PEACTTJEES. 215 



The relation between sundry idiosyncrasies and diatheses and 

 a liability to fractures is too constant and weU established a path- 

 ological fact to need more than a passing reference. The history 

 of rachitis, of melanosis, and of osteo-porosis, as related to an 

 abnormal frangibility of the bones, is a part of our common medi- 

 cal knowledge. There are few persons who have not known of 

 cases among their friends of frequent and almost spontaneous 

 fractures, or at least of such as seem to be produced by the 

 slightest and most inadequate violence, 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 diseases as caries, tuberculosis, 

 and others of the same class. 



Occasional or "efficient" causes of fracture are in most 

 instances external traumatisms, as violent contacts, collisions, 

 falls, etc., or sudden muscular contractions. These external acci- 

 dents are various in their character, and are usually associated 

 with quick muscular exertion. A violent, ineffectual effort to 

 move too heavy a load ; semi-spasmodic bracing of the frame to 

 avoid a fall or resist a pressure; a quick jump to escape a blow; 

 stopping too suddenly after speeding; struggling to liberate a 

 foot from a rail — perhaps to be thrown in the effort — -aU these are 

 familiar and easy examples of accidents happening hourly, by 

 which our equine servants become sufferers. We may add to 

 these the fracture of the bones of the vertebrae, occurring when 

 a patient is cast for the purpose of undergoing a surgical opera^ 

 tion, quite as much the result of muscular contraction as of a pre- 

 existing diseased condition of the bones. A fracture occurring 

 under these circumstances may be called with propriety indirect, 

 while one which has resiolted from a blow or a faU differently 

 caused is of the direct kind. 



The symptoms belonging to the existence of fracture vary ac- 

 cording to the site of the lesion. In case of its being on a bone 

 of the extremity there is irregularity in the performance of the 

 functions of the apparatus to which the fractured bone belongs, 

 and as a necessary consequence of the existing lesion, lameness 

 more or less marked. If the broken bone belongs to one of the 

 extremities, the impossibility of the performance of its natural 

 function, in sustaining the weight of the body and contributiag to 

 the act of locomotion, is usually complete, though the degree of 



