364 BONE SPAVIN. 



cipally on the shank-bone, and in a slight degree on the outer splint-bone. The 

 middle wedge-bone, /j rests entirely upon the shank-bone, and the smaller 

 wedge-bone presses (not seen in the cut) in a very slight degree on the shank- 

 ibone, but principally or almost entirely on the inner splint-bone. Then the 

 splint-bones sustain a very unequal degree of concussion and weight. Not only 

 is the inner one placed more under the body and nearer the centre of gravity, 

 but it has almost the whole of the weight and concussion communicated to the 

 smaller cuneiform bone carried on to it. It is not, therefore, to be wondered at 

 that, in the violent action of this joint in galloping, leaping, heavy draught, and 

 especially in young horses, and before the limbs have become properly knit, 

 the inner splint-bone, or its ligaments, or the substance which connects it with 

 the shank-bone, should suffer material injury. 



The smith increases the tendency to 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 being considerably 

 raised from the ground. It is not unusual to see whole teams of horses 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 places an unequal strain on the ligaments of the joints, and particularly of 

 the hock-joint, and increases the tendency to spavin. 



The weight and concussion thus thrown on the inner splint-bone produce 

 inflammation of the cartilaginous substance that unites it to the shank-bone. 

 In consequence of it, 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 greatest 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 generally appears 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 357. 

 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, commonly, the disease commences on the precise 

 spot that has been described. 



While spavin is forming there is always lameness, and that frequently to 

 a very great degree : but when the membrane of the bone has accommodated 

 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. It is well known to horsemen, that many a hunter, with spavin 

 that would cause his rejection by a veterinary surgeon, stands his work with- 

 out lameness. The explanation is this ; there is no reason why an old bony 

 tumour on the outside of any of the bones of the hock, free from connexion with 

 the next bone, and from any tendon, should be at all injurious; as, for instance, 

 one immediately under e or/", p. 361 : but from the complicated nature of the 

 hock, it is difficult, if not impossible, to be quite sure of the place, or extent, 

 from inspection, of the tumour, and, besides, the disposition to throw out bone 

 covered by the tumour, may continue and extend to the joint. The surgeon, 

 therefore, cannot be perfectly safe in pronouncing a bone spavin to be of no 

 consequence. Horses with exceedingly large spavins are often seen that are 

 only slightly lame, or that merely have a stiffness in their gait at first starting, 

 but which gradually goes off after a little motion ; while others, with the bony 

 tumour comparatively small, have the lameness so great as to destroy the use- 

 fulness of the horse. There is always this peculiarity in the lameness of 



