Treatment. - In the ordinary way the 'treatment' of side-bone is a thing but rarely mentioned. The explanation lies, of course, in the fact that side-bones are so rarely the cause of lameness. When lameness does occur with a side-bone, and we have reason to believe that the said side-bone is the cause of the lameness, it is well before talking of treatment to question ourselves thus: 'In what way does the side-bone cause lameness?' The now generally-accepted answer to that query is the explanation put forward several years ago by Colonel Fred Smith - namely, that the pain, and therefore the lameness, was due to the compression of the sensitive laminae between the ossified and enlarged cartilage and the non-yielding and often contracted wall of the quarters. That, in fact, constitutes the basis upon which Smith's operation for side-bone (that of grooving the wall of the quarters) is founded.
Before describing the operation, however, we may say that we are now able to understand that older operators who claimed success for other methods of treatment, were to a very great extent justified in so doing.
For instance, take the combined treatments of firing and blistering, and the use of a bar shoe. Here the beneficial action of the cautery and the blister may be largely problematical. The bar shoe, however, would be almost certain to give good results. Frog-pressure with the ground would be again restored, and the contraction of the heels removed. Pinching of the sensitive structures would be diminished, and the lameness cured.
Take, again, the treatment of 'unsoling.' It was barbarous, we know barbarous, because unnecessary and easily avoidable. It was practised, however, certainly very little more than two decades ago, and practised by men of standing in the profession. Without dragging the case to light again by mentioning the names of those concerned, we may mention that not many years ago a highly respected member of the profession was, at the instigation of the Royal Society for the Prevention of Cruelty to Animals, prosecuted for practising unsoling for the relief of side-bone. Practically only one other member of the profession was able to come forward and defend the operation on the score of its utility. We see now, however, that - as does Smith's operation - unsoling does permit of the greater expansion of the heels. The contraction is done away with, the pressure on the sensitive laminae again diminished, and the lameness relieved.
Not that we are attempting to defend the operation - far from it. We simply mention it as interesting, and quote this and the use of the bar shoe (with both of which methods older operators have claimed success) merely as evidence that the operation of Smith is based on a logical foundation.
When treatment is decided on, therefore, we may first advise blistering and the use of a bar shoe. After that, should the lameness continue, and should we still judge the side-bone to be the cause of it, the operation may be advised.
As we have said before, the operation consists in so grooving the wall as to allow of the quarters widening sufficiently to relieve pressure on the parts within. In one or two previous portions of this work we have considered operations involving this procedure. Before detailing the operation here, therefore, we will first describe the instruments necessary, and the most satisfactory methods of incising the horn.
To begin with, it must be remembered that all methods of hoof section have for their object the after-expansion of the horny box, and that this can only be brought about by making each groove complete from coronary margin to solar edge of the wall, and carrying it, throughout its length, deep enough to reach the commencement of the sensitive structures.
To this end, therefore, the operator must bear in mind the comparative thickness of the various parts of the wall, and must, in particular, remember the relative thinness of that portion of horn forming the outer boundary of the cutigeral groove, and accommodating the coronary cushion.
For the making of the incisions there is the special saw devised for this operation by Colonel F. Smith, A.V.D., and which we illustrate in Fig. 144. With this the wall is sawn through until the depth arrived at is equal to what is indicated by a previous examination of the thickness of the crust as viewed from the solar surface. Here Colonel Smith says: 'I strongly advise everyone to use a metal gauge (a thin piece of material) to introduce into the incision made by the saw, and run it up and down to ascertain whether the wall is properly divided throughout. The depth to which this should be done we know from the previous measurements of our gauge on the crust.'
Fig. 144. - Smith's Side-Bone Saw (Early Pattern).
Should the saw be of a pattern in which the set of its teeth makes only a narrow incision,[A] it should, while operating, be kept well oiled, and should be withdrawn every few seconds in order that the horn-dust lying in its teeth may be examined. If this is getting slightly blood-stained, we know, of course, that the sensitive structures are reached, and the incision has been carried far enough. In so judging the depth of the incision, however, care must be taken to see that the top of the coronary cushion is not injured with the saw, for if this is done the blood trickling into the depth of the incision will tinge the horn-dust, and give the false impression that the incision is sufficiently deep.
[Footnote A: That is Smith's older pattern. The newer pattern (Fig. 145) has the teeth so set as to make an incision wide enough to be looked into. In this case the depth arrived at is to be judged by the appearance of the bottom of the incision.]
If the operator has had no previous experience of the use of the saw in this operation, he must also be careful to avoid placing too great a pressure on the teeth of its lower third. This is done by keeping the hand too greatly depressed. Again, this leads to wounding of the sensitive structures (this time at the lower end of the incision), and again the operator is confused by the blood thus allowed to run into the groove.
The only portion of horn difficult to operate on is that immediately under the coronet. This is best severed with a succession of downward movements, and is easier performed with Smith's later pattern of side-bone saw (Fig. 145) in which the set of the foremost teeth is reversed.
Fig. 145. - Smith's Side-Bone Saw (Improved Pattern).