DISEASES OF BONES 213 



seldom affected. For the above reasons necrosis is found to implicate 

 the front of the shin or canon bones both in the fore and hind limbs, 

 and also the lower jaw-bone and the ril)s. The shin-bones in the act 

 of jumping are not unfrequently brought into forcible contact with posts 

 and rails, gates and stone walls, or they are injured by kicks from other 

 horses, &c. The most common seat of the disease is the lower jaw at 

 the resting-point of the bit, where the resistance to runaways, pullers, 

 and hard-mouthed horses is specially applied. In addition to e.xternal 

 violence necrosis may be induced by acute inflammation of bone in any 

 part of the skeleton. 



Symptoms. — -Where an injury is inflicted on bone sufticiently severe 

 to destroy its vitality the immediate efl"ects are more or less swelling, 

 heat, and tenderness of the part, and when involving the bones of the 

 extremities more or less lameness. In superficial bones the swelling 

 is not generally considerable and may soon altogether subside, leaving 

 behind, however, an abiding tenderness of the part. Sooner or later the 

 swelling reappears, or if still present becomes considerably increased, 

 while the heat and soreness return with greater severity than before. As 

 the inflammation becomes more and more severe an abscess is formed, 

 which may break, and heal, and break again and again, and finally 

 resolve itself into a chronic running sore. During this time the dead 

 piece of bone is being separated from the living. If a probe be passed 

 into the wound the harsh grating of its point on the dead bone will be 

 felt. These cases are always of a protracted nature, and when neglected 

 extend over months. 



When the lower jaw is the seat of injury the animal jibs when ridden 

 or driven, or turns the head towards the side on which the disease exists. 

 The saliva is raised into foam by champing of the jaws, and may be stained 

 with blood. Feeding is rendered painful, and swelling appears on the outer 

 part of the injured bone and extends for some distance around it. If the 

 finger be applied to the spot a wound in the gum will be found correspond- 

 ing to the injured part, through which the dead fragment is readily felt, 

 and if completely detached may be brought away. The odour emitted in 

 these cases is usually very off"ensive. Although sloughing may have com- 

 pletely taken place, and the dead bone have been quite detached from the 

 living, it may still be retained unless means are adopted for its removal. 



Treatment. — Here the aim and object of treatment should be to 

 remove the dead bone as speedily as possible, but no attempt should 

 be made in this direction until nature has defined its limits and well- 

 nigh completed its separation from the living. If after this it is allowed 

 to remain it becomes a source of irritation, und the wound continues to 



