These sections will expose to view the cavity formed by the pouring out of the exudate, and its full extent may be noticed by examining the sections alternately.  Taking the horizontal section first, it will be seen that the hollow space extends wholly round the toe, and as far back as the commencement of the quarters.  In the latter position one is able to observe laminae still in their normal positions and condition.  At the toe, however, the horny and secretive laminae are widely separated, and the space between them filled with a yellow, semi-solid material, the remains of the inflammatory exudate and new horn secreted by the keratogenous membrane.  The laminae, both horny and sensitive, are greatly enlarged.  This is a hypertrophy, resulting from the continued effects of the inflammation, and leads in time to the formation of laminae quite three or four times their normal size.  It is this hypertrophy of the laminae and the pressure of the exudate that causes the bulging and increased growth of the horn at the toe (see Fig. 125), and contributes towards the oval formation of the foot we have mentioned before.

[Illustration:  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 papillae 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.