AND HIS DISEASES. 19 



knee-joint ; in fact, every joint in the body is liable to be 

 rendered stiff by anchylosis. 



Symptoms are enlargement round the joint, which is stiff 

 and inflexible, and in most cases the animal is lame. 



Treatment. — Nothing can restore the motion of the joint. 

 Punching is sometimes tried. 



CAEIBS OF BONE. 



Caries is generally defined to be ulceration or disintegra- 

 tion of the bony texture, and is supposed to be ulceration 

 of the soft tissues ; but this is not, histologically speaking, 

 correct. We find in caries the bone undergoes several very 

 marked changes — it decreases in density, (owing to a de- 

 crease in the proportion of organic matters entering into 

 its composition,) and presents a peculiar worm-eaten appear- 

 ance, which enables us always to recognise a carious bone in 

 the dried state. 



Oauses.-^i may arise from whatever will produce in- 

 flammation of the bone, or arrests or suspends its nourish- 

 ment. It is a frequent sequel of fracture of the ribs, 

 sometimes from neglect or mismanagement of pole-evil, or 

 fistula of the withers ; in cattle, sometimes from " foul of 

 the foot." Whatever destroys the periosteum may produce 

 caries. 



Symptoms. — The surrounding tissues are swollen ; there is 

 an opening into the diseased Ibone, from which acrid, bad- 

 smelling matter discharges, in which float speculse of disin- 

 tegrated bone. On examining the bone, it presents' a fungus 

 which readily bleeds when touched ; on pressing the finger 

 into it, sharp processes of bone are felt, which are the bone 

 breaking up. The bone is easily punctured vrith a probe or 

 knife. 



Treatment. — ^This, in most cases, is a very tedious affair. 



