In every case, no matter what else the treatment, the bearing of the horn adjacent to the lesion should be removed from the shoe.

Whether practising the method of plugging the cavity or that of excision of the wall external to it, attempts to quickly obtain a new growth of horn from the coronet should be made. To further that, frequent stimulant applications should be used. Ointment of Biniodide of Mercury 1 in 8, of Cantharides 1 in 8, or the ordinary Oil of Cantharides, either will serve.

3. KERAPHYLLOCELE.

_Definition_.--By this term is indicated an enlargement forming on the inner surface of the wall. In shape and extent these enlargements vary.

Usually they are rounded and extend from the coronary cushion to the sole, sometimes only as thick as an ordinary goose-quill, at other times reaching the size of one's finger. Often they are irregular in formation and flattened from side to side.

[Ill.u.s.tration: FIG. 132.--A PORTION OF THE HORN OF THE WALL AT THE TOE REMOVED IN ORDER TO SHOW A KERAPHYLLOCELE ON ITS INNER SURFACE.]

_Causes_.--Keraphyllocele is very often a sequel to the changes occurring at the toe in laminitis. Probably, however, the most common cause is an injury upon, or a crack through, the wall. It may thus occur from excessive hammering of the foot, from violent kicking against a wall or the stable fittings, and from the injury to the coronet known as 'tread.' It may also occur as a sequel to complicated sand-crack, and to chronic corn.

That fissures in the wall are undoubtedly a cause has been placed on record by the late Professor Walley, who noticed the appearance of these h.o.r.n.y growths following upon the operation of grooving the wall.[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. iii, p. 170.]

This gentleman had a large Clydesdale horse under his care for a bad sand-crack in front of the near hind-foot, and, as the lameness was extreme, he adopted his usual method of treatment--viz., rest, fomentations, poulticing, and the making of the V-shaped section through the wall, and subsequently the application of an appropriate bar shoe to the foot, and repeated blisters to the coronet. In a short time the lameness pa.s.sed off, and the horse was put to work. A few days later the animal met with an accident, and was killed.

On examining a section of the hoof it was found that a vertical h.o.r.n.y ridge corresponding to the external fissure had been formed on the internal surface of the wall, and that a well-marked cicatrix extended upwards through the structure of the hoof at the part forming the cutigeral groove; furthermore, _a similar ingrowth had been taking place in the line of the oblique incisions made for the relief of the sand-crack_.

This case has an important bearing on the operation of grooving the wall, which operation we have several times in this work advocated for the relief of other diseases. It teaches us that the incisions should not be carried so completely through the horn as to interfere with and irritate the sensitive laminae, and so set up the chronic inflammatory condition leading to hypertrophy of the horn.

From the position on the os pedis of the indentation made in it by the keraphyllocele (see Fig. 133) it has been argued that pressure of the toe-clip is a cause of the new growth. This, we should say, cannot be a very strong factor in the causation, for, while we admit that the continual pressure of the clip, and the heavy hammering that sometimes fits it into position, is likely to set up a chronic inflammatory condition of the sensitive laminae in that region, we must still point out that the rarity of keraphyllocele, as compared with the fact that clips are on every shoe, does not allow of the argument carrying any great weight.

_Symptoms_.--Except under certain conditions this defect is difficult of detection. As a rule, lameness is not produced by it. In making that statement we are led largely by the conclusion arrived at by Professor Walley. This observer noted the fact that ingrowths of horn such as we are describing nearly always take place in false quarter, or after a sand-crack has been repaired, and that they commonly occur after the operation of grooving the wall in the manner we have just shown.

Now, we know that quite often under these circ.u.mstances the horse goes perfectly sound. Thus, while we know that in all probability keraphyllocele is in existence, we have ocular demonstration that the animal is quite unaffected by it.

In some cases, however, lameness is present. During the early stages of the growth's formation it is but slight, increasing as the keraphyllocele enlarges. Should this be the case, other symptoms present themselves.

The coronet is hot, and tender to the touch, sometimes even perceptibly swollen, and percussion over the wail is met with flinching on the part of the animal. In other cases one is led to suspect the condition by the prominence of the horn of the wall of the toe. This is distinctly ridge-like from the coronet to the ground, while on either side of it the quarters appear to have sunk to less than their normal dimensions. We believe this to be an illusion, as a ridge of any size at the toe readily gives one the impression of atrophy behind it, without this latter condition being actually present.

Should this ridge-like formation and the accompanying symptoms of pain and lameness occur after repair of a sand-crack, then keraphyllocele may, with tolerable certainty, be diagnosed. When these outward signs are wanting, however, and the true nature of our case is a matter of mere conjecture, a positive diagnosis may still be made at a later stage--that is, when the abnormal growth of horn reaches the sole. In this case either there is met with when paring the sole a small portion of horn, circular in form, distinctly harder than normal, and indenting in a semicircular fashion the front of the white line at the toe, or solution of continuity between the tumour and the edge of the sole and the os pedis takes place, and the lameness resulting from the ingress of dirt and grit thus allowed draws attention to the case.

