8 Jan., 1908.] 



Diseases of Farm Animals. 



59 



The two latter forms are the most grave on account of the great 

 liability to infection of the wounds with septic matter, and the spread of 

 the consequent suppuration to the seat of the fracture. 



Any of the bones of all domestic animals are liable to be fractured,* 

 but it is the point of the hip and the bones of the limbs, especially the 

 pastern bones, which are most frequently broken ; more rarely those of the 

 face, skull and back. From the nature of their activities, fractures are 

 sustained by the horse and the dog more frequently than by cattle and 

 sheep. In all animals however the rule is general that fractures are of 

 more common occurrence in the old than in the immature or young ; this 

 because of the increasing fragility or brittleness accompanying the harden- 

 ing of bone as age increases. 



Repair or " Knitting " of Fractures. 



A full exposition of the process of repair of broken bones would be 

 redundant in a work of this character, and for such as require it reference 

 to a special treatise on pathology is recommended. It will suffice here to 

 coiihne attention to- the salient steps in the process of union. A preliminary 

 remark ought to be made however with a view of disipelling a very pre- 

 valent idea amongst horsemen, that in horses fractured bones never, or 

 only tardily, unite. In point of fact, provided the fractured bones can be 

 kept in a state of quietude, fractures " knit " more rapidly in horses than 

 in man or other animals. This is on account of their possessing that 

 peculiar bone forming tendency described in a previous chapter (page 266) 

 as an " ossific diathesis," and which is also exemplified in the readiness 

 with which splints, ringbones, spavins and other bony outgrowths are 

 developed. That many horses, as also other animals, do not recover from 

 severe fractures is due solely to the great difficulty in keeping the seat 

 of fracture in a state of rest in animals that cannot be restrained from 

 movement bv other than mechanical means. The human surgeon adjures 

 his patient, under pain of permanent deformity, to remain quiet and avoid 

 movement of the fractured part. No such method of control can be prac- 

 tised with animals and except some effective device for fixing and main- 

 taining the bones in apposition can be adopted their union is often 

 prevented. 



Fig. 4. Repair of fractures. Bone [tibia) showing oblique fracture with '• soft 

 callus" between fractured ends, |«), and •'provisional callus" surrounding. (After 

 Williams.) 



On the occurrence of a fracture, a condition of inflammation,- with 

 exudation, of the parts surrounding is set up. At the end of about three 

 days and from then until the twelfth day the inflamed blood vessels in the 

 vicinity exude a soft lymph which encases the broken ends of bone and 



* The author has had the unusual experience of encountering a fracture of the 

 hardest bone in the body — the -petrosal or bone of the ear. 



