DISEASES FKOM 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, per- 

 haps, 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 conformation, 

 must be remembered the simpler predisposing causes lead- 

 ing 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 



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