UNSOUNDNESS 243 



These necessarily cause lameness. Others affect the extremity 

 or the shaft of the bones without involving the articulation. 

 Some are due to injury, others are of rachitic origin (rickets), 

 and due to faulty nutrition resulting in poor quality of bone. 



Ringbones are usually much more serious forms of unsound- 

 ness than splints, as they are more apt to be permanent in effect, 

 and even if the soreness be relieved, there is likely to be a me- 

 chanical lameness because of a stiffened joint. This unsound- 

 ness and the lameness resulting from it are very easily detected 

 in plain cases. 



Sidebones. — A sidebone is an abnormal condition of the lat- 

 eral cartilage — most common on the external cartilages of the 

 front feet — characterized by firmness under pressure and some- 



Fig. 84. — Sidebones. (M. H. B.) 



Due to an inflammation and ossification of the lateral cartilages : 1, nor- 

 mal os pedis; 2, 3, 4, varying types of sidebones. 



times enlargement. These cartilages are normally quite elastic. 

 The firmness is due primarily to a deposit of lime, a process of 

 ossification, i.e., bone formation — in the cartilage structure. 

 Sidebones are detected as bonelike structures which appear above 

 the crown of the hoof at the quarter and just beneath the skin 

 on either side. They may or may not cause lameness during 

 the period of inflammation and hardening. In some cases the 

 lameness is persistent. Other cases are very slow and mild and 

 no lameness is noticed. 



Spavin. — Bone spavin is one of the most serious forms of 

 unsoundness. This is a disease of the tarsal bones at the lower, 

 inner, front portion of the hock. There is usually something 

 of an exostosis, varying from very small size, commonly called 

 by horsemen a "jack," to very large size which every one rec- 

 ognizes as bone spavin. 



There is another form of bone spavin in which there is a 

 slight or no external development. In this form there is disease 



