STRYCHNINE SULPHATE 403 



appear sometimes extremely susceptible to strychnine, and 

 it is therefore advisable to begin with a minimum dose 

 (gi"- V120) in small animals. 



The dose of one grain should not be ordinarily exceeded 

 in the case of horses, as one and one-half grains proved 

 fatal in an exceptional case. If animals are depressed by 

 disease or shock, they will often bear much larger doses than 

 could ordinarily be administered with safety. 



Action External. — Strychnine is a powerful antiseptic, 

 but is of no practical value on account of its poisonous prop- 

 erties. Brucine is a local anaesthetic. 



Action Internal. — Digestive Tract. — Strychnine and 

 nux vomica act as bitter stomachics in increasing vascularity, 

 appetite, gastric secretion and motion. In addition to this 

 they improve the local tone of the alimentary canal; prob- 

 ably by exciting the various spinal centres. Strychnine also 

 stimulates the intestinal muscular tunic and therefore in- 

 creases peristaltic action. 



Circulation. — Experiments on animals show that the 

 chief action of strychnine on the circulation consists in stim- 

 ulation of the vasomotor centres with increase of blood pres- 

 sure. Clinically, however, strychnine appears to accelerate 

 and strengthen the heart-beat and this is thought to result 

 from excitation of the cardiac ganglia and muscle. In pois- 

 oning, blood tension is still further enhanced through as- 

 phyxia and muscular movements occasioned by convulsions. 



^Nervous System and Muscles. — The effect of strych- 

 nine, which stands preeminent before all others, consists in 

 the production of greatly exaggerated reflex action. Under 

 its influence slight sensory stimuli result in the most marked 

 and uncontrollable motor impulses (convulsions). It is 

 proved also that afferent impulses must reach the cord 

 through the sensory tract for convulsions to occur. Section 



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