_Pathological Anatomy_.--With the sensitive structures removed from the hoof by maceration or other means, these growths are at once apparent. They may occur in any position, but are usually seen at the toe, and they may extend from the coronary cushion to the sole, or they may occupy only the lower or the upper half of the wall. In places the tumour (or 'h.o.r.n.y pillar' as the Germans term it) is roughened by offshoots from it, and does not always exhibit the smooth surface depicted in Fig. 132. Commonly, the horn composing the new growth is hard and dense. Sometimes, however, it is soft to the knife, and is then found to be itself fistulous in character, a distinct cavity running up its centre, from which issues a black and offensive pus.

In a few cases the sensitive laminae in the immediate neighbourhood are found to be enlarged, but in the majority of cases atrophy is the condition to be observed. Not only are the sensitive structures found to be shrunken and absorbed, but the atrophy and absorption extends even to the bone itself (see Fig. 133). This latter is a result of the continued pressure of the h.o.r.n.y growth, in a well-marked case ending in a sharply-defined groove in the os pedis in which the keraphyllocele rests. The fact that the softer structures, and even the bone, thus accommodate themselves to the altered conditions is, no doubt, the reason that lameness in many of these cases is absent.

_Treatment_.--It is doubtful whether anything satisfactory can be recommended. When we have suspected this condition ourselves, it has been our practice to groove the hoof on either side of the toe, after the manner ill.u.s.trated in Fig. 120, and, at the same time, point-firing the coronet and applying a smart cantharides blister. Certainly, after this operation, lameness has often disappeared--whether, however, as a result of the treatment adopted or by reason of the structures within accommodating themselves to the condition, we would not care to say.

[Ill.u.s.tration: FIG. 133.--OS PEDIS SHOWING THE GROOVE IN IT CAUSED BY ATROPHY AND ABSORPTION INDUCED BY PRESSURE OF A KERAPHYLLOCELE.]

Other writers advocate the removal of that portion of the wall to which the tumour is attached, after the manner described on p. 182, and ill.u.s.trated in Fig. 98. This, however, should be a last resource, and should be adopted only when weighty reasons, such as excessive and otherwise incurable lameness, appear to demand it.

4. KERATOMA.

In our nomenclature the terms 'Keratoma' and 'Keraphyllocele' are both used to indicate the condition we have just described. There are some, however, who reserve the term 'Keratoma' for h.o.r.n.y tumours occurring only on the sole, and for that reason we draw special attention to the word here.

Keratoma may thus be used to describe what we have called keraphyllocele directly that growth makes its appearance at the sole, and is there able to be cut with the knife. Similar hard and condensed growths may, however, make their appearance on the sole in other positions quite removed from the white line, plainly being secreted by the villous tissue of the sensitive sole, and having no connection whatever with the sensitive laminae.

They appear as circular patches, varying in size from a shilling to a two-shilling piece. Compared with the surrounding horn, they stand out white and glistening, while in structure they are dense and hard, and offer a certain amount of resistance to the knife. They are of quite minor importance, and, beyond keeping them well pared down, need no attention.

Keratoma probably offers us the best a.n.a.logy we have to corn of the human subject.

5. THRUSH.

_Definition_.--A disease of the frog characterized by a discharge from it of a black and offensive pus, and accompanied by more or less wasting of the organ.

_Causes_.--The primary cause of this affection is doubtless the infection of the horn, and later the sensitive structures, with matter from the ground. Those factors, therefore, leading to deterioration of the horn, and so exposing it to infection, may be considered here. Such will be changes from excessive dampness to dryness, or _vice versa_; work upon hard and stony roads; prolonged standing in the acc.u.mulated wet and filth of insanitary stables, or long standing upon a bedding which, although dry, is of unsuitable material.

In this latter connection may be mentioned the harm resulting from the use of certain varieties of moss litter. This we find pointed out by J. Roalfe c.o.x, F.R.C.V.S.[A] Tenderness in the foot was first noticed, and, on examination, the horn of the sole and of the frog was found to be peculiarly softened. It afforded a yielding sensation to the finger, not unlike that which is imparted by indiarubber, and on cutting the altered horn it was almost as easily sliced as cheese-rind. The outer surface being in this way slightly pared off, the deeper substance of the horn was discoloured by a pinkish stain. The horn of the frog was in many instances found detaching from the vascular surface, which was very disposed to take on a diseased action, somewhat allied to canker, and became extremely difficult to treat.

[Footnote A: _Veterinary Journal_, vol. xvi., p. 243.]

Conditions such as these, although not const.i.tuting the disease itself, certainly lay the frog open to infection, especially if afterwards the animal is called upon to work in the mud of the streets of a large town, or to stand in a badly drained and damp stable.

A further cause of thrush is to be found in the condition of the frog, brought about by contraction of the heels (see p. 118). We have already seen that one of the most prominent factors in the causation of contraction is the removal of the frog from the ground by shoeing, with its consequent diminution in size and deterioration in quality of horn. This leads to fissures in the h.o.r.n.y covering, and favours infection of the sensitive structures beneath. Thrush is, in fact, nearly always present in the later stages of contracted foot.

