. Even a slight bruise becomes serious if pressure is allowed to remain active over the injured part. Lameness increases, serous fluid is effused between the horn and sensitive part, or even haemorrhage may take place.'[A]

[Footnote A: Hunting, _Veterinary Record_, vol. xiv., p. 593.]

_The Treatment of Chronic Bruised Sole_ offers no special difficulty.

Removal of the cause (in nearly every case incorrect bearing of the shoe) is the first consideration. That done, the lesion may be searched for and treated in the ordinary manner as described for corn. When pus is present it must, of course, be given exit, and an antiseptic solution applied to the wound. Should the sensitive structures be laid bare when allowing the pus to escape, then the wound so made should afterwards be protected with a leather sole and antiseptic stopping.

CHAPTER VIII

WOUNDS OF THE KERATOGENOUS MEMBRANE

A. NAIL-BOUND--BIND OR TIGHT-NAILING.

_Definition_.--By the term 'nail-bound' is indicated that accident occurring in the forge in which the nail of the shoe is driven too near the sensitive structures. Although involving no actual wound, it is important to consider the condition under the heading of this chapter, in order that it may be distinguished from the graver accident of a 'p.r.i.c.k.'

_Causes_.--Very largely the whole matter of causation turns on the correct fitting of the shoe. The points especially to be noticed in this connection are (1) the position of the nail-holes in the web of the shoe, (2) the 'pitch' of the nail-holes.

Regarding the position of the nails, it goes without saying that the first consideration when 'holing' the shoe should be to punch the holes opposite to sound horn. This remark applies especially to sh.e.l.ly and brittle feet, the type of feet in which tight-nailing most often occurs. The next consideration in this connection is that of punching the holes so that the nail emerges from the upper surface of the web at exactly its correct point of entrance on the bearing surface of the foot. This should be on the white line immediately where it joins the wall. From this position any marked deviation inwards ('fine-nailing,' as it is termed) is bound to give to the nail a direction dangerously near the sensitive structures.

The 'pitch' of the nail-holes should be such that the nail is guided more or less nearly to follow the line of inclination of the wall. Accordingly, the nail-holes at the toe should be 'pitched' distinctly inwards, the inward pitch lessening as the quarters are reached, until the hindermost nail-hole or two is pitched in a direction that is almost perpendicular.

Too great an inward inclination of the nail will, however, give rise to a bind.

It is probable that 'tight-nailing' results more often from fine punching of the shoe than from any fault in the pitch of the hole. Inattention to either detail, however, is apt to bring the mischief about.

Even with a correctly fitted shoe, and with a normal foot, tight-nailing may occur as a result of sheer carelessness on the part of the smith.

_Symptoms_.--Possibly the animal returns from the forge sound. It is on the following day, as a rule, that evidence of the injury is given by the animal coming out from the stable lame. In a well-marked case the foot is warmer to the hand than its fellow, and percussion over the wall will sometimes reveal the particular nail that is the cause of the trouble.

Should the shoe be removed, then the fact that the hole the nail has made is far too close to the sole often points out at once the seat of the mischief.

_Treatment_. As to whether or not the shoe should be removed is very much a matter for careful discretion on the part of the veterinary surgeon. Where the foot is sh.e.l.ly and brittle even a good smith sometimes finds himself unable to firmly attach the shoe without verging closely on causing the condition we are now describing. The author has known cases where animals with feet of this description have almost invariably returned from the forge, or rather been found the next day, with a suspicion of tenderness.

After the lapse of a day or two this has quite often disappeared, and nothing in the meantime been done with the foot. Seeing, therefore, that removal and refitting of the shoe is in this case attended with risk of breaking away portions of the brittle horn, and so rendering the foot in an even worse condition than it was before, it is policy to decline to have the shoes removed unless worse symptoms make their appearance.

In coming to this decision the veterinary surgeon must be guided by noting in the wall the points of exit of the nails. Should the nail adjoining the position already p.r.o.nounced to be tender have come out at a higher point than the others, it may be a.s.sumed that at a lower position in its course through the horn it has gone near the sensitive structures without actually penetrating the h.o.r.n.y box, and that in the course of a day or two the sensitive structures involved will accommodate themselves to the pressure thus inflicted.

If, on the other hand, symptoms of tight-nailing show themselves in an animal with good sound feet, then there is no objection to be raised against having the shoe at once removed. Should the offending nail be definitely detected, then the shoe may again be put on, and that particular nail omitted from the set.

B. PUNCTURED FOOT.

(_p.r.i.c.ked Foot_--_Nail-tread_--_Gathered Nail_.)

_Definition_.--Under this heading we propose describing wounds of the foot occurring in the sole or in the frog, and penetrating the sensitive structures beneath.

_Causes_.--These we shall consider under two headings:

1. Wounds resulting from the animal himself 'picking-up' or 'treading' on the offending object.

2. Cases of p.r.i.c.king in the forge.

Those occurring under the first heading are, of course, purely accidental.

In the majority of cases, the object picked up is a nail; but similar injury may result from the animal treading on sharp pieces of wood or iron, on pieces of umbrella wire, on pointed pieces of bones, broken-off stable-fork points, sharp pieces of flint, etc. The same accident may also occur in the forge as a result of the animal treading on the stumps of nails, from treading on an upturned shoe with the stumps of nails _in situ_, or from treading on an upturned toe-clip. It may also occur from an accidental p.r.i.c.k with the stable-fork when 'bedding up,' or from casting part of a shoe when on the road and treading on the nails, in this case left sometimes partly in and partly out of the horn.

'Serious wounds of this description are also met with in animals engaged in carting timber from plantations in which brushwood has recently been cut down. This is, of course, from treading on the stake-like points that are left close to the ground. Hunters also meet with the same cla.s.s of injury when pa.s.sing through plantations or over hedge banks, where the hedge has just been laid low or cut down.

'Agricultural horses also meet with severe wounds of this cla.s.s from treading on an upturned harrow.'[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. iv., p. 2.]

It has been remarked how strange it is that nails should so readily penetrate the comparatively hard covering of the foot. The matter, however, admits of explanation. One knows from common observation how easy it is to tilt a nail with its point upwards by exerting a pressure in a more or less slanting direction upon its head. This is exactly the form of pressure that is no doubt put upon the nail if the animal treads upon it when moving at any pace out of a walk. The foot in its movement forward tilts the nail up, and almost simultaneously puts weight upon it. The great weight of the animal is then quite sufficient to account for its ready penetration.

In purely country districts cases of punctured foot are of far less frequent occurrence than in large towns. In the latter, animals labouring in yards where a quant.i.ty of packing is done, or engaged in carting refuse containing such objects as we have mentioned, or broken pieces of earthenware or gla.s.s bottles, meet with it constantly.

For the manner of causation of those wounds to the foot occurring in the forge the reader may be referred to the matter under the heading of 'nail-bound.' As in that case so in this the nail may be wrongly directed by improper fitting of the shoe, by the 'pitch' of the hole, or by the position of the hole. The nails may also be wrongly directed as a result of faulty pointing, or by meeting with the stump of a nail that has carelessly been allowed to remain in the substance of the horn.