3. By Operations on the Horn of the Wall.
(a) Thinning the Wall in the Region of the Quarters. - This is best done by means of an ordinary farrier's rasp. The thinning should lessen gradually from the heel for 2-1/2 to 3 inches in a forward direction. That portion of the wall next to the coronary border, about 1/2 inch in breadth, should not be touched. At this point the thinning should commence, should be at its greatest, and lessen gradually downwards until at the inferior margin of the wall the normal thickness of horn is left. The animal is then shod with a bar shoe and the hoof bound with a bandage soaked in a mixture of tar and grease, in order to keep the thinned portion of the wall from cracking. In this condition the animal may remain at light labour.
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 (Diseases Of The Lateral Cartilages. A. Wounds Of The Cartilages).
That the method is followed by satisfactory results the undermentioned case will show:
'A mare, which I have had in my possession since she was a foal, has always had contracted feet, which were also unnaturally small.... Lately the mare has been going very "short," and at length her action was quite crippled. At times she was decidedly lame on the off fore-foot. At no time have I been able to detect any sign of structural disease. I thereupon concluded that the lameness was due to mechanical pressure on the sensitive structures, and I determined to try the effects of the above treatment. As this was my first experience of the process, I was careful to carry it out in all its details, as described by Professor Smith. After the bar shoes had been put on, the mare was very lame. I allowed her two days' rest, then commenced regular walking exercise, and she daily improved. After fourteen days there was no lameness, but still short action. I thereupon gave the mare another week's walking exercise, at the expiration of which I drove her a short turn of five miles, which she did quite well, and free from lameness. For three months I kept the saw-cuts open to the coronet, and continued the bar shoes, keeping the mare at exercise, and giving her occasionally a drive. She never liked the bar shoes, and I was glad when I could discontinue them, which I did in the fourth month. When shod with the usual shoes the complete success of the treatment was shown. I have now had her going with the ordinary shoes for the past two or three months, and the improvement in the shape of the feet is very marked; there is no lameness; the mare is free in movement, fast, and spirited, whereas previously she was quite the reverse, and almost unfit to drive.'[A]
[Footnote A: W.S. Adams, M.R.C.V.S., Veterinary Journal, vol. xxx., p. 19.]
This method, though but recently introduced to the English veterinary surgeon, is by no means new. According to Zundel, it was recently made known on the Continent by Weber, but was previously known and mentioned by Lagueriniere, Brognier, and Hurtrel d'Arboval.
When the grooving is in a horizontal direction, a single incision is sufficient. This is made 3/4 inch below the coronary margin of the wall, and parallel with it, extending from the point of the heel for 2 or 3 inches in a forward direction. As in the previous method, a bar shoe is applied, and the animal daily exercised. Thus separated from the fixed and contracted portion of the wall below, the more elastic coronet under pressure of the body-weight commences to bulge. The bulging is of such an extent as to cause the new growing hoof from the top to considerably overhang the contracted portion below, and cure of the condition results from the newly-expanded wall above growing down in a normal direction.
This consideration of contracted heels may be concluded by drawing attention to the advisability of always maintaining the horn of the wall in as soft and supple a condition as is natural by the application of suitable hoof dressings.
A useful one for the purpose is that made with lard, to which has been added a small quantity of wax or turpentine.
Especially should a dressing like this be used when the hoof is inclined to be hard and brittle, and where tendency to contraction has already been noticed.
The application of a hoof ointment is also particularly indicated where the foot is much exposed to dampness, where the animal is compelled to stand for long periods upon a dry bedding, or where the bedding is of a substance calculated to have a deleterious effect upon the horn.
This, in conjunction with correct shoeing, will probably serve to avoid the necessity for more drastic measures at a later time.