252 THE EXTERIOR OF THE HORSE. 



account. of the degree of closing which its angle has attained, and also 

 because the extensor muscles of the canon are in a more favorable 

 position to contract with intensity. 



A small tibio-tarsal angle depends upon one of two causes : an 

 excessive obliquity either of the canon or of the tibia. In the first 

 case, a portion of the force is expended in raising the trunk upward 

 instead of propelling it forward. In the second case, the tibia, being 

 too much inclined and too much directed backward, cannot execute its 

 movements upon the femur with sufficient freedom, and limits the 

 gracefulness and velocity of the locomotion. 



The tibio-tarsal angle, according to our measurements, oscillates 

 about 156 to 160 degrees in the most beautifully constructed running- 

 horses. It is never 136 degrees, as affirmed by the partisans of the 

 theory of the parallelism of the segments, not even in the draught- 

 horse, in which the angle is smaller, and in which, in truth, its exami- 

 nation is of no importance. 



In this respect our observations are absolutely in accord with those 

 of our colleague, M. Laulanie". 



Diseases and Blemishes. The diseases of this region, few as they are, 

 are nevertheless capable of presenting characters of exceptional gravity. We 

 will cite : 



1st. "Wounds caused by kicks from other horses, received during work, out- 

 door exercise, or in the stable. These wounds generally appear on the internal and 

 the anterior faces of the tibia. They are less grave upon the external surface, 

 because here the bone, protected by the muscles, is less predisposed to fractures. 

 The intense lameness which accompanies these injuries usually prevents the 

 animal from working or being presentable for sale. 



2d. Osseous tumors, of about the size of a hen's egg, sometimes observed 

 on the internal faces of the two tibiae, deserve the greatest consideration on the 

 part of the buyer. Although their presence may be related to a simple external 

 violence, yet they are often the sign of a veritable callus, that is to say, of the 

 work of consolidation which has taken place at the point where the bone has 

 been fractured in consequence of more or less intense traumatisms. Experience 

 has demonstrated that incomplete fractures of the bone, imperfectly consolidated, 

 may be rendered complete under the influence of muscular contraction alone. 

 It is advisable, therefore, to defer the purchase of a horse which presents this 

 blemish. 



3d. Lastly, let us mention the lameness due to rupture of the tendon of 

 the flexor of the metatarsus. This tendon, an integrant part of the muscle 

 in question, extends from the inferior and external extremity of the femur to the 

 supero-anterior extremity of the canon ; it plays a most important mechanical 

 role, in so far as it establishes an intimate connection between the movements of 

 the metatarsus and those of the thigh. This tendinous cord, under the influence 

 of the energetic efforts made by the animals to free themselves from their bonds 

 when placed under such restraint as is used by the blacksmith in shoeing a vicious 



