90 OF THE DISEASES 



I 



broad shoe continued well to the heels, as a means 

 of preventing or relieving navicular disease. 



This objection may easily be disposed of. A 

 large portion of the jar and concussion in the 

 horse's frame is due to the presence of iron shoes 

 on his feet. This jar is especially felt at the heels, 

 where the shoe interferes with the action of the 

 natural elastic pad or frog, which nature has pro- 

 vided in that part of the foot in order to diminish 

 concussion. The absence of iron at the heels, the 

 very seat of navicular disease, must lessen the jar. 

 Again, tips, by promoting the enlargement and 

 development of the frog and bars, must in this 

 way also tend to diminish concussion, whilst the 

 growth and development of the posterior parts ot 

 the foot will lessen the liability to strain on the 

 flexor perforans tendon. 



Disease in the navicular bone has also been sup- 

 posed sometimes to have its origin in an accidental 

 injury or blow on the posterior part of the foot ; 

 but it is difficult to understand how a bone so com- 

 pletely embedded in the interior of the foot and 

 so thoroughly protected on every side, can be 

 injured by any external violence. 



Others ao^ain have thouoht that the disease 

 originates spontaneously in the bone. Bones, how- 

 ever, are not liable to disease without some pre- 

 disposing cause. When disease originates in a 

 bone, concussion or some injury as from a blow 



