68 



Journal of Agriculture. 



[8 Feb., 1907. 



female should be in an effective stage of "season." As many as half-a-dozen 

 mares are stated to have been successfullv impregnated with semen with- 

 drawn from a mare after one service. 



Fij^'. 7. — (a) Impregnation syringe, {b) Withdrawing fluid from vagina, {c) Injecting 



fluid into womb. 



Neurotomy and Neurectomy (Unnerving). 



Neurotomy is the operation of cutting a nerve, and Neurectomy the 

 cutting out or removal of a portion of a nerve. Both operations are per- 

 formed on horses for the purpose of depriving the part supplied bv such 

 nerve of sensation, and so relieving pain and consequent lameness. To 

 this end neurotomy is Lne least effective, because the cut ends of the nerve 

 frequently grow together, and sensation is renewed. Neurectomy is 

 therefore most frequently performed. Its performance is almost solely 

 confined to certain nerves of the fore limb, for the removal of persistent 

 lameness associated with such diseases as ringbone, sidebone, and navicular 

 disease. The usual seat of the operation is either above or below the fet- 

 lock, along the course of the plantar or digital nerves respectively. The 

 former is known as high neurectomy, and the latter as low neurectomy. 

 The median nerve above the knee and the anterior tibial nerve above the 

 hock are also sometimes operated upon. (See Figs. 8 and 9.) Before 

 describing the operation, it should be mentioned that in high neurectomy, 

 if it is desired to completely remove the perception of pain in the region 

 below, it is necessary to operate on both the internal and external plantar 

 nerves, because of the fact that recurrent nerve filaments from the one 

 n^rve also serve the parts supplied by the other. 



Anatomical knowledge of the course of the nerves is an essential to 

 success in this operation. The reminder may be here given that the 

 plantar nerve, as it passes downwards towards the fetlock joint, is accom- 

 panied by the artery and vein. The three lie side by side, the vein being in 

 front, the artery in the middle, and the nerve most posteriorly. The 

 word " van," being composed of the initial letters of the three structures, 



