270 THE HORSE. 



this, by his injudicious management of the feet. It is a common notion, 

 that cutting-, and wounds in the feet, from one foot treading on the other, 

 are prevented by putting on a shoe with a calkin on the outer heel, that is, 

 the extremity of the heel of the shoe being bent, and thus the outer heel 

 considerably raised from the ground. It is not unusual to see whole 

 teams of horses, and that all the year round, with the outer heel of the 

 hind foot considerably raised above the other. This unequal bearing, or 

 distribution of the weight, cannot fail of being injurious; it will place an 

 unequal strain on the ligaments of the joints, and particularly of the hock- 

 joint, and increase the tendency to spavin. 



The weight and concussion which are thus thrown on the inner splint- 

 bone produce, in the first place, inflammation of the cartilaginous sub- 

 stance which unites it to the shank-bone. The consequence of this is, 

 that the cartilage is absorbed, and bone deposited ; — the union between 

 the splint-bone and the shank becomes bony instead of cartilaginous ; — 

 the degree of elastic action between them is destroyed, and there is formed 

 a splint of the hind-leg. This is uniformly on the inside of the hind- 

 leg, because the greater weight and concussion are thrown on the inner 

 splint-bones. As in the fore-leg, the disposition to form bony matter 

 having commenced, and the cause which produced it continuing to act, 

 bone continues to be deposited, and it appears generally in the form of a 

 tumour, where the head of the splint-bone is united with the shank, and 

 in front of that union. It is seen at c, page 262. This is called bone- 

 spavin. Inflammation of the ligaments of any of the small bones of the 

 hock, proceeding to bony tumour, would equally class under the name of 

 spavin, but, with very few exceptions, the disease commences on the pre- 

 cise spot we have described. 



When spavin is forming there is always lameness, and that frequently 

 to a very great degree ; but when the membrane of the bone has accom- 

 modated itself to the tumour that extended it, the lameness subsides, or 

 disappears, or depends upon the degree in which the bony deposit interferes 

 with the motion of the joint. We often see horses with exceedingly large 

 spavins, that are only slightly lame, or that merely have a stiffness in their 

 gait at first starting, and that gradually goes off after a little motion ; and 

 we meet with others with the bony tumour comparatively small, yet the 

 lameness so great as to destroy the usefulness of the horse. There is 

 always this peculiarity in the lameness of spavin, that it abates, and some- 

 times disappears, on exercise ; and therefore, a horse, with regard to 

 which there is any suspicion of spavin, should be examined, when it first 

 in the morning is taken from the stable. 



If the spavin continues to increase, the bony deposit first spreads over 

 the lower wedge bones, /*, page 266, for these are nearest to its original 

 seat. They are capable of slight motion, and shape in every action of the 

 joint, but their principal design was to obviate concussion. The chief 

 motion of the joint, and that compared with which the motion of the others 

 is scarcely to be regarded, is confined to the tibia a, and the astragalus 6, and 

 therefore, stiffness rather than lameness may accompany spavin, even 

 when it is beginning to affect the small bones of the joint. Hence, too, we 

 see the advantage of these bones having each its separate ligaments and 

 membranes, and constituting so many joints, since injury may happen to 

 some of them, without the effect being propagated to the rest. When the 

 bony deposit continues to enlarge, and takes in the second layer of bones, the 

 larger wedge bones e, and even spreads to the cube bones on the other side, 

 even then the lameness may not be excessive, because these two are joints, 

 or parts of the joint, in which the motion is small ; but when it extends 



