410 Types and Market Classes of Live Stock 



laminous layer. The perioplic layer is very thin. It is varnish-like 

 in appearance and forms the surface or crust of the wall. Its function 

 is to preserve the moisture of the foot and to absorb moisture. A 

 horse working in sand or dust usually has this outer layer worn away. 

 The coronary layer forms the real basis of the wall. At the heels it 

 is deflected forward to form the bars of the hoof. The angle between 

 the wall and bar is thickened and is called the buttress. The function 

 of the bars is to react against contraction of the heels. The inner or 

 laminous layer of the wall horn is not tubular. It is termed "laminous" 

 because it has the appearance of the leaves of a book. There are 500 

 to 600 of these laminae which extend from the top of the hoof to the 

 sole. It is less thick than the coronary layer, but, like it, is deflected 

 forward at the heels to help form the bars. 



Fig. 154.— The parts of the hoof. 1, Wall; 2, sole; 3, branch of the sole; 4, 

 bar; 5, buttress; 6, frog; 7, cleft of the frog; 8, bulbs of the heels. 



Growth of the wall. — At the lower end of the pastern, running 

 along the edge of the hair from one heel around the toe to the other 

 heel, is a narrow ridge of pododerm, i^ to >^ of an inch wide, 

 called the perioplic ring. (See Fig. 153.) It consists of papillae, 

 which are microscopic nobs or nodules, and from each papilla a shaft 

 of horn grows downward, forming the periople of the wall. Like the 

 periople, the coronary layer grows downward from a band of pododerm 

 at the top of the hoof. This band is called the coronary cushion, and 

 it lies just below and parallel to the perioplic ring. (See Fig. 153.) 

 At the heels it is deflected forward where it produces the horn of the 

 bars. The laminous horn is produced by that part of the pododerm 

 known as the fleshy laminae; these laminae extend up and down be- 

 tween the coronary cushion and the sole. The fleshy laminae of the 

 pododerm and the laminous layer of the wall horn dovetail together, 

 thus holding the hoof securely to the foot. 



