(f) By turning out to Grass.—Where the expense of keep is no object, a return of contracted feet to the normal may be brought about by removing the shoes and turning the animal out to pasture, thus giving the feet the advantages to be derived from a more or less continuous operation of the normal movements of expansion and contraction. In this case the treatment must extend from three to four, or possibly six months.
2. By the Use of Some Form of Expansion Shoe.
FIG. 73.—SMITH'S EXPANSION SHOE SEEN FROM ITS GROUND SURFACE AND FROM THE SIDE. a, The screw, with a fine-cut thread; b, nut which travels along it; c, a hollow thimble into which the screw passes at one end, the other being cut out V-shaped to catch into a slot (d) on the shoe; e, e, the grip[A] for the bars, the length and direction of which depend upon the shape of the foot; f, f, the counter-sunk rivets forming the hinge (f'); g, the counter-sunk rivet of the expanding piece.
[Footnote A: The inventor of this shoe uses the word 'grip' to denote what, in describing other expansion shoes, we term the 'clip' (H.C.R.).]
(a) Smith's.—For many years past continental writers have been practising this method. So far as we know, however, Lieutenant-Colonel Fred Smith was the first English veterinarian to use a shoe of his own devising, and to report on its effects. This shoe we will, therefore, give first mention.
The above figure, with its accompanying letterpress, sufficiently explains the nature of the shoe. In fitting the shoe, care must be taken to have the hinges (f, f) far enough back, or the shoe will have a tendency to spring at the heels, and the grips (e, e), which catch on the bars, will have a difficulty in biting. This trouble will be avoided by having the hinges about 1-1/2 to 2 inches from the heels.
After the shoe has been firmly nailed to the foot, the travelling nut b is driven forward on the screw a so as to cause the grips to just catch on the inside of the bars of the foot. According to the inventor, the amount of pressure to be exerted must be learned by experience, and he says:
'I screw up very gradually until I see the cleft of the frog just beginning to open. I now trot the horse up, and if he goes sound it is certain that the pressure I have exercised will not give rise to trouble. The animal is sent to work to assist in the expansion of the foot. On examining the shoe next day, the grip is found to be quite loose, the foot has enlarged, and the nut is turned once more until the grip on the bars is tightened, the horse being again trotted to ascertain that no injurious pressure is exerted.