, but occurs also in the fore.

_Pathological Anatomy_.--When occurring without fracture, the first
observable change is a thinning of the articular cartilage of the pyramidal
process, through which the bone beneath appears abnormally white. Later
the thinning of the cartilage progresses until at last it becomes entirely
obliterated. This destruction of the cartilage commences first at the
highest point of the articular surface of the pyramid, and gradually
reaches further backward into the joint. While this is taking place the new
bone is being formed on the front of the os pedis, below and around the
process, until, as we have already seen, an exostosis is formed, large
enough to be noticeable at the coronet. This, of course, partly implicates
the joint and the points of the insertion of the extensor tendon.

Finally, fracture may, or may not, take place. When it does, the exostosis
is larger, and the general deformity of the hoof greater.

_Treatment_.--Ordinary treatment, such as point or line firing, repeated
blisters, or hoof section, each of which we have tried, appears to be
utterly useless. So far as we have been able to gather from the writings of
other practitioners, however, neurectomy returns the animal for a time to
usefulness. If the fore-limb is the seat of trouble, either plantar or
median neurectomy may be practised; if the hind, then the best results are
obtained by section of the posterior tibial.

_Reported Cases_.--1. This animal, a mare, had been rested for lameness
behind for two or three weeks, and then sent out to work, going sound. This
was repeated several times, and each time the coachman reported, "Goes very
lame behind after she has been at work about fifteen to twenty minutes."
She always pulled out sound when I saw her in a halter on the following
day, so I had her ridden, and after about seven or eight minutes she began
to go lame in a hind-limb. Her lameness got rapidly worse as she was being
ridden, and within a quarter of mile of her first showing lameness, she
dropped and carried the lame foot in a way that suggested a badly fractured
pastern. There was no recognisable disease in the limb to account for this
lameness.

'I divided the posterior tibial nerve, and she went back to work moving
sound, and continued to work sound up to her death from one of the
regularly fatal bowel lesions twist or rupture.

'She worked nearly two years after unnerving, and developed the usual
thick