303 



Among horses, those employed in neavy draught work or that are 

 driven over had roads are more exposed than light-draught or saddle 

 horses, and animals of different ages are not eqnall}" liable. 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 year is undoubtedlj^, though in an 

 incidental way, an important factor in the jDroblem of the etiology of 

 these accidents, for though they may be observed at all times, it is 

 during the months Avhen the slippery condition of the ic}' roads renders 

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

 most frequently. The long bones, those especiallj^ which belong to 

 the extremities, are most frequently the seat of fractures, from the 

 circumstance of their superficial j^osition, their exposure to contact 

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

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

 of heavy and heavily laden carriages. 



The relation between sundrj^ idiosyncrasies and diatheses and a lia- 

 bility to fractures is too constant and well established a pathological 

 fact to need more than a x)assing reference. The history of rachitis, 

 of melanosis, and of osteo-porosis, as related to an abnormal frangi- 

 bility of the bones, is a iiart of our common medical knowledge. 

 There are few persons who liave not known of cases among their 

 friends of frequent and almost si)ontaneous fractures, or at least of 

 such as seem to be j)roduced bj^ the slightest and most inadequate vio- 

 lence, and there is no tangible reason for doubting an analogous 

 condition in individuals of the equine constitution. Among local 

 predisposing affections mention must not be omitted of such bony dis- 

 eases as caries, tuberculosis, and others of the same class. 



Occasional or "efficient" causes of fracture are inmost instances 

 external traumatisms, as violent contacts, collisions, falls, etc., or 

 sudden muscular contractions. These external accidents are various 

 in their character, and are usually associated with quick muscular 

 exertion. A violent, ineffectual effort to move too heavy a load; a 

 semispasmodic bracing of the frame to avoid a fall or resist a i)res- 

 sure; a quick jump to escape a blow; stojij^ing too suddenly after 

 speeding; struggling to liberate a foot from a rail, i^erhaps to be 

 thrown in the effort — all these are familar and easy examples of acci- 

 dents happening hourlj^ by which our equine servants become suffer- 

 ers. We ma}" add to these the fracture of the bones of the vertebra, 

 occurring when casting a patient for the j^urpose of undergoing a 

 surgical operation, quite as much the result of muscular contraction 

 as of a i)reexisting diseased condition of the bones. A fracture 

 occurring under these circumstances may be called with propriety 

 indirect, while one which has resulted from a blow or a fall differently 

 caused is of the direct kind. 



