372 SOLUTIONS OF CONTINUITY IN THE HORN. 



(c) Cracks at the Bearing Margin of the Wall 



are commonest in unshod horses, and result from excessive 

 outward strain on this part. They can generally be prevented 

 by rounding off the lower edge of the wall with a rasp before 

 turning the horse out. In shoeing, such cracks may result 

 from the use of large nails, especially when the nail holes are 

 punched too near the outer edge of the shoe. 



Every crack at the coronet may in time extend to the 

 bearing surface. To prevent such cracks in unshod horses it 

 is usually sufficient to shoe them, but in horses already shod 

 attention must be given to the position of the nail holes and 

 the use of thinner nails. The bearing surface in the neigh- 

 bourhood of the crack should be lowered in the way afterwards 

 described. To prevent the crack extending, a deep transverse 

 furrow is cut or burnt at its upper end. 



2. Transverse Cracks of the Wall 



may occur at any point ; they are generally seen at the inner 

 quarter and toe, as a result of treads from sharp or faulty 

 calkins. Pus from suppurating corns, etc., may break through 

 at the coronet, and produce the same result by interrupting, 

 for a time, the connection between the horn and coronary 

 band. Such cracks are occasionally seen at the heel, the horn 

 fibres having broken across, owing to dryness and contraction 

 of the horn. They are not of much importance, and need only 

 attract attention when they come within the region embraced 

 by the nails. 



In order to avoid disfiguring the hoof, the horn below the 

 cleft should be preserved as long as possible, the wall at this 

 point being lowered and kept clear of the shoe. If, however, 

 the piece becomes loose, it is better to remove it and fill up 

 the resulting cavity with gutta-percha or some composition. 



3. Loose Wall, Seedy Toe, etc. 



{a) When at any point in the white line the connection 

 between the wall and sole is destroyed, the resulting condition 

 is described as ' loose wall.' 



