LAMENESS : ITS CAUSES AND TEEATMENT. 819 



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 th« caimon 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 

 renders 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 

 slowly, the motion of flexion at the hock taking place stiffly, and 

 accompanied with a dropping of the hip on the opposite side. In the 

 other case the peculiarity is that the lameness increases as the horse 

 travels ; that when he stops he seeks to favor the lame leg, and when 

 he resumes his work soon after he steps much on his toe, as in the 

 first variety. 



As with sidebones, though for a somewhat different reason, the 

 dimensions of the spavin and the degree of the lameness do not seem 

 to bear any determinate relation, the most pronounced symptoms at 

 times accompanying a very diminutive growth. The distinction 

 between the two varieties of cool and warm, however, may easily be 

 determined by remembering the fact that in most cases the first, or 

 cool, is due to a simple exostosis, while the second is generally con- 

 nected with disease of the articulation, such as ulceration of the 

 articular surface — a condition which, as we proceed further, will 

 receive our attention when we reach the subject of stringhalt. 



An excellent test for spavin lameness, which may be. readily 

 applied, consists in lifting the affected leg from the ground for one 

 or two minutes and holding the foot high so as to flex all the joints. 

 An assistant, with the halter strap in his hand, quickly starts the 

 animal off in a trot, when, if the hock joint is affected, the lameness 

 will be so greatly intensified as to lead readily to a diagnosis. 



Prognosis. — ^Having thus fully considered the history of bone 

 spavin, we are prepared to give due weight to the reasons that exist 

 for the adverse prognosis which we must usually feel compelled to 

 pronoimce when encountering it in practice, as well as to realize the 

 importance of early discovery. It is but seldom, Jiowever, that the 

 necessary advantage of this early knowledge can be obtained, and 



