When possible, however, it is better to combine the thinning process thus described with turning out to grass. In this case the ordinary shoe is first removed, and the foot poulticed for twenty-four hours to render the horn soft. The foot is then prepared by slightly lowering the heels--leaving the frog untouched--and thinning the quarters in exactly the manner described above. After this is done, the animal is shod with an ordinary tip, a sharp cantharides blister applied to the coronet, and then turned out in a damp pasture. In this case the object of the tip is to throw the weight on to the heels and quarters. The thinned horn yields to the pressure thus applied, and a hoof with heels of a wider pattern commences to grow down from the coronet. Two to three months' rest is necessary before the animal can again he put to work.[A] [Footnote A: This is the treatment strongly advocated by A.A. Holcombe, D.V.S., Inspector, Bureau of Animal Industry, U.S.A.] _(b) Thinning the Wall in the Region of the Toe_.--This is done with the idea that the tendency of the heels to expand under pressure of the body-weight is helped by the thinned portion at the toe allowing the heels to more readily open behind. Seeing that in the case of toe sand-crack the converse is argued--that contraction of the heels readily takes place and forces the sand-crack wider open--it is doubtful whether this method is of any utility in treating contracted heels. _(c) Grooving the Wall Vertically or Horizontally, and Shoeing with a Bar Shoe_.--Marking the wall with a series of grooves, each running in a more or less vertical direction, was suggested to English veterinarians by Smith's operation for side-bones. The manner of making the grooves, and the instruments necessary, will be found fully described in Section C of Chapter X. That the method is followed by satisfactory results the undermentioned case will show: