Those who advocate it do so for the reason that it relieves pressure on the injured parts.

That it does so directly from below cannot be denied; but that it also favours contraction and compression from side to side is equally certain.

A moderate paring may, however, be indulged in, say, to about one-half the estimated thickness of the sole.  Softening of the horn and consequent lessening of pressure may then be brought about by the use of oil, oil and glycerine, tincture of creasote, or by poulticing.

In the case of a moist corn the paring should be stopped immediately the true nature of the injury has made itself apparent.  Warm poultices or hot baths should then be used in order to soften the surrounding parts, lessen the pressure, and ease the pain.  After a day or two day’s poulticing, should pain still continue with any symptom of severity, the formation of pus may be expected, and it is then time for the paring to be carried further, until the question ‘pus or no pus?’ is definitely settled.

Should the moisture be due simply to the presence of the inflammatory exudate, then poulticing alone will have the desired effect, and the pain will be lessened.  With the decrease in pain the poulticing may be discontinued, and the horn over the seat of the injury dressed with some antiseptic and hardening solution.  Sulphate of zinc, a mixture of sulphate of zinc and lead acetate, sulphate of copper, or the mixture known as Villate’s solution,[A] may either of them be used.  Suitably shod, and with a leather sole for preference, the animal may then again be put to work.

[Footnote A:  The composition of the escharotic liquid bearing his name was published by M. Villate in 1829 as under: 

Subacetate of lead liquid    ...         ...         ...    128 grammes. 
Sulphate of zinc     [=a=a]  ...         ...         ...     64 grammes. 
Sulphate of copper,  [=a=a]  ...         ...         ...     64 grammes. 
Acetic acid   ...            ...         ...         ...      1/2 litre.

Dissolve the salts in the acid, add little by little the subacetate of lead, and well shake the mixture.]

When dealing with suppurating corn, then, a considerable paring away of the horn of the sole becomes a matter of necessity.  The freest possible exit should be given to the pus, and this even when an opening has already occurred at the coronet.  Unless this is done, and done promptly, the putrescent matter still contained within the hoof will make further inroads upon the soft structures therein, and later upon the ligaments, and even bone itself.

Having given drainage to the lesion by the dependent orifice in the sole, poulticing should again be resorted to and maintained for at least three or four days.  The poulticing may then be discontinued, and the openings in the sole injected with a weak solution of Tuson’s spts. hydrarg. perchlor., a 1 in 20 solution of carbolic acid, a solution of copper sulphate, with Villate’s solution, or with any other combined antiseptic and astringent.  The success of the treatment is soon seen in the cessation of pain and in the decreased amount of discharge from the opening in the sole.