294 DISEASES OF THE HOKSE. 



implement by a sporting owner, under the pretext of " improving his 

 breed ; " or the extra exertion of starting an inordinately heavy load ; 

 or an effort to recover his balance from a misstep ; or slipping upon 

 an icy surface ; or sliding with worn shoes upon a bad pavement, and 

 other kindred causes. And we can repeat here what we have before 

 said concerning bones, in respect to heredity as a cause. From our 

 own experience we know of equine families in which this condition 

 has been transmitted from generation to generation, and animals 

 otherwise of excellent conformation rendered valueless by the mis- 

 fortune of a congenital spavin. 



Symptoms. — The evil is one of the most serious character for other 

 reasons, among which may be specified the slowness of its develop-, 

 ment and the insidiousness of its growth. Certain indefinite phenom- 

 ena and alarming changes and incidents furnish usually the only 

 portents of approaching trouble. Among these signs may be men- 

 tioned a peculiar posture assumed by the patient while at rest, and 

 becoming at length so habitual that it can not fail to suggest the 

 action of some hidden disorder. The posture is due to the action of 

 the adductor muscles, the lower part of the leg being carried inward, 

 and the heel of the shoe resting on the toe of the opposite foot. Then 

 an unwillingness may be noticed in the animal to move from one side 

 of the stall to the other. When driven he will travel, but stiffly, and 

 with a sort of sidelong gait between the shafts, and after finishing his 

 task and resting again in his stall will pose with the toe pointing for- 

 ward, the heel raised, and the hock flexed. Some little heat and a 

 considerable amount of inflammation soon appear. The slight lame- 

 ness which appears vhen backing out of the stall ceases to be notice- 

 able after a short distance of travel. 



A minute examination of the hock may then reveal the existence of 

 a bony enlargement which may be detected just at the junction of the 

 hock and the cannon bone, on the inside and a little in front, and 

 tangible both to sight and touch. This enlargement, or bone spavin, 

 grows rapidly and persistently and soon acquires dimensions which 

 render it impossible to doubt any longer its existence or its nature. 

 Once established, its development continues under conditions of prog- 

 ress similar to those to which we have before alluded in speaking of 

 other like affections. The argument advanced by some that because 

 these bony deposits are frequently found on both hocks they are not 

 spavins is fallacious. If they are discovered on both hocks, it proves 

 merely that they are not confined to a single joint. 



The characteristic lameness of bone spavin, as it affects the motion 

 of the hock joint, presents two aspects. In one class of cases it is 

 most pronounced when the horse is cool, in the other when he is at 

 work. The first is characterized by the fact that when the animal 

 travels the toe first touches the ground, and the heel descends more 



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