NEUROTOMY, NEURECTOMY, UNNERVING 161 



NEUROTOMY, NEURECTOMY, UNNERVING 



The operation known by the above terms is undertaken with the object 

 of depriving some part of an animal of sensation when affected with an 

 incurable disease. It is resorted to in cases of navicular disease, of side- 

 bone, ring-bone, and other forms of lameness of a chronic and painful 

 character, more especially in the region of the feet. 



Unnerving, although always effective in depriving the part of sensation, 

 is attended with a varying measure of success, largely dependent upon the 

 judgment of the surgeon. If undertaken upon a subject of navicular dis- 

 ease, for instance, it is important that the foot shall have sufficient strength 

 of horn to receive the nails, without risk of binding or pricking in the course 

 of shoeing. When deprived of sensation, injuries of this kind are not 

 recognized by the horse, and he continues to use the diseased and unfeeling 

 foot without that care which he would otherwise take of it, and without 

 showing any signs of lameness. The presence of corns, which may fester 

 in a foot deprived of sensation, is another element of danger, since in the 

 absence of pain and lameness it is liable to pass unnoticed, until irreparable 

 mischief is wrought. It is, however, an error to suppose that reparative 

 power is lost when the purely sensory nerves are divided. If a pricked 

 foot or one with a festered corn is detected before serious inflammatory 

 changes have taken place, recovery may be looked for, if judiciously treated. 



Neurectomy, if performed on suitable subjects, is undoubtedly a valu- 

 able operation, and may add two or three years or more to the usefulness- 

 of an animal. 



Methods Of Operation.- The operation is distinguished topographi- 

 cally as the high operation and the low operation. These terms are some- 

 what confusing to the beginner, as there is another neurectomy frequently 

 performed, but adopted much later. It is called median, and is the highest 

 on the limb, the median nerve being situated on the inner aspect of the 

 forearm as shown at Fig. 502. For the present the old nomenclature must 

 be retained. The high operation consists in division and removal of a 

 portion of the trunk of the plantar nerve immediately above the fet- 

 lock. Here it runs a little to the front of the border of the back tendons 

 (fig. 502), and, being immediately beneath the skin, affords the surgeon 

 facilities for division without the risk of injuring other structures. It is 

 rather more superficially placed on the outside, and as its bifurcation takes 

 place somewhat lower down than on the inner side, the incision in the skin 

 may be made a little farther down the limb in the former than the latter. 

 It is usual to divide both nerves, though not always necessary, as, for 



VOL. ill. 76 



