DISEASES OF BONES 219 



METACARPAL PERIOSTITIS— SORE SHINS 



This is an ailment of common occurrence in race-horses, but com- 

 pai'atively seldom seen in other varieties. The greater liability of the 

 one over the others is associated with early training, while the bones are 

 in active growth, and by their imperfect development specially susceptible 

 to injury and disease. 



The term " sore shins" has been applied to it on account of the extreme 

 tenderness and pain found to exist in that part of the leg between the 

 knee and the fetlock joint. The mischief, however, does not always 

 stop here, but may also involve the large, and sometimes the small pastern 

 bones, developing there the same soreness of the surface, and in some 

 instances provoking an outgrowth of bony matter in the form of ring-l)one. 



The fore-limbs, for reasons presently to be stated, are more particularly 

 the seat of sore shins, although the hind ones are not wholly exempt. 



Pathologically considered, " sore shins" at the outset consists in an 

 inflamed condition of the periosteum, or covering membrane of the bone; 

 but unless soon relieved from the operation of the cause, the shin-bone 

 itself soon shares in the disease. At this time the pain and lameness 

 become aggravated, the periosteum is much thickened, and a rough bony 

 growth appears on the surface beneath it. 



Causes. — Youth, and want of development and power of resistance 

 in the bone is, as we have observed, the predisposing element to sore 

 shins, and this is materially intensified when, as sometimes occurs, there 

 is a hereditary predisposition to the morbid growth of bone. 



The exciting cause is to be found in concussion, arising from the 

 forcible impact of the feet with the hard ground in the act of galloping, 

 when the "jar" is transmitted along the shaft of the bones, whose cover- 

 ing becomes irritated and inflamed. It will, therefore, be seen that in 

 proportion as the ground is hard, and the weight carried by these juveniles 

 is considerable, so will be the liability to injury. It is for this reason 

 that the disorder appears duinng seasons of drought, when the ground is 

 dry and resisting instead of being soft and spongy. 



Symptoms. — The lad who habitually rides a horse in his daily work 

 is often the first to detect the oncoming of this disease. He recognizes 

 a growing sense of discomfort arising out of a change in the animal's 

 action and spring. Then it soon becomes obvious that he is going short 

 in his stride, and some difliculty is experienced in setting him going and 

 keeping up the pace. Examination of the legs at this time reveals more 

 or less heat and soreness along the course of the canons, and especially 



