258 PRINCIPLES OF VETERINARY SCIENCE 



NICKING 



Under this term may be mentioned the operations"for correct- 

 ing curvature of the tail, and the prevention of the gripping of 

 the reins by the tail. The first operation is the simpler, and 

 consists in simply cutting across the levator or extensor muscles 

 of the side toward which the tail is curved. It is performed sub- 

 cutaneously under the control of the twitch and side-line. If 

 the operation is successful, the tail will be carried in a normal 

 manner after the wound heals. The operation to prevent grip- 

 ping the reins is more extensive, and usually requires that the 

 animal be thrown. It consists in dissecting out and removing 

 about 5 inches of the depressor muscles on each side of the in- 

 ferior surface of the tail. 



UNNERVING 



Unnerving is performed to relieve pain in a part, to prevent 

 lameness in a limb, or to stop motion, as in the "cribbing" 

 operation. The operation is technically termed neurotomy, and 

 consists in severing or actually removing a portion of a sensory 

 nerve. It should always be performed under either local or 

 general anesthesia for it is painful. 



Neurotomy should be the last resort for the relief of lameness. 

 When the part is deprived of sensation there is always danger of 

 breakdown in the limbs; besides, if an injury occurs, the animal 

 is not aware of it and serious results follow which may jeopardize 

 life. 



The commonly performed neurotomies are digital neurotomy, 

 which has for its object the relief of navicular lameness in cases 

 where plantar neurotomy is not deemed necessary or advisable; 

 plantar neurotomy, for the relief of navicular or ringbone lame- 

 ness, or other non-infectious, painful conditions below the fetlock; 

 median neurotomy, to relieve lameness due to disease of the fore 

 limb, so located that it cannot be overcome by plantar neurotomy; 

 sciatic and anterior tibial neurotomies, for the destruction of sen- 

 sation in the hock and parts distal thereto to relieve otherwise 

 incurable spavin lameness and diseases of the tendons. 



TENOTOMY 



The operation of tenotomy is the dividing of a tendon. It 

 is performed to lengthen a contracted tendon. It is valuable 



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