288 THE HIND LEGS. 



ment. It must be considered as decided unsoundness. In a horse for slow draught, 

 it is scarcely worth while even to attack it. And in one destined to more rapid action, 

 the probability of a relapse should not be forgotten, when the chances of success and 

 the exnenses of treatment are calculated. 



The cause of the disease — the enlarged mucous capsule — lies deep, and is with 

 difficulty operated upon. Uniform pressure would sometimes cause the absorption 

 of the fluid contained in cysts or bags like these, but in a joint of such extensive 

 motion as the hock, it is difficult, or almost impossible, to confine the pressure on the 

 precise spot at which it is required. Could it be made to bear on the enlarged bag, 

 it would likewise press on the vein, and to a greater degree hinder the passage of the 

 blood, and increase the dilatation below the obstruction. The old and absurd method 

 of passing a ligature above and below the enlarged portion of the vein, and then dis- 

 secting out the tumour, is not, in the advanced stage of veterinary science, practised 

 by any surgeon who regards his reputation. The only method of relief which holds 

 out any promise even of temporary success, is exciting considerable inflammation on 

 the skin, and thus rousing the deeper-seated absorbents to carry away the fluid effused 

 in the enlarged bag. For this purpose, blisters or firing may be tried : but in the 

 majority of cases, the disease will bid defiance to all appliances, or will return and 

 baffle our hopes when we had seemed to be accomplishing our ol)ject. 



A horse with bog spavin will do for ordinary work. He may draw in a cart, or 

 trot fairly in a lighter carriage, with little detriment to his utility ; but he will never 

 do for hard or rapid work. 



BONE SPAVIN. 



A still more formidable disease ranks under the name of Spavin, and is an affec- 

 tion of the bones of the hock-joint. It has been stated that the bones of the leg, the 

 shank-bone, g, p. 286, and the two small splint-bones behind, h, support the lower 

 layer of the bones of the hock. The cube-bone, d, rests principally on the shank- 

 bone, and in a slight degree on the outer splint-bone. The middle wedge-bone, /, 

 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-bone, 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, sliould 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 inflam- 

 mation of the cartilaginous substance that unites it to the shank-bone. In conse- 

 quence of it, the cartilage is absorbed, and bone deposited ; the union between the 

 splint-bone and the shank becomes bony, instead of cartilaginous; ihe 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 tlie greatest weiojit and con- 

 cussion 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 di^positi^d, 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, p. 283. This is called bone spavin. Inflammation of tlu; 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 pre- 

 cise spot that has been described. 



