114 THE SURGICAL ANATOMY OF THE HORSE 



In those cases where animals turn their toes either inwards or out- 

 wards greater pressure is thrown upon one side of the articulation than the 

 other, and this uneven distribution of concussion predisposes to arthritis 

 and thus to the formation of ringbone. 



Defective shoeing, whereby an even bearing is not provided for the 

 sole, acts in a similar manner. 



Since the defects in conformation indicated above are transmissible 

 from sire and dam to their progeny, a predisposition to ringbone may 

 thus be inherited. 



Occasionally ringbone formation is the result ot traumatic injury to 

 the joint. 



Before the formation of the enlargement the existence of the disease 

 is very difficult to diagnose. In these cases it may usually be discovered 

 by flexing and extending the pastern joint, by manipulating the foot 

 and corona? on the distal extremity of the suffraginis. There is heat 

 in the part, and if pressure be applied there is marked evidence of 

 tenderness. 



The action of the animal should be observed. In those cases where 

 arthritis is commencing towards the front of the joint, the animal goes on 

 the heels, and does not fully extend the joint, in order to relieve pressure 

 on the diseased area. For a similar reason, when the disease is com- 

 mencing towards the back of the articulation he goes on his toes, and 

 limits flexion as much as possible. 



If the disease is commencing anteriorly, there will after a while first 

 be a filling up of the depression under the tendon of the extensor pedis, 

 which is raised to the level of its surroundings, and later a distinct 

 elevation will be present, when there will be no difficulty in detecting it. 

 When the disease commences posteriorly and on one side only, an 

 elevation more or less nodular in shape makes its appearance just behind 

 the corresponding edge of the tendon. This forms much more quickly 

 than that under the tendon, since the pressure of the tendon retards the 

 growth of the exostosis in the latter case. 



