Diseases of the Horse's Foot Part 16

Where the upright hoof is a consequence of excessive paring of the toe, or insufficient removal of the heels, the condition may be remedied by directing attention to those particulars, and preventing their continuance.

At the same time, a greater obliquity of the limb axis may be given by the use of a suitable shoe. The shoe indicated is a short one, with thin heels and a thick toe. In some cases the abnormality may be remedied by the use of a tip. Whatever method is adopted, care must be taken not to attempt too positive a change in the direction of the limb at one operation. The process must be gradual.

In cases where the abnormality has been brought about by wounds to the flexor tendons, the alteration in the direction of the limb is often so great as to produce 'knuckling over' of the fetlock. This, to a very great extent, may be remedied by the use of a shoe with calkins and an extended toe-piece (see Fig. 84).

[Ill.u.s.tration: FIG. 84.--THE SHOE WITH EXTENDED TOE-PIECE AND HIGH CALKINS.]

With this shoe a certain amount of forced exercise is advisable, and at intervals of about two weeks the calkins should be somewhat lowered, until the heels are brought as close to the ground as is possible. In giving directions for this shoe to be made the veterinary surgeon must, when referring to the length of the toe-piece, be guided entirely by the condition of the case. Ordinarily, a suitable length is from 3 to 4 inches.

It is necessary also to warn the owner that, by reason of the length projecting, the shoe is liable to be torn off.

Should the 'knuckling over' have become complicated by bony deposits round the seat of the original injury, then a favourable modification of the condition is not so likely to result.

The benefit to be derived from the shoe with an extended toe-piece in a case of excessive knuckling is admirably shown in a brief report of a case, under the t.i.tle of 'Hooked Foot,' in vol. xiv. of the _Veterinary Record_, p. 716:

'An eighteen months' old filly showed a deformity of the third phalanx, resulting in her walking with the front face of the hoof on the ground. The flexors were apparently all right, and the bending back seemed to be due to contraction of the ligaments of the joint and the sheath of the perforans.

'On the ground of absence of contraction of the flexors, or atrophy and paralysis of the extensors, the surgeon considered the lesion curable by simple orthopaedic measures. By means of an elongated toe-piece to the shoe and calkins, which were shortened every fifteen days, the filly was completely cured in seventy days.'

H. THE CROOKED FOOT.

(_a_) THE FOOT WITH UNEQUAL SIDES.

_Definition_.--The foot thus affected has one side of the wall higher than the other.

_Symptoms_.--This deformity is the better recognised when the foot on the floor is viewed from behind. In addition to the difference between the height of the inner and outer heel is seen at once a deviation in the normal direction of the horn. That of the higher side is distinctly more upright than that of the lower, and runs from above downwards and inwards towards the axis of the foot, while the horn of the lower side maintains its normal direction of downwards and outwards.

From what we have said before on contracted foot, this bending in of the wall of the upright side will at once be recognised as a form of contraction. It is, in fact, contraction confined to one-half of the foot only, and, as a result, the upright side of the crooked foot is p.r.o.ne to the troubles arising from that condition. Corns are frequent, and atrophy of that half of the frog on the affected side supervenes. With the inflammatory changes accompanying these conditions we find the horn of the affected side deteriorating in quality. It becomes dry and brittle, and extremely liable to sand-crack. At the same time, thrush of the contracted frog begins to make its appearance.

_Causes_.--More often than not this condition is a result of the conformation of the limb. According as the build above inclines the animal to 'turned in' or 'turned out' toes, so shall we have feet with a wall crooked inwards or crooked outwards; and it may be mentioned here that the evil results inflicted on the foot by ill-shaped limbs above will make themselves the more readily noticed when the animal comes to be shod for any length of time. So long as a natural wear of the foot is allowed, so long does it accommodate itself to the form of limb above. So soon, however, as the shoe is applied, and a more or less equal (and in this case harmful) wear by that means insisted on, so soon does this abnormal change in the height and direction of the horn fibres begin to make itself seen.

