138 MANUAL OF MODERN FARRIERY. 



strain, and especially those of the hock, which increases the 

 tendency to spavin. 



It is this which induces in the first instance inflammation 

 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 appearance 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 7, fig. 3, c. 



Lameness universally accompanies spavin, 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. This, however, depends 

 upon the size of the spavin, and whether it interferes with 

 the motion of the joint. Many instances occur of horses 

 with large spavins, and yet they are not much afflicted 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 instances in 

 which the bony deposit is very small, and yet the horse is 

 very lame, so much so as to render him comparatively 

 useless. It must therefore be evident that we ought care- 

 fully to examine horses with spavin before they have had 

 exercise, and as soon as they have left the stable. 



Sometimes spavin continues to enlarge considerably, and 

 spreads over the lower wedge-bones, (plate 7, fig. 8, e.) in 

 consequence of these being nearest the original seat of the 

 enlargement. These bones are capable of a small degree 

 of motion, and participate in every action of the joint, but 

 their chief oflSce is to prevent concussion. The principal 

 motion of the joint is in the tibia, 5, and the astragalus, 

 Cy and consequently stiffness more than lameness may 



