OSSIFICATION OF THE LATERAL CARTILAGES. 331 



many breeders of the best class of cart-horses, being aware of 

 the fact, are careful not to breed from an animal with them. 



High-heeled shoes prove a cause :— 1st. Because the shock 

 received by the heels when the foot comes to the ground is 

 transmitted directly to the cartilages ; 2d. Because the pres- 

 sure upon the heels of the wall is unnatural and excessive, the 

 frog being prevented from bearing its proper proportion ; and, 

 Sd. Because they are pulled inwards and downwards by the 

 sensitive frog being pressed downwards, whilst it horny covering, 

 being removed from the ground, forms no column of support. 



Side-bones are a cause of unsoundness, but all horses so 

 affected should not be condemned on this account, and it may 

 be laid down as a general rule, that if the feet are strong, open, 

 and well developed, the horse showing no lameness should 

 not be condemned for side-bones. But if he is stilty in his 

 action, even without actual lameness, or if the feet be con- 

 tracted, altered in form, weak in the heels, flat or convex in the 

 sole, there should be no hesitation in pronouncing him unsound. 



Occasionally the lighter-bred horse is found to have side- 

 bones, which are usually attended with lameness ; whether lame 

 or not, such an animal is unsound, since he is unfit to perform 

 his ordinary labour, as trotting upon the roads is sure to set up 

 the inflammatory process in the cartilage, and cause lameness. 



To detect these deposits, it is necessary to press upon the 

 cartilages ; naturally, these are yielding and elastic, but when 

 ossified they lose this character, becoming hard, unyielding, 

 and enlarged. The deposition of bone may be uniform, in- 

 volving the whole substance of the fibro-cartilage, or it may 

 be in isolated spots, either at the junction of the cartilage with 

 the pedal bone anteriorly, or involving the posterior borders, 

 forming a hard kernel-like enlargement. 



The anterior side-bone more commonly causes lameness than 

 the posterior one. 



Side-bones differ from ring-bones, both in the structures they 

 involve and the lameness they occasion. Side-bone lameness 

 is characterised by the toe of the foot being first brought to the 

 ground; when both feet are involved, by a shortness of step 

 and want of elasticity or springiness in action, resembling that 

 of navicular disease. 



Treatment. — Bar shoe ; rest, blisters, firing ; and should these 