While arising in the majority of instances from faulty conformation of the limb, crooked feet may also be brought about by bad shoeing, or by unequal paring of the foot, and, in a few cases, from unequal wear of the foot in a state of nature.

_Treatment_.--Although it may be taken as a rule that lowering of the higher wall, even if persisted in at every shoeing, will do nothing towards remedying the primary cause (viz., the evil conformation of the limb), yet it will serve to keep the condition within reasonable limits. In this case, while removing so much of the wall as is deemed necessary, care must be taken to leave uncut the sole and the bar. Leaving these intact gives us two natural and very potent protections against the contraction already mentioned as impending.

Where, by reason of the thinness of the horn or other causes, sufficient paring to equalize the tread cannot be practised, then the same end may be arrived at by the use of special shoes. That branch of the shoe applied to the half of the foot with the lower wall should be thickened from above downwards. Or, on the same branch, may be turned up a calkin of sufficient height for the purpose. Of the two methods the first is preferable.

In any case, whether depending upon paring, or upon the use of a special shoe, the animal should be sent to the forge quite often, for it is only by a well-directed, and therefore constant, application of the principles here laid down that improvement may be brought about.

When marked contraction of one-half of the foot is present, it will be best treated with the expanding shoe of Hartmann, already described in the section of this chapter dealing with contracted heels (see Fig. 76).

(_b_) THE CURVED HOOF.

_Definition_.--The hoof with the wall of one side convex, and that of the opposite side concave. Fig. 85, showing the foot in section from side to side, gives an exact idea of this malformation.

_Causes_.--As was the case with the condition previously described, this abnormality finds its primary cause in an unequal distribution of weight due to vice of conformation in the limb above, causing one side of the hoof to be higher than the other. As a result of this, the wall that is inordinately increasing in height commences to bulge outwardly (Fig. 85, _a_), while the opposite (Fig. 85, _b_) becomes concave.

The same state of affairs may be occasioned in the forge by leaving one side of the foot too high, and subjecting the other to excessive paring for several consecutive shoeings.

_Treatment_.--In the main this condition may be regarded as a long-standing and aggravated form of the foot with unequal sides. We may say at once, therefore, that it is not so easily remedied as that simpler defect; that, although identical principles will be followed in its treatment, cure must be a matter of some considerable time.

[Ill.u.s.tration: FIG. 85.--SECTION THROUGH A CROOKED FOOT. _a_, The higher and convex side of the wall; _b_, the lower and concave side of the wall]

Again, we must look to successive parings of the wall of the higher side to bring about a gradual return to the normal. At the same time, the tendency to contraction of that side is counteracted by shoeing wide, and, if necessary, giving to the upper surface of that branch of the shoe what we have termed elsewhere a 'reversed seating'--viz., an incline of its upper surface from within outwards.

CHAPTER VII

DISEASES ARISING FROM FAULTY CONFORMATION

A. SAND-CRACK.

_Definition_.--A solution of continuity of the horn of the foot, occurring usually in the wall, and following the direction of the horn fibres.

_Cla.s.sification_.--It is usual to cla.s.sify sand-cracks according to--

_(a) Their Position_.--_Toe-crack_ when occurring in the middle line of the horn of the toe, and _quarter-crack_ when occurring in the horn of the quarters.

Sand-crack of the frog and sand-crack of the sole may also each be met with. They are, however, of rare occurrence, and are seldom serious enough to merit special attention.

The toe-crack is met with more often in the hind-foot than in the fore, while the quarter-crack more often than not makes its appearance in the fore-foot, and is there, as a rule, confined to the inner side. The reasons for these positions being so affected we shall deal with when treating of the causes of sand-crack in general. It is interesting to note that the portions of wall known as inside and outside toe are seldom affected.

_(b) Their Length_.--_Complete_ when they extend from the coronary margin of the wall to its wearing edge; _Incomplete_ when not so extensive.

