TYPES AND MARKET CLASSES OF LIVE STOCK 359 



The horny frog does not come in contact with the sole horn 

 except at its apex. It is tough, elastic, and rather soft horn. 

 The upper part of the horny frog has an elevation or ridge and 

 on the bottom there is a corresponding notch or groove. The 

 horny frog grows from the fleshy frog, which is that part of 

 the pododerm just above the horny frog. 



The preceding discussion of the parts of the hoof and podo- 

 derm may be summarized as follows: 



[ Perioplic layer, produced by perioplic ring. 



1. Wall 4 Coronary layer, produced by coronary cushion. 



[ Laminous layer, produced by fleshy laminae. 



2. Sole, produced by fleshy sole. 



3. Frog, produced by fleshy frog. 



All parts of the hoof grow downward and forward with 

 equal rapidity, the rate of growth being largely dependent upon 

 the amount of blood supplied to the pododerm. Abundant and 

 regular exercise, good grooming, moistness and suppleness of 

 the hoof, going barefoot, plenty of good food, and at proper 

 intervals removing the over-growth of the hoof and regulating 

 the bearing surface all these, by increasing the volume and 

 improving the quality of blood flowing into the pododerm, favor 

 the rapid growth of horn of good quality. Lack of exercise, 

 dryness of the horn, and excessive length of the hoof hinder 

 growth. The average rate of growth of the hoof is about one- 

 third of an inch a month. Irregular growth often occurs. This 

 is almost always due to an improper distribution of the body 

 weight over the hoof, that is, an unbalanced foot. One auth- 

 ority on this subject says: "If breeders were more generally 

 cognizant of the power of overgrown and unbalanced hoofs 

 to divert the lower bones of young legs from their proper direc- 

 tion, we might hope to see fewer knock-kneed, splay-footed, 

 pigeon-toed, cow-hocked, interfering, and paddling horses/' 



Characteristics of a healthy foot. A healthy foot is equally 

 warm at all parts, and is not tender under pressure with the 

 hands. The coronet is soft and elastic at all points and does 

 not project beyond the surface of the wall. The wall is straight 

 from coronet to ground, so that a straight-edge laid against 

 the wall from coronet to ground parallel to the direction of the 

 horn tubules will touch at every point. The wall should be 

 covered with the outer varnish-like layer of horn called the 

 periople, and should show no cracks or clefts. Every hoof shows 

 "ring formation," but the rings should not be strongly marked 



