154 



DISEASES OF THE BONES AND ARTICULATIONS. 



and growth, are much more vascular, and contain a greater 

 quantity of animal matter than the bones of those of mature 

 age ; they are consequently unable to stand the shocks of con- 

 cussion, to which they are subjected in their training. 



Sore shins may affect the whole shaft of the bone (see Yig. 21), 

 and may be so excessive as to cause necrosis to supervene ; but 

 usually the inflammation is circumscribed and confined to the 

 lower extremity and anterior portion of the bone. The leg with 



which the animal leads in the gallop is 

 more liable to be affected than its fellow. 

 Symptoms. — Lameness occurring after 

 a gallop, insidious at first; the horse 

 restless, shifting his weight from one 

 leg to the other if both legs are affected, 

 or, if only one, standing with his foot 

 pointed. If the inflammation is acute, 

 there will be fever, with acceleration of 

 the pulse and respiratory movements, and 

 the bones are sensitive when pressed 

 upon. Swelling is an early symptom; at 

 first it is elastic, tense, and doughy to the 

 touch ; it depends on the thickening of 

 the periosteum ; and on the presence of 

 a subperiosteal exudate ; afterwards, the 

 swelling may become oedematous, from 

 effusion into the areolar tissue external 

 to the periosteum, but it always main- 

 tains the elastic feel underneath the 

 oedema. 



If the subperiosteal exudation is 



very great, and the swelling involves a 



large extent of the surface of the bone, 



the most active treatment must be 



employed in order to prevent necrosis. 



In some rare cases, the exudate becomes 



converted into a thin, sanious matter, 



which corrodes the surrounding tissues, 



causing great febrile disturbance, and may cause the death of 



the patient, from its absorption into the general circulation. 



In the less acute cases, where the cause has been less severe, 



Fig. 21. — Sore shin. 



