GENERAL DISEASES OF THE BONES. 295 



Lameness in both hind Hmbs is marked by the backward 

 position of the fore-feet, the short rest and weak impulse of the 

 hind on the ground, the extension and drooping of the head; 

 and, above all, the difficulty of backing. 



Lameness of the two limbs on the same side determine? a 

 gait approaching the amble or rack, with the firm planting of 

 f.ne opposite members. Lameness of one fore and the opposite 

 hind produces a simple exaggeration of the gait caused by 

 disease in one of these limbs. AVhen the cause of lameness 

 exists in more than one limb it is difficult to make the animal 

 keep the trot. 



In all cases it is well to have the animal driven or ridden so 

 as to heat him, and then keep him perfectly still for half an 

 hour to cool, before completing the examination, as many 

 lamenesses will disappear when the subject is warmed by 

 exercise. 



DISEASES OF BONES. 



These may be divided into : — Injlamtnation of the bone itself 

 {osiiiis), or of its fibrous covering {periostitis), which may result 

 in softening, consolidation ox induration, enlargement, bony growths 

 and tumours, abscess, ulceration and death {necrosis). Besides 

 these there are the degenerations and diseases of bone, such as 

 dejicieticy or extess of earthy salts, with binding or brittleness of 

 the bones ; tubercle, cancer, and sarcomatous, cartilaginous, cystic, 

 vascular, or other tumours, etc. 



But the great mass of bone diseases in the domestic animals 

 consist in inflammation and its results, to which, accordingly, 

 the following remarks will be mainly confined. Every bone is 

 permeated even in its densest parts by an abundant network of 

 minute blood-vessels, and studded throughout with microscopic 

 soft elements (nuclei), which appropriate the suitable materials 

 from the blood and build them up into the hard bony texture. 

 If these nuclei are injured their powers of assimilation are 



