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agents in causing the contraction of the heel ; for, when the pressure is 

 removed from their inner surfaces, they tend to assume their natural 

 position, in virtue of their elasticity, and the pressure they exert upon the 

 sensitive frog, forces the heel into its original shape. 



Cartilaginous Apparatus of the Horse's Foot. 



A, external face of the lateral cartilage ; B, superior border ; C, posterior border ; 



D, anterior lateral ligament bordering the cartilage in front ; E, flexor 



tendons; F, extensor tendons ; G, coffin bone. 



Briefly, then, they may be said to expand, when the foot is on the 

 ground ; and to assist contraction, when the weight which forces the 

 sensitive frog upwards and outwards, is removed from the foot. Professor 

 Williams, in short, holds that these lateral appendages act, as it were, 

 as " elastic sides," preventing undue expansion of the soft parts of the 

 coronet and heel. 



The term side-bone, we have said, denotes a bony or ossified 

 condition of the lateral cartilages. This condition is commonly met with in 

 heavy draught horses, and is but rarely seen in the lighter breeds. It is 

 almost always met with in the fore feet, though in rare instances it has been 

 observed on the hind ones. In the latter situation, it is never known to 

 occasion lameness. The lateral cartilages are of lesser size here, and, being 

 of less functional importance, are consequently much less liable to become 

 diseased. 



We may now proceed in the first place to examine the causes of this 

 very common form of disease among our heavy draught horses. Some 

 authorities compute that over fifty per cent, of the heavy draught horses 

 become affected with this disease by the time they have attained the age of 

 six or seven years ; but, according to our own computation, sixty 

 per cent, is not an exaggerated estimate of this common form of morbid 

 action. Why is this } Indubitably this morbid process depends, as do 



