COCAINE HYDBOCHLORIDE 435 



cocaine into the plantar nerve trunk, on either side of the 

 leg and a little above the point of selection for plantar neu- 

 rectomy, will often completely abolish sensation in the foot. 

 This fact may be determined by pricking the soft parts 

 above the hoof. If there is complete anaesthesia of the foot, 

 and the seat of lameness be situated therein, the horse will 

 go sound while the anaesthesia lasts. This method may be 

 taken advantage of in the diagnosis of localized lameness 

 elsewhere. If cocaine is injected over an area (suspected to 

 be the cause of lameness), and the animal goes sound while 

 the cocaine anaesthesia lasts, the site of lameness becomes 

 certain. 



It has been discovered that injections of powerful 

 cocaine solutions into a sensory nerve trunk will paralyze its 

 sensibility throughout its peripheral distribution (regional 

 anaesthesia). When ligation of a limb, or part, can be 

 secured between the operative field and the heart, the 

 anaesthetic action of cocaine is more profound and toxic 

 symptoms are less liable to occur, since the drug is drained 

 away in the blood during the operation. Many operations 

 can be performed under cocaine, as neurectomy, firing, 

 tenotomy, etc., without casting the horse. In using cocaine 

 for the removal of tumors, or opening of abscess, the solu- 

 tion is injected at several points in a circle about the base 

 of the tumor or abscess, and not in the inflamed tissue of 

 the latter. Following the first injection, the succeeding 

 applications may be made painless by inserting the needle 

 within the area made ansesthetic' by the previous injection 

 (circumferential anaesthesia). 



The amount of cocaine solution to be injected is of 

 importance. This depends upon the strength of the solu- 

 tion, the weight and species of the animal, and the seat of 

 application. A solution stronger than 4 per cent, is irritat- 

 ing to the eye. The stronger cocaine solutions (5 to 10 per 

 cent.) are more powerful paralyzants to the sensory nerves, 

 and are advisable when they can be used with safety, but a 

 4 or 2 per cent., or even a much weaker solution, will ordin- 



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