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.

Fig. 132.   A Portion Of The Horn Of The Wall At The Toe Removed In Order To Show A Keraphyllocele On Its Inner Surface

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 horny 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 passed 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 horny 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 circumstances 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 'horny 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 horny 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 illustrated 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.

Fig. 133.   Os Pedis Showing The Groove In It Caused By Atrophy And Absorption Induced By Pressure Of A Keraphyllocele

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 illustrated 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.