352 DADD'S VETERINARY MEDICINE AND SURGERY. 



Sand-crack. 



" The name of sand-crack seems of questionable application. It 

 J3, evidently, a compound of the word sand and crack, as though 

 it denoted a crack with sand in it, or a crack occurring in a sandy 

 country, or in a dry, sandy season, which several derivations have 

 been ascribed to the term. May not the word sand admit of res- 

 olution into its primitive signification, and mean in this, as in 

 other instances, a sundered crack? A sand-crack may be defined 

 to be a longitudinal division in the fibers of the wall of the hoof, 

 amounting to a flaw simply, or else to a cleft or fissure through 

 the substance of the horn. 



The direction of the crack is slanting, from above downward, 

 and from behind forward, following the course of the fibers of the 

 noof. A sand-crack in the side of the wall slants more than one 

 in front, owing to the greater obliquity of the course of the horny 

 fibers, as we proceed from the toe to the heel of the foot. 



There are two kinds of sand-crack, quarter sand-crack and toe 

 sand-crack, the former occurring in the fore, the latter in the hind 

 foot. At least this is generally the case. It is rare to find the 

 reverse, though there are occasions on which we meet with sand- 

 crack in the toe of the fore-foot and the quarter of the hind foot. 

 It is possible for cracks to occur in other parts of the hoof; but 

 in these two situations it is that veritable sand-crack occurs, and 

 there are here, as we shall find hereafter, special causes for theii 

 production. Let us first consider 



Quarter Crack. 



The situation of this crack is the slanting line of the wall of 

 the hoof, directly opposed to the extremity of the wing of the 

 coffin bone ; and it is oftener found in the inner than in the outer 

 quarter, added to which the hoof in which sand-crack occurs is» 

 always a contracted one, quarter sand-crack, no more than toe 

 sand-crack, never happening in a hoof disposed to obliquity and 

 flatness. The same description of foot which is predisposed to 

 contraction is, for the same reasons, predisposed to sand-crack. 

 There is an obvious connection between contraction and quarter 

 sand-crack. The light, near-the-ground stepping horse, with 

 strong, narrow, upright hoofs, will be equally likely, under cer- 