By some thrush is believed to be but the commencement of canker. With this, however, we do not hold. We believe both to be due to specific causes as yet undiscovered, but that the cause of thrush is not the one operating in canker. In arriving at this conclusion we are guided by clinical evidence.

The two conditions are quite dissimilar, even in appearance, and, while one is readily amenable to treatment, the other is just as obstinately resistant.

_Symptoms_.--The symptoms of thrush are always very evident. Probably the first thing that draws one's attention to it is the stench of the puriform discharge. The foot is then picked up and the characteristic putrescent matter found to be acc.u.mulated in the median, and often in the lateral, lacunae. The organ is wasted and fissured, the horn in the depths of the lacunae softened and easily detachable, and portions of the sensitive frog often laid bare.

With a bad thrush lameness is present, the frog itself is tender to pressure, and often there is considerable heat and tenderness of the heels and the coronet immediately above. More especially is this noticeable after a journey.

It is, perhaps, more common in the hind-feet than in the fore, and more often met with in heavy draught animals than in nags. The hind-feet are, of course, more open to infection by reason of their being constantly called upon to stand in the animal discharges in the rear of stable standings, while it is a well-known fact that heavy animals have their stables kept far less clean, and their feet less a.s.siduously cared for, than do animals of a lighter type.

In a nag-horse with thrush of both fore-feet lameness becomes sometimes very great. The gait when first moved out from the stable is feeling and suggestive of corns, while progress on a road with loose stones is sometimes positively dangerous to the driver.

_Treatment_.--When this condition has arisen, as it often does, from want of counter-pressure of the frog with the ground, this pressure must be restored after the manner described when dealing with the treatment of contracted foot (see p. 125) either by the use of tip or bar shoes, or by suitable pads and stopping.

So far as direct treatment of the lesion itself is concerned, the first step is to carefully trim away all diseased horn and freely open up the lacunae in which the discharge has acc.u.mulated. Good results are then often arrived at by poulticing, afterwards followed up by suitable antiseptic dressings. With us a favourite one is the Sol. Hydrarg. Perchlor. of Tuson, used without dilution. Others use a dry dressing, and dust with Calomel, with a mixture of Sulphate of Copper, Sulphate of Zinc and Alum, or with Subacetate of Copper and Tannin.

With restoration, so far as is possible, of the frog functions, and with careful dressing, a cure is nearly always obtained.

6. CANKER.

_Definition_.--Under this unscientific, yet expressive term, is indicated a chronic diseased condition of the keratogenous membrane, commencing always at the frog, and slowly extending to the sole and wall, characterized by a loss of normal function of the horn secreting cells, and the discharge of a serous exudate in the place of normal horn.

_Causes_.--The exact cause of canker has still to be discovered. Therefore, before expressing an opinion as to what the _probable_ cause may be, we may state here that such opinion can only be based upon clinical observation.

Such being the case, we are almost duty bound to give the views of older authors before those of more modern writers.

From the ma.s.s of material ready to hand we may select the following as serving our purpose.

The earliest opinion appears to have been that canker, as the name indicates, was of a cancerous or cancroid nature. This was also believed by Hurtrel D'Arboval, who looked upon canker as carcinoma of the recticular structure of the foot. The same theory we find enunciated in the _Veterinary Journal_ so late as 1890. Although the word 'cancer' or 'carcinoma' is not there used, the author employs the terms 'Papilloma' and 'Epithelioma' with the evident intention of expressing his belief in the malignant nature of the disease.

Another early opinion was that the disease was a _spreading ulcer_, gradually extending and changing the tissues which it invaded.

A further early theory, and one which if not still believed in, has died a hard death, is the const.i.tutional theory. This was believed in by nearly all the older writers, and is mentioned so late as 1872 by the late Professor Williams. In his 'Principles and Practice of Veterinary Surgery,'

he says: 'Canker is a const.i.tutional disease due to a cachexia or habit of body, grossness of const.i.tution, and lymphatic temperament.' This, we believe, is credited to-day by some, and yet, quite 100 years before the date of the 1872 edition of Williams's work--in 1756, to be exact--we find a veterinary writer when talking of grease (a disease, by-the-by, very closely allied to canker) exclaiming against this habit of referring everything which we do not rightly understand to some ill-humour of the body. The wisdom his words contain justifies us in giving them mention here. 'It is a very foolish and absurd Notion,' he says, 'to imagine a Horse full of Humours when he happens to be troubled with the Grease. But such Shallow Reasoning will always abound while Peoples' Judgments are always superficial. Therefore, to convince such unthinking Folks, let them take a thick Stick and beat a Horse soundly upon his Legs so that they bruise them in several Places, after which they will swell, I dare say, and yet be in no danger of Greasing. Now, pray, what were these offending Humours doing before the Bruises given by the Stick?'

At the present day it is safe to a.s.sert that neither the ulcerative, the cancerous, nor the const.i.tutional theory is believed in widely, and, among the ma.s.s of contrary opinions as to the cause of this disease, we may find that even quite early many of the older writers had discarded them.