30 LAMENESS OF THE HORSE 



the purpose of "'stretching" contracted deep digital flexor 

 tendons (tiexor pedis perforans) cannot be too strongly con- 

 demned. While the addition of an extension such as is ordinarily 

 employed to the toe of a shoe of this kind, prevents for a time, 

 frequent stumbling in such cases, the increased tensile strain 

 which is thus occasioned hastens further contraction and sub- 

 jects animals so shod to much unnecessary pain. 



AFFECTIONS OF NERVES. 



Because of their being protected by other structures, nerve 

 trunks, which supply muscles of locomotion, are not su])jeeted to 

 frequent injuries such as contusions. However, they do become 

 injured at times and the result is lameness, more or less severe. 



Lameness originating from nerve affection, may involve central 

 structures as, for example, the spinal cord, medulla oblongata 

 or parts of the brain. In making an examination of some lame 

 animals it is necessary to distinguish between cases of lameness 

 that are of central origin and marked by incoordination of move- 

 ment, and disturbances caused by other affections. Tetanus in 

 its incipiency should not be confused with laminitis involving 

 all four feet, or with certain forms of pleuritis, when careful ex- 

 amination is made, yet, in a way, to one not trained, the clinical 

 symptoms are similar. 



Disturbances of nerve function are caused in a variety of ways. 

 It is not within the scope of this work to discuss central nervous 

 disturbances caused hy ingestion of mouldy provender, or dis- 

 turbances of the brain or cord occasioned by infectious diseases, 

 but mention of the existence of such conditions is appropriate. 



By direct injury the result of lilows, certain nerves are in- 

 jured and muscles supplied by such nerves are rendered inactive. 

 Depending upon the nature and extent of an injury thus in- 

 flicted, so the manner in which the affection is manifested varies. 

 The suprascapular nerve is rather frequently injured causing 

 partial or complete loss of function of the structures supplied 

 by this nerve, and abduction of the scapulohumeral joint nat- 

 urally results. 



In some cases of dystocia tbe obturator ner\'e, (or nerves, if 

 the involvement is bilateral), becomes injured by being caught 