_(c) Their Severity_.--_Simple_ when they occur in the horn only, and do not implicate the sensitive structures beneath; _Complicated_ when deep enough to allow of laceration and subsequent inflammation of the keratogenous membrane. Such complications may vary from a simple inflammation set up by laceration and irritation of the sensitive structures by particles of dirt and grit that have gained entrance through the crack, to other and more serious changes in the shape of the formation of pus, haemorrhage from the laminal vessels, caries of the os pedis, or the development of a tumour-like growth of horn on the inner surface of the wall known as a keraphyllocele.

_(d) Their Duration_.--_Recent_ when newly formed; _old_ when of long standing.

_(e) Their Starting-point_.--This last distinction we make ourselves, and, referring to cracks of the wall, term them _high_ when commencing from the coronary margin, _low_ when starting from the bearing surface.

_Causes_.--We have already cla.s.sified sand-crack as a disease arising from faulty conformation. Thus, in just so far as a predisposing build of body may be handed down from parent to offspring, we may regard sand-crack as hereditary. If we do so, however, we must afterwards make up our minds to sharply distinguish between the sand-crack plainly brought about by accidental cause, and that occurring as a result of hereditary evil conformation.

With regard to the latter, we need hardly say that feet with abnormally brittle horn are extremely liable. But with this, as with many other affections of the feet, we shall find it necessary to consider several causes acting in cooperation. In this case, for instance, given the brittle horn, it becomes necessary to further look for exciting causes of its fracture.

We will take conformation first. In the animal with turned-out toes a more than fair share of the body-weight is imposed on the horn of the inner quarter. Here, then, three causes exert their influence together: The horn is brittle; the wall of the inner quarter is thinner than that of the outer; additional weight is imposed upon it. Fracture results.

Take, again, the vice of contracted heels. Here, in the first place, we have a variety of causes tending to bring about the contraction. With the contraction, and its consequent pressure upon the sensitive structures in the region of the quarters and the frog, has arisen a low type of inflammation. The horn of the part has become dry and brittle. The exciting cause of its fracture is found in an excessive day's work upon a hard, dry road, with, perhaps, a suddenly-imposed improper distribution of weight, due to treading upon a loose stone, or a succession of such evil transfers of weight due to travelling upon a road that is rough in its whole extent.

In their turn, too, such defects of the feet as we have mentioned in the last chapter--as, for example, the foot with the pumiced horn, the foot with abnormally upright heels, or that which is upright on one side only, or crooked--each offers a condition which is predisposing to the formation of a sand-crack. In each case it wants but the uneven distribution of the body-weight, which, as a matter of fact, some of these conditions themselves give, to bring about a fracture.

Apart from the predisposition conferred by conformation, must be remembered the simpler predisposing causes leading to brittleness of the hoof. We refer to the after-effects of poulticing, the moving from pasture to stable, the emigration from a damp to a dry climate, or the alternate changes from damp to dry in a temperate region. Each may have a deteriorating influence upon the horn, rendering it liable to the condition we are describing. Excessive dampness alone, especially when the animal is called upon to labour at the drawing of heavy loads upon a rough road, is not infrequently a cause. In this case the wet, together with the constant friction of the sharp materials of which the road is made, serves to destroy the varnish-like periople. The wet gains access to the inner structures of the wall, the agglutination of the horn fibres is weakened, and fissures begin to appear.

Other causes of sand-crack are purely accidental. An animal at fast work over-reaches. The secretion of horn at the injured coronet is interfered with, a diminished supply at an isolated spot being the result. From this point grows down a fissure in the wall.

An injury of the same character may also be sustained in various other ways--treads from other animals when working in pairs, accidental wounding with the stable-fork, blows of any kind, or a self-inflicted tread with the calkin of an opposite foot--each with the same result.

So far as causation is concerned, toe-crack stands in a cla.s.s almost by itself. It is met with nearly always in a heavy animal in the hind-foot, and is directly attributable to the force exerted in starting a heavy load.