’Should subjacent healthy structures be destroyed during the process, that is shown by the production of a raw sore, or of a sore to which a “sit-fast,” coextensive to the injury, is firmly attached.  This seriously retards recovery.  The secreting surface having been destroyed, no new horn can be produced directly from the part, and a new secreting surface and new horn have now to grow inwards from the surrounding undestroyed tissue, and that is a slow process.  At the same time, on the principle of choosing the least of two evils, practical experience teaches that it is better to produce a small sore or a “sit-fast” than to leave a part of the canker undetected; but, on the other hand, it is better to leave a small part of canker undetected, which can be recognised and removed at the next examination, than to cause a large slough.  The object of the skilful surgeon is, naturally, to avoid both extremes; and if trouble be taken to carry out the procedure described, there need be no fear of the result.’[A]

[Footnote A:  Journal of Comparative Pathology and Therapeutics, vol. iv., p. 24.]

Treated in this way, the horse with cankered feet may be usually kept at work during the whole time that treatment is carried out, and a cure is obtainable in periods varying from six weeks to six or even twelve months.

The same essentials in treatment—­namely, removal of diseased horn, antiseptic dressings, and pressure—­are insisted on by other writers.  Bermbach,[A] in 1888, treats canker as follows:  The horse having been cast, the undermined hoof-horn is removed with the knife, and the hypertrophied sensitive structures, if necessary, reduced in the same manner.  The chief difficulty in removing the latter is experienced in the lateral lacunae of the frog, where it is most conveniently scraped away with a spoon or sharp curette.  Professors Hoffmann and Imminger also operate in the same way, applying an Esmarch’s haemostatic bandage, and using the knife and curette freely.[B]

[Footnote A:  Ibid., vol. ii., p. 68.]

[Footnote B:  Veterinary Journal, vol. xxxv., p. 433.]

Haemorrhage is afterwards arrested, and a dressing of perchloride of mercury (a solution, 1/2 per cent., in equal parts of alcohol and water) applied.  The after-dressings succeeding best are those of slightly caustic and astringent agents, preferably in the form of a powder, and held in position by carbol-jute pads and linen bandages applied with a certain amount of pressure.

The same author draws attention to the fact that caustic agents such as nitrate of lead, chloride of zinc, etc., act too powerfully if the bleeding has been arrested and the wound disinfected.  They then form a thick crust, under which profuse suppuration takes place.  The same agents are likewise contra-indicated when haemorrhage is still present.  In this latter case they combine with the blood to form metallic albuminates, which lie as an impenetrable layer on the surface of the wound, and so hinder the action of drugs on the tissue below.