276 DISEASES OF BONE. 



frog, to a great extent, of the natural support which it derives from 

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

 than it would be, if the frog were supported ; 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 prominent factor ; if it were, 

 this disease would be particularly 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 the ossification was often confined to the outside quarter, 

 high up on the coronet, while the cartilage of that side of 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 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 the expression be allowed) 

 method of progression. If sidebones be present, there will be 

 little difficulty in deciding the point. If the cartilage of only 



