330 



DISEASES OF THE FEET. 



be said to be forced to expand when the foot is on the ground, 



aud that they actively assist contraction when the weight, which 

 forcea the sensitive frog upwards aud outwards, is removed from 

 the foot. 



It must not be understood that I am advocating the theory 

 that the foot expands upon its inferior surface ; that supposition 

 is now entirely disregarded ; but no one can deny, what is ap- 

 parent to tlie most ordinary observer, that the foot expands at 

 the oorouet and heels ; not the horny foot, but the soft parts of 

 the heels and coronet. To prevent undue expansion of these, 

 tlie lateral cartilages are placed as elastic sides. 



Ossijication of tlie Lateral Cartilages. — As already stated, side- 



Tio. 68 sho-W3 osaifi.-.ation of the lateral cartilages, ■with 

 fracture of the altered etnicture upon one side, at its junc- 

 tion Trith the pedal bone. 



bones are commonly met with in heavy draught horses; indeed, 

 a great majority of this class is found so affected by the time the 

 animal is six or seven years old ; and this seems to arise from 

 the over-expansion of the cartilages caused by the great weight 

 of the animal. The process of ossification is very often a slow 

 one, unaccompanied by any acute inflammatory actiob, giving 

 the animal no pain, and causing no lameness. 



The causes of ossification of these cartilages are^iereditaiy 

 tendency, and shoeing with high calkins. It is generally ad- 

 mitted that the predisposition to side-bones is hereditary, and 



