e to say, in this, a
well-marked case, the cause was altogether obscure. We quote the case at
the end of this section.

[Illustration: FIG. 165.--DIAGRAM SHOWING THE COURSE TAKEN BY THE NEEDLE
WHEN SETONING THE FROG. This is shown by the dotted curved line _a, b_.
1, The navicular bone; 2, the plantar cushion; 3, the os pedis; 4, the
perforans tendon.]

A partial dislocation of this articulation is the condition met with in
'Buttress Foot.' In this case the fracture of the pyramidal process, and
the consequent lengthening of the tendon of the extensor pedis, allows the
os coronae to occupy upon the articulatory surface of the os pedis a more
backward position than normally it should.

It is quite probable, too, that slight lesions of the other restraining
ligaments and tendons of the articulation may bring about a similar though
less marked condition. We may be quite sure of this--that whenever such
lesions (as, for example, sprain and partial rupture of the lateral
ligaments) do occur, and the normal position of the opposing bones is
changed, if only slightly, that great pain and excessive lameness must be
the result, and this with but little to show in the foot. Many of our cases
of obscure foot lameness might, if capable of demonstration, turn out to be
cases of sprain and partial dislocation of the pedal articulation.

_Recorded Case_.--'The animal, a trooper of the 8th Hussars, was found on
the morning of April 17 unable to bear any weight on the limb (the
near hind). Cause not known--the heel-rope I thought at first; but on
investigation I found the heel-rope had been on the other leg.

_Diagnosis_.--Dislocation of the left os coronae from the articulating
surface of the os pedis in a backward direction.

'Every devisable means were unsuccessful in reducing the limb to its
natural position. The horse was thrown, and a strong rope, with four men
pulling at it, was fastened round the hoof, whilst I put my knee to the
back of the pastern, using all possible force, with one hand to the foot
and the other to the fetlock, but all to no purpose. Next day other means
were tried. First by throwing the horse and placing him on his belly, with
the fore-legs stretched out forwards, and the hind-legs backwards. This I
did so as to get the injured limb placed as nearly flat on the ground as
possible, with its anterior aspect downwards. Then a very heavy man, with
his boots off, was made to jump on the back of the pastern,