476 HEALTH AND DISEASE 



DRUGS WHICH ACT UPON THE NERVOUS SYSTEM 



If the reader has studied the part of this work dealing with the dis- 

 tribution and function of tlie nerves, he will understand that the whole 

 animal machine depends upon them to keep its various organs working- 

 together in harmony and sympathy one with another. The question as 

 to what drugs act upon the nervous system can only be answered in a 

 limited sense. It is probable that no drug can act without its aid, but 

 there are special agents which experience and experiment have demon- 

 strated to have a particular and well-marked action on nervous tissue, and 

 to these we give the title which apjaears above. 



If we desire to affect a particular nerve or branch, we cannot select an 

 agent that will speed like an arrow to the spot indicated and aflect no 

 other, but we must seek to obtain the desired effect through the medium of 

 the blood. The agent will have to be taken into the circulation, and there 

 will ])e distributed over the nervous system in an equal degree. 



HYPNOTICS OR SOPORIFICS 



Drugs which conduce to sleep are called by the above names, and their 

 action upon man is fairly uniform except where some special idiosyncrasy 

 exists; but with regard to horses we are not so well informed. They are 

 light sleepers as a rule, and in health seldom repose for longer than four or 

 five hours. The nervous temperament of the animal does not permit him 

 to abandon himself to that complete oblivion which is a more or less 

 acquired habit by civilized man enjoying perfect security of life. Drugs 

 wdiich have a soothing influence upon the nervous system, and invite sleep 

 rather than compel it, are called by the above names, but those which over- 

 power the brain and master the inclinations are known as Narcotics. The 

 same agent may act as a gentle soporific in small doses and as a powerful 

 narcotic in large ones. Drugs which relieve pain conduce to sleep, the 

 anodyne effect of opium having been understood jjerhaps longer than that 

 of any other drug. 



Chloral Hydrate, although discovered by Liebig in 1832, did not 

 come into use in this country until quite thirty years later, and its value in 

 veterinary medicine was not ascertained until some years after the medical 

 profession had proved its efficiency as a therapeutic in human practice. 



It is extremely distasteful to horses owing to the hot burning sensation 

 it imparts to the mouth, and in a lesser degree to the skin also, while it 

 acts as a powerful irritant to abraded surfaces. 



