110 VETERINAEY TOXICOLOGY 



Action and Symptoms. — Strychnine acts as a powerful 

 stimulant to the central motor cells, and thus affects chiefly 

 the spinal cord. The reflex irritability is greatly increased, 

 probably by reason of a reduced resistance to the passage 

 of peripheral stimuli along the sensory nerves. When the 

 peripheral nerve-endings are paralysed by cocaine, injec- 

 tion of strychnine fails to produce the tetanic convulsions, 

 and severance of the posterior roots of the spinal nerves in 

 frogs has been shown by Claude Bernard to inhibit the 

 convulsions, save when the nerve ending is stimulated. 

 In a frog in which the anterior portion only is effused with 

 strychnine solution, stimulation of the hind extremities is 

 followed by ordinary reflexes, but stimulation of the anterior 

 extremities leads to general tetanic convulsion. After the 

 intense stimulation depression and paralysis follow. 



Under the influence of strychnine an exceedingly slight 

 iexternal stimulus, such as a current of air, induces a normal 

 reflex, immediately followed by the characteristic general 

 tetanic spasms, during which the back is curved (opistho- 

 tonus), respiration arrested, and the muscles are tense. 

 Death results from asphyxiation ; usually the respiration 

 ceases after two or three spasms. 



Animals tend to avoid light, and display marked hyperes- 

 thesia. During the spasms the rigidity of the extended 

 limbs is so great that a small animal may be lifted in a 

 perfectly straight position by one extremity. 



In horses symptoms set in some hours after such doses 

 as 5 to 6 grains, and involve an accelerated pulse, laboured 

 breathing, abdominal pain, sensitiveness to touch, and 

 tetanic spasms. From 1 to 2 ounces of nux vomica are 

 required to poison the horse. 



Macqueen* observed strychnine symptoms in the treat- 

 ment of paralysis in the horse by doses of strychnine, 

 increasing from 1 grain to 5 grains twice daily. Twitching 

 of the superficial muscles is a preliminary warning. Within 

 about twenty minutes after a further dose the horse rears 

 falls, and makes galloping movements, so that it moves 

 * Private communication. 



