PRINCIPLES OF SHOEING. 463 



Upright feet, which would sink deep at every step. But certainly they 

 would not stand much wear. 



The high-bred horse, which is a native of the arid sandy plains of 

 Arabia, must in a state of nature travel many miles every day in search 

 of food and water. Nature has accordingly furnished him with feet more 

 capable of withstanding wear. Hill ponies often have feet almost like 

 those of donkeys. Such feet are suitable for rough rocky hills. 



9-44. Effect of Rasping the Crust. 



1st. Of rasping the crust high up, where the fibres are vitalised 

 (A, fig. 2). 



Rasping produces two evils : 1st, the outer and strongest layers of 

 fibres are destroyed ; and 2nd, the gluey superficial layer which overlies 

 the outside of the crust is destroyed, and then the moisture of the horn, 

 which is essential to its toughness, escapes. In consequence, the horn 

 becomes brittle and then shrinks and contracts. Again, the moisture 

 having escaped, the horn becomes hard. 



Having become hard and contracted, the horn then presses unduly on 

 the vascular and sensitive parts within, especially on the sensitive laminae, 

 and causes them to become hot, inflamed, and ultimately diseased. 

 We recognise the earlier of these effects in the foot being hot. I do not 

 say that the permanent and more injurious results above mentioned will 

 ensue in a day or in a month, or even perceptibly in a year, but surely 

 and slowly the maltreatment produces and must produce an ill effect on 

 the vascular and sensitive structures of the foot. 



2nd. Of rasping the crust below the point to which vitality extends 

 (A, fig. 3, Plate 48). 



What harm is there in that ? it may be said. Well, two evils result 

 the one mechanical, the other vital through injury to the mechanical 

 arrangements of the foot. 



The width of the crust " proper," taken by itself, is about half an inch. 

 But including the fibres, which interlace it with the laminae, it may be 

 said to be about three quarters of an inch in width. These latter fibres 

 are not so strong as those of the crust, but they are capable of sustaining 

 some weight. 



On this three quarters of an inch has to be borne the greater portion 

 of the weight of the horse and his rider, and the pounding and concussion 

 occasioned by fast riding on hard roads. Now three quarters of an inch 

 is not a great width on which to sustain all this weight and concussion. 



Two evils, the one mechanical, the other vital, as I said above, result 

 from rasping the crust. Its width is probably diminished to half an 

 inch ; and moreover, the strongest fibres have been destroyed. This re- 

 duced width is one third less than nature intended. And nature is always 

 right. In consequence of diminished width and strength, the crust be- 

 comes insufficient to carry the weight of the horse. Hence undue con- 

 cussion, heat, inflammation, and disease. The first portion of the injury 

 is mechanical ; the second, a result of the mechanical injury, is vital. 

 The sensitive internal structures are injured. Moreover, the strongest 



