398 VEGETABLE DRUGS 



In accordance with the foregoing figures, the dose for the 



Horse weighing 1,000 lbs. is .045-.09 (gr.%-1%) 



Dog weighing 100 lbs. is .0045 (gr.1/13) 



Dog weighing 50 lbs. is .00225 (gr.1/26) 



Dog weighing 25 lbs., is .00112 (gr.1/52) 



Dog weighing 10 lbs. is .00045 (gr.1/133) 



The foregoing table refers to oral administration ; the subcutaneous 

 dose of strychnine is but one-half of the dose by the mouth. 



Moreover, these doses may be given every three hours without pro- 

 ducing poison by their cumulative action. Notwithstanding the fore- 

 going figures, caution should be exercised in prescribing strychnine to 

 dogs, as these animals appear sometimes extremely susceptible to strych- 

 nine, and it is therefore advisable to begin with a minimum dose (gr. 

 1/200) 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, poison, 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 properties. Brucine is a local 

 anesthetic. 



Action Internal. — Digestive Tract. — Strychnine and nux vomica act 

 as bitter stomachics in increasing appetite, gastric secretion and motion. 

 In addition to this they improve the local tone of the alimentary canal; 

 probably by exciting the various S23inal centres. Strychnine also stimu- 

 lates the intestinal muscular tunic and therefore increases peristaltic 

 action. 



Circulation. — Experiments on animals show that the chief action of 

 strychnine on the circulation consists in stimulation of the vasomotor 

 centres with slight increase of blood pressure. Clinically, however, 

 strychnine appears to accelerate and strengthen the heart-beat and this is 

 thought to result from excitation of the cardiac muscle. There is, how- 

 ever, no experimental evidence to show that medicinal doses of strychnine 

 influence directly the mammalian heart (Cushny). Experimentally it has 

 been found that either the vagus or accelerator centres may be sensitized, 

 so that either slowing or quickening of the mammalian heart may result. 

 Also that strychnine actually depresses the perfused heart muscle of the 

 frog. The heart is accelerated by muscular activity in convulsions. 

 Very large doses slow and weaken the heart. In poisoning, blood tension 

 is still further enhanced through asphyxia and muscular movements oc- 

 casioned by convulsions forcing the blood out of the abdomen. 



Nervous System and Muscles. — The effect of strychnine, which 

 stands preeminent before all others, consists in the production of greatly 

 exaggerated reflex action. Under its influence slight sensory stimuli re- 

 sult 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 of the spinal cord from 



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