ately. 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,