LAMENESS: ITS CAUSES AND TREATMENT. 319 
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 
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 
pronounce when encountering it in practice, as well as to realize the 
importance of early discovery. It is but seldom, however, that the 
necessary advantage of this early knowledge can be obtained, and 
