General Diseases of Bones, Joints and Muscles. 389 



tion there may be little or no lameness, thougli usually 

 there is a halt on the affected limb when trotted on a hard 

 surface. The affected portion of the bone is tender to 

 pressure or percussion, and is the seat of swelling at first 

 soft and yielding, but later hard and resistant. In the 

 severer forms the bone itself is softened, extensive exuda- 

 tion of lymph takes place around it, and the investing soft 

 structures become the seat of violent inflammation and 

 swelling ; lameness is then extreme. In the slighter and 

 chronic cases there is no disturbance of the general health, 

 but in the more acute and severe, intense and even fatal 

 irritative fever may come on. 



When suppuration takes place in the interior of a bone 

 the matter may" remain imprisoned indefinitely, the spot 

 being marked by a general increase of the bone, and lame- 

 ness persists. If suppuration takes place between the 

 bone and its fibrous covering the danger is even greater, 

 for the matter is liable to separate the bone and mem- 

 brane, producing further inflammation or ulceration, or 

 even death of the bone — the supply of blood being cut off. 

 The superficial abscess is to be detected by its fluctuation 

 beneath the fingers, as in abscess of soft parts. 



Ulceration may raeult from pressure of matter, etc., or 

 from exposure to the air. If without external opening, it is 

 not easily recognized, but there is lameness and tenderness, 

 with little alteration of the surface of the bone, or the 

 presence of slight bony deposits alternating, it may be, 

 witli soft open spaces. If the ulcerated bone is open to 

 the air, it is found to be softened in texture, breaking down 

 readily under the pressure of a probe, and in the centre of 

 the ulcerous cavity rounded bony deposits are felt, as 

 evidence of an effort at repair. The discharge is then 

 ichorous, and abounds in gritty particles and earthy salts. 

 If this discharge has commenced to decompose it smells 

 badly. 



Death of bone is always associated with an open sore 

 discharging a very foetid ichorous fluid, with gritty parti- 



