DISEASES FROM FAULTY CONFORMATION 163 



Take, again, the vice of contracted heels. Here, in the 

 first place, we have a variety of causes tending to bring 

 about the contraction. With the contraction, and its con- 

 sequent pressure upon the sensitive structures in the region 

 of the quarters and the frog, has arisen a low type of 

 inflammation. The horn of the part has become dry and 

 brittle. The exciting cause of its fracture is found in an 

 excessive day's work upon a hard, dry road, with, perhaps, 

 a suddenly-imposed improper distribution of weight, due to 

 treading upon a loose stone, or a succession of such evil 

 transfers of weight due to travelling upon a road that is 

 rough in its whole extent. 



In their turn, too, such defects of the feet as we have 

 mentioned in the last chapter — as, for example, the foot 

 with the pumiced horn, the foot with abnormally upright 

 heels, or that which is upright on one side only, or crooked 

 — each offers a condition which is predisposing to the for- 

 mation of a sand-crack. In each case it wants but the un- 

 even distribution of the body-weight, which, as a matter of 

 fact, some of these conditions themselves give, to bring 

 about a fracture. 



Apart from the predisposition conferred by conforma- 

 tion, must be remembered the simpler predisposing causes 

 leading to brittleness of the hoof- We refer to the after- 

 effects of poulticing, the moving from pasture to stable, the 

 emigration from a damp to a dry climate, or the alternate 

 changes from damp to dry in a temperate region. Each 

 may have a deteriorating influence upon the horn, render- 

 ing it liable to the condition we are describing. Excessive 

 dampness alone, especially when the animal is called upon 

 to labour at the drawing of heavy loads upon a rough road, 

 is not infrequently a cause. In this case the wet, together 

 with the constant friction of the sharp materials of which 

 the road is made, serves to destroy the varnish-like periople. 

 The wet gains access to the inner structures of the wall, 

 the agglutination of the horn fibres is weakened, and fissures 

 begin to appear. 



Other causes of sand-crack are purely accidental. An 



