FIG. 125.—LONGITUDINAL SECTION OF A FOOT WITH LAMINITIS OF SEVERAL YEARS' DURATION.
In the longitudinal section the first thing noticeable is the change in position of the bones, more especially in that of the os pedis. The circumstances we have mentioned before—pressure of the exudate upon it in front and tension of the perforans on it behind—have caused it to assume a more upright position than is normal, so much so that in a bad case the front of the bone becomes quite vertical. This vicious direction the other bones of the digit follow (see Fig. 125).
Consequent upon the displacement of the bone, the plantar cushion, by reason of the continued pressure thus put upon it, becomes atrophied, while its hinder half is, as it were, squeezed into taking up a position more posterior and higher in the digit than normally it should. The horn-secreting papillæ covering its inferior face thus become directed backwards sooner than downwards, in which way we account in some measure for the noticeable increase of horn at the heels.
Treatment.—Chronic laminitis is incurable. Treatment must therefore be directed towards the palliation of such conditions as are present, with the object of rendering the the animal better able to perform work. When perforation of the sole has occurred, with the attendant formation of pus and necrosis of the os pedis, it is doubtful whether treatment of any kind is advisable. There are on record cases of this description, where careful curetting of the exposed and necrotic portions and the after application of antiseptic dressings, held in position by a plate shoe or a leather sole, has been followed by good results, and the animal restored for a time to labour. In our opinion, however, early slaughter is the most economical course to adopt, and certainly the wisest advice to give to the ordinary client.
When perforation of the sole is absent, and when serious alteration in the shape of the horny box has not occurred, then the most simple treatment is to put the animal straight away to slow work, with the feet protected by suitable shoes.
Here, again, the most useful shoe is the Rocker Bar (Fig. 119). The broad web and deep seating gives ample protection to the convex sole, and with the ease in distributing his weight that this shoe affords the animal is able to perform slow work on soft lands with some degree of comfort.
Should the growth of the horn at the toe and at the heels be unduly excessive, then our attention may be directed towards reducing it to some approach to the normal. This is accomplished by removing with the rasp and the knife those portions indicated by the dotted lines in Fig. 127. Here it will be seen that the bulk of the horn removed is that protruding at the toe. After this the animal should again be suitably shod. In this connection it should be noted that the fact of the animal walking largely on the heels tends to a forward displacement of the shoe. This must be prevented by providing each heel of the shoe with a clip, after the manner shown in Fig. 128; or, in the case of a bar shoe, supplying it with a clip at the centre of the bar.