232 



THE EXTERIOR OF THE HORSE. 



" In this class," says H. Bouley/ " we even find horses whose 

 knees arch forward to such an extent, when they are standing still, 

 that we wonder how they manage to hold themselves up ; and never- 

 theless, even laboring under such an exaggerated form of this defect, 

 they never stumble when once they have been started. The reason of 

 it is that the remarkable attitude of these animals does not bespeak 

 any weakening in the powers of their extensor muscles, as it does in 

 the horse that has become knee-sprung through hard work and old age." 

 Custom alone enables us to distinguish true or acquired sprung 

 knees ; let us add that it is also revealed by the trembling of the knees 

 when the horse is in a resting posture, as well as by the habitual pres- 

 ence of hard or soft blemishes upon the inferior regions of the members. 

 If, contrary to what we have seen, the knee deviates towards the 

 back of the vertical axis (Fig. 69), it is termed effaced, 

 sunken, hollow, or sheep-knee. 



This defect, chara(;terized by a concavity of its ante- 

 rior face and a more distinct prominence of the supra- 

 carpal bone, has not, so far as we know, the importance, 

 as regards speed, which some would attach to it. It 

 necessitates, without doubt, a somewhat more extensive 

 contraction of the flexors of the metacarpus, to bring 

 that region into the attitude required by normal flexion, 

 whence a loss of time in the execution of the move- 

 ments. This loss of time and of muscular force, which 

 result from it, are insignificant and can hardly be appre- 

 ciated. Such a conformation is vicious, rather in so far 

 as it causes a continual tension of the posterior ligamentous 

 apparatus of the carpus and the check tendon of the 

 Fig. 69. perforans, a tension which tells likewise upon the lateral 

 ligaments and becomes further increased at every instant 

 of contact with the ground, when the animal is moving at great speed. 

 These excessive tractions, injuring the articular ligaments, will eventu- 

 ally bring about the formation of osseous deposits at the points of 

 their insertion upon the bones, or else a permanent induration of the 

 check tendon and the suspensory ligament of the fetlock. 



Considerations of a similar nature are applicable to a knee which 

 deviates to the inner side of the vertical axis, and which is styled 

 ox-knee, from its analogy to that of the animal whose name it bears 

 (Fig. 70). Very convex upon its internal face and concave externally, 



1 H. Bouley, Nouveau Dictiounaire pratique de medecine, de chirurgie et d'hygiene v6teri- 

 naires, t. viii. p. 201. 



