BREEDS OF HORSES 109 



to sidebones (ossified cartilages). Under the descent of the coffin- 

 bone the horny sole sinks a little ; that is, the arch of the sole around 

 the point of the frog, and the wings of the sole become somewhat 

 flattened. All these changes of form are most marked in sound un- 

 shod hoofs, because in them ground pressure on the frog and sole is 

 pronounced ; they are more marked in fore hoofs than in hind hoofs. 



The movement of the different structures within the foot and 

 the changes of form that occur at every step are indispensable to 

 the health of the hoof, so that these elastic tissues must be kept 

 active by regular exercise, with protection against drying out of the 

 hoof. Long continued rest in the stable, drying out of the hoof, and 

 shoeing decrease or alter the physiological movements of the hoof 

 and sometimes lead to foot diseases. Since these movements are 

 complete and spontaneous only in unshod feet, shoeing must be re- 

 garded as an evil, albeit a necessary one, and indispensable if we 

 wish to keep horses continuously serviceable on hard artificial roads. 

 However, if in shoeing we bear in mind the structure and functions 

 of the hoof and apply a shoe whose branches have a wide and level 

 bearing surface, so as to interfere as little as may be with the expan- 

 sion and contraction of the quarters, in so far as this is not hindered 

 by the nails, we need not be apprehensive of trouble, provided the 

 horse has reasonable work and his hoofs proper care. 



Groii'th of the Hoof. All parts of the hoof grow downward 

 and forward with equal rapidity, the rate of growth being largely de- 

 pendent upon the amount of blood supplied to the pododerm, or 

 quick. Abundant and regular exercise, good grooming, moistness 

 and suppleness of the hoof, going barefoot, plenty of good food, and 

 at proper intervals removing the overgrowth of hoof and regulating 

 the bearing surface, by increasing the volume and improving the 

 quality of the blood flowing into the pododerm, favor the rapid 

 growth of horn of good quality; while lack of exercise, dryness of 

 the horn, and excessive length of the hoof hinder growth. 



The average rate of growth is about one-third of an inch a 

 month. Hind hoofs grow faster than fore hoofs and unshod ones 

 faster than shod ones. The time required for the horn to grow from 

 the coronet to the ground, though influenced to a slight degree by 

 the precited conditions, varies in proportiin to the distance of the 

 coronet from the ground. At the toe, depending on its height, the 

 horn grows down in eleven to thirteen months, at the side wall in 

 six to eight months, and at the heels in three to five months. We 

 can thus estimate with tolerable accuracy the time required for the 

 disappearance of such defects in the hoof as cracks, clefts, etc. 



Irregular growth is not infrequent. The almost invariable 

 cause of this is an improper distribution of the body weight over the 

 hoof that is, an unbalanced foot. Colts running in soft pasture 

 or confined for long periods in the stable are frequently allowed to 

 grow hoofs of excessive length. The long toe becomes dished that 

 is, concave from the coronet to the ground the long quarters curl 

 forward and inward and often completely cover the frog and lead 



