50 



HORSESHOEING. 



Fig. 30. 



lower surface of the plantar cushion, and in the region of the 

 bulbs (e) passes insensibly into the perioplic band. In com- 

 parison with the fleshy sole, it has much finer and shorter villi 

 and contains fewer blood-vessels. It secretes the soft, horny 

 frog. 



(c) The horn capsule or hoof (Fig. 30) is the entire mass 

 made up of the horn-cells secreted from the whole surface of 



tlie pododerm, and next 

 to the shoe is the organ 

 with which the horse- 

 shoer has most to do. 

 The horn capsule or hoof 

 is nothing more than a 

 very thick epidermis that 

 protects the horse's foot, 

 just as a well-fitting shoe 

 protects the human foot. 

 The hoof of a sound foot 

 is so firmly united with 

 the underlying pododerm 

 that only an extraordin- 

 ary force can separate 

 them. In its normal con- 

 dition the hoof exactly 

 fits the 'soft structures 

 within it; hence it is 

 evident that local or 

 general contraction of the hoof must produce pressure on the 

 blood-vessels and nerve^endings of the pododerm, disturb the 

 circulation of the blood and the nutrition of the foot, and 

 cause pain. 



The hoof is divided into three principal parts, which are 

 solidly united in the healthy foot, — ^namely, the wall, the sole, 

 and the frog. That part of the hoof which is almost wholly 

 visible when the foot is on the ground (Fig. 30, h, c), and which 



Side view of hoof recently removed: a, the perioplic 

 horn-band; it is swollen from prolonged maceration in 

 water; the upper border shows adhering hairs; the 

 inner surface (perioplic groove) presents many minute 

 openings; a', the perioplic horn-band broadens in 

 passing over the bulb or glome of the heel, and is 

 finally lost in the horny frog; a", section of wall re- 

 moved. That part of hoof on the right of 6 is called 

 the toe; between 6 and c is the side wall or "mamma," 

 and between c and d the "quarter;" e, projecting 

 horny frog;/, coronary groove with numerous minute 

 openings; g, keraphyllous layer of the wall (horny 

 leaves) . 



