298 BUREAU OF ANLMAL INDUSTRY. 



result of the treatment iu the fact that from various causes, such as 

 muscular contractions or excessive motion, the bony fragments do 

 not maintain their mutual coaptation, but become separated at the 

 ends, which makes it necessary to add another descriptive term — icith 

 dixj^Iacement. And these words again suggest the negative, and 

 introduce the term vntliout dis place m-ent^ when the facts justify that 

 description. Furthermore, a fracture may be intraartlcxdar or extra- 

 articidar, as it extends into a joint or otlierwise, and once more, intra- 

 j)e)'e'ofife(d, when the periosteum remains intact. Finall}", there is no 

 absolute limit to the xvie of descriptive terminology in the case. 



The condition of displacement is largely influential in determining 

 the question of treatment, and as affecting the final result of a case of 

 fracture. This, however, is dependent upon its location or whether 

 its seat be in one or more of the axes of the bone, in its length, its 

 breadth, its thickness, or its circumference. An incomplete fracture 

 may also be either simple or comminuted. In the latter case the frag- 

 ments are held together by the periosteum when it is intact, and the 

 fracture in that case belongs to the intraperiosteal class. At times, 

 also, there is onlj- a simple fissure or split in the bone, making a con- 

 dition of much difficulty of diagnosis. 



Causes. — Two varieties of originating cause may be recognized in 

 cases of fracture. The}^ are the predts'poslng and the occasional. As 

 to the first, different species of animals differ in the degree of their 

 liability. That of the dog is greater than tliat of the horse, and in 

 horses the various questions of age, the mode of labor, the season of 

 the year, the portion of the body most exposed, and the existence of 

 ailments, local and general, are all to l)e taken into account. 



Among horses, those emploj^ed in heavy draft work or that are 

 driven over bad roads are more exposed than light-draft or saddle 

 horses, and aniumls of different ages are not equally lial)le. Dogs 

 and young horses, with those which have become sufficiently aged for 

 their bones to have acquired an enhanced degree of frangibility, are 

 more liable than those which have not exceeded the time of their 

 adult prime. The season of the 3'ear is undoubtedly, though in an 

 incidental v/aj', an important factor in the problem of the ctiolog}^ of 

 these accidents, for though the}'- may be observed at all times, it is 

 during the months when the slippery condition of the icy roads renders 

 it difficult for both men and beasts to keep their feet that thej^ occur 

 most frequently'. The long bones, those especially which belong to 

 the extremities, are most frequentl}' the seat of fractures, from the 

 circumstance of their superficial position, their exposure to contact 

 and collision, and the violent muscular efforts involved both in their 

 constant rapid movement and their labor iu the shafts or at the pole 

 of heavy and heavily laden carriages. 



The relation between sundrv idiosvncrasies and diatheses and a lia- 



