BONE-SPAVIN I I 7 



upon the other can be prevented by adding a calkin on 

 the outer heel of the shoe, which consists in the 

 extremity of the shoe being bent, elevating the 

 outer heel considerably above the ground, and thus 

 the ligaments of the joints are subjected to an unequal 

 strain, and especially those of the hock, which in- 

 creases the tendency to spavin. 



It is this which induces, in the first instance, inflam- 

 mation of the cartilaginous union of the shank-bone, 

 and this cartilage is absorbed, and a secretion of bony 

 substance deposited in its stead ; consequently the 

 elastic action between them is terminated, and the 

 splint inside the hind leg formed, and has the appear- 

 ance of a tumour, when the head of the splint-bone 

 is united with the shank, and always in front of that 

 junction, as exhibited in Plate vn, fig. 3, c. 



Lameness generally accompanies spavin during its 

 growth, but when the periosteum or membrane of the 

 bone has been stretched, and taken the form of the 

 bony enlargement, then the pain subsides, and with it 

 the lameness. Many instances occur of horses with 

 large spavins, and yet they are not much affected with 

 lameness ; sometimes having merely a stiffness of the 

 joint, which is not apparent after the animal has had a 

 little exercise. And, on the contrary, there are in- 

 stances in which the bony deposit is very small, and 

 yet the horse is very lame, so much so as to render 

 him comparatively useless. In all such cases it will 

 be found that the growth, large or small, or entirely 

 awanting, is associated with ulcerative disease of at 

 least two of the small bones of the hock, and removal 

 of the cartilage which clothes and protects their glid- 

 ing surfaces. The worst form of spavin (or so-called 

 occult spavin) is characterised by an absence of bony 

 growth. It must therefore be evident that we ought 



