DISEASES OF BONES 



211 



himself in slipping. The disease may also occur in connection with frac- 

 ture of the bone when the result of extreme violence. 



Symptoms. — When occurring in the bones of the extremities, it is 

 attended with acute lameness and suffering. The parts around the 

 bone are mucli swollen, hot and tender, and considerable difficulty may 

 be experienced in defining the precise stage and nature of the disease. 

 Sooner or later an abscess forms, 

 followed by another and another, from 

 which flows a blood-stained and offen- 

 sive matter. 



Later the bone Ijegins to crumble 

 away, and the debris escapes in 

 granular particles with the discharge. 

 The tendency in these cases is to 

 blood-poisoning, and the formation of 

 abscesses in one or another or several 

 of the internal organs. It is seldom 

 that the patient recovers from such 

 an attack so as to be again useful. 



Chronic Ostitis. — This is the 



form in which ostitis most frequently 

 presents itself in the horse. Ring- 

 bones, some sjjlints, and various other 

 excrescences on the bones of the limbs 

 and other parts of the skeleton are 

 frequently of this nature. 



At first the affected bone becomes 

 porous and spongy (fig. 319), as the 

 result of the inflammatory exudation 

 pressing upon the vascular canals of 

 the bone and promoting their absorp- 

 tion and enlargement. As a result of 

 this the bone tissue becomes changed 

 from a close compact structure to a loose and spongy condition. This 

 is what is known as rarefying ostitis. 



As the inflammation abates, the material thrown out of the vessels into 

 the structure of the bone, by which the rarefaction was produced, is itself 

 converted into bone. 



The effect of this is to change the part from a soft spongy condition 

 to a state of great density and hardness (fig. 320). 



Fig. 319.— Rarefying; Chrouic Ostitis 



