FEACTUBES OF BONES. 295 



Lastly, although good union may take place, yet in the outset this is 

 always very doubtful, and therefore when a serious accident occurs, it 

 is always questionable whether the probability of thorough recovery is 

 great enough to be worth the risk and cost of keep and treatment. 



For these reasons we shall not enter into the treatment of the fracture 

 of such important bones as the radius and cannon bone in the fore-leg, 

 or the tibia, femur, or cannon bone of the hind leg. Broken back is 

 obviously incurable. 



Fractures, however, of minor bones, or of bones which are so confined 

 by ligaments or muscles, that the fractured parts are little liable to dis- 

 location, even if fractured, are often worth treatment. 



585. Causes of Fracture. 



The causes of Fracture may be included under two heads, namely 

 violence to the bone itself or to some adjacent part, such as occurs in the 

 case of falls or kicks ; and less commonly from excessive muscular strain. 

 The sesamoid bones for instance are occasionally broken by the stress 

 thrown on them by the suspensory ligament. 



In some horses, as in some men. the bones appear to be abnormally 

 fragile, probably from imperfect nutrition and fatty degeneration. The 

 liability to fracture also increases greatly in old age. 



586. Symptoms of Fracture. 



Fractures are distinguished by some or all of the following symptoms. 



1st. The bone is displaced. Pressure or weight thrown on it causes 

 still further displacement. In the case of long bones the broken ends, if 

 the fracture is right across, may pass each other, and thus the limb will 

 be shortened. 



2nd. The fractured limb partially or entirely loses its power of volun- 

 tary movement ; but by external force it can be moved, more readily and 

 in a greater variety of directions than when sound. 



3rd. When a broken bone is thus moved, the fractured surfaces may 

 be felt and heard to grate on each other or " crepitate." This crepitation 

 is especially noticeable if the fractured surfaces are rugged, and still 

 more in comminuted fractures. In fractures of an important bone there 

 will also generally be twitching of the neighbouring muscles. 



■ith. From rupture of the adjacent blood-vessels and consequent escape 

 of blood, or from laceration of the neighbouring soft parts there is 

 usually a considerable swelling about a broken bone. From the same 

 causes the skin, where it is visible, may be discoloui-ed, and the parts hot 

 and tender. 



687. Treatment. 



The first object is to " set " or bring together the broken ends of the 

 bone as soon as possible. When the bones can be properly replaced at 

 once, the fractured surfaces are thereby prevented from grating against 



