ut if both sole and frog be involved, the whole of the
sound horn should be first thinned until it springs under the thumb,
and then, using a sharp knife, every particle of diseased horn must be
carefully removed from both sole and frog, a process much more easily, and
with far greater certainty, secured by the previous thinning of the horn.

'The removal of diseased horn should always commence at the most dependent
part of the foot, so that any haemorrhage produced may be below the parts
still to be operated on, a matter of considerable moment for effective
treatment. But with due care there will be little haemorrhage, as, except in
the initial stage, there is no real union between the diseased horn and the
diseased vascular secreting surface.

'After all apparently diseased horn has been removed by the knife, any
still remaining should be at once destroyed by the actual cautery, by
which it can be identified. All the diseased secreting surface should be
_carefully scraped with a thin hot iron_,[A] fungoid growths excised and
cauterized, and, indeed, every particle of cankered tissue should, if
possible, be eradicated. In securing this more reliance can be placed on
the actual cautery than on any other, whether liquid or solid: it is more
under control in application, more decisive in effect, and its results can
be anticipated with a far greater certainty. Moreover, its aid in diagnosis
is of immense value; applied to the thinned horn or secreting surface it
unmistakably demonstrates the presence or absence of canker. Healthy tissue
chars black; cankered tissue, on the contrary, bubbles up white under the
hot iron, and presents an appearance not unlike roasted cheese.

'Although this test is certain for horn thinned to the quick, it is not to
be relied upon with thick horn, the outside of which may be practically
healthy and char black, while its underlying surface may be cankered. With
this exception the test is an infallible one, as by it the demarcation
between cankered and healthy tissue can be clearly traced, and as a result
we can with equal confidence radically _remove_[A] all cankered tissue, and
conserve all healthy. As the object of that abominably cruel and barbarous
operation of stripping the sole is the exposure of all canker, and as this
can be done with equal certainty with the aid of the hot iron, there can be
no necessity for performing it. The pain of cauterizing cankered tissue,
which is a necessary