278 DISEASES OF BONE. 



the ground. Hence, the jDlantar cushion is forced further down 

 than it would be, if the frog were supj)orted ; and strain is put on 

 the lateral cartilages, with the frequent result of inflammation and 

 ossification. The nature of the work which cart-horses do, also, 

 renders them liable to suffer from injury to the lateral 

 cartilages of their fore feet, by their drivers carelessly 

 letting down the shafts of carts, and by other horses treading on 

 their coronets when ploughing. Concussion cannot be a promi- 

 nent factor; for if it were, this disease would be jDarticularly 

 frequent among cab horses and fast trotters, which, however, do not 

 often suffer from it. Among saddle-horses, one kind of foot is 

 not more prone to sidebones than another, apparently because 

 sidebones in them is almost always produced by injury 



The fact that injury plays a large part in the production of 

 sidebones, is shown by the frequency of this disease in horses im- 

 ported into India from the Colonies; the evident cause being 

 tread from over-crowding. In such cases of sidebone, the cartilage 

 on the outside quarter is the one which is usually affected. In 

 these instances, I have often noticed that the ossification was 

 confined to the outside quarter, high up on the coronet, while 

 the cartilage of that side at the heel still retained its elasticity. 

 I have known sidebone caused by overreach. 



The greater liability to contract sidebones shown by the fore 

 legs, as compared to the hind ones, appears to me to be chiefly due 

 to the fact that the lateral cartilages of the former are more 

 largely developed and are more exposed to injury than those of 

 the latter. 



SYMPTOMS. — ^The ossification, whether local or general, can be 

 readily detected by pressing the coronet, just above the heels, and 

 along the quarters (Fig. Ill), with the fingers and thumb. The 

 cartilages, naturally soft and yielding, will, when ossified, be 

 hard and inelastic. In the early stage, there will be heat and 

 tenderness, without special hardness, which will become gradually 

 established in the part with the development of the disease. 

 The ossification, when it occurs on, and is confined to, the quarters, 

 may be mistaken for ringbone, from which it can be distinguished 

 by the fact of its standing out as a ridge, clear from the short 

 pastern bone. If lame, the horse goes " short," on the toe, and 

 in a style of action which somewhat resembles the gait of navicular 

 disease, but is not so quick in the removal of the foot from the 

 ground ; in fact, it is a " stumpier " (if I may be allowed the 

 expression) method of progression. If sidebones be present, there 

 will be little difiiculty in deciding the point. If the cartilage of 

 only one side is affected, the animal will generally '^ dish " the 



