370 SOLUTIONS OF CONTINUITY IN THE HORN. 



special clips. The choice of these must be determined by the 

 position and character of the crack. Bar shoes are only resorted 

 to when the bearing surface of the wall is defective. 



2. Quarter and heel cracks are best treated by the use of 

 bar shoes. Before nailing on, the portion of the wall below 

 and behind the crack should be lowered so as to relieve it of 

 weight. The exact area from which to remove horn can be 

 judged as follows. The crack is prolonged in imagination in 

 the same direction as the horn hbres until it reaches the 

 bearing surface. From the upper end of the crack an im- 

 aginary vertical line is dropped to the bearing surface of the 

 hoof. The portion comprised between these two lines is then 

 lowered sufficiently to prevent any pressure on that part 

 until the next time of shoeing (fig. 852). Another, and per- 

 haps preferable, method is to seat out the shoe at the points 

 indicated, leaving the wall untouched. 



The same rule applies to cracks at the heel, even when 

 the imaginary vertical line falls behind the bearing surface. 

 Stoppings are of value because they convey a portion of the 

 body-weight to the sole and frog, lead to expansion of the hoof, 

 and diminish concussion during movement, all of which tend 

 to prevent the new horn from cracking. 



When the crack is widely open and the frog small, or when 

 the hoof is contracted, a shoe with bar-clips may be employed. 



If the edges of the crack are irregular or overlapping, all 

 projecting parts should be removed. To assist the growth of 

 sound wall and diminish the tendency to fresh fissures, the 

 upper portions of the wall near the crack should be thinned, 

 the hoof kept moist, and a sandcrack boot or tape applied. 

 French clips are not advisable in cracks of the quarter, and 

 are distinctly injurious in cracks of the heel. To prevent 

 the fissure extending further, a furrow may be burnt or cut 

 at its extreme end, and at right angles to its general direction. 

 The furrow is made at the lower end of cracks starting from 

 the coronet, and at the upper end of those starting from the 

 bearing margin of the wall. 



Blisters of cantharides or biniodide of mercury are some- 

 times applied to the coronet to stimulate the growth of horn. 

 The wall secreted is found to be thicker than before. Animals 

 suffering from sandcrack often recover without treatment if 



