’On the first occasion of operating upon and dressing the cankered foot, it is usually necessary to cast the horse, and this may have to be done at intervals for a second or even third time; but in most cases once is sufficient, subsequent dressing being usually accomplished without much difficulty, frequently even without the aid of a twitch.  After the horse has been secured, the drawing-knife is first employed; and if the frog alone is affected, it is unnecessary even to pare the sole, the removal of all frog horn not intimately adherent to its secreting surface being all that is required.  But 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 operation, is infinitesimal (canker largely destroying sensation), compared with the pain produced in the totally unnecessary process of tearing healthy horn from a highly sensitive tissue.