270 THE HORSE. 



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

 ?uttin<T, 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 con- 

 siderably 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 hearing, 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 substance 

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

 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 liga- 

 ments of any one of the small bones of the hock, proceeding to bony tumour 

 would equally class under the name of spavin; but, with very few excep- 

 tions, the disease commences on the precise spot we have described. 



Wiien 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 which 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, f, page 266, for these are nearest to its original 

 seat. They are capable of slight motion, and share 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 b, 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 inany 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 tlie cube-bones on the other side, 

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

 or parts of the joint, in which the motion is small; but when it extei^la 



