CHAPTER XXIII 



POISONS AND POISONING 



DEFINITIONS 



A poison is any substance that may cause or causes death when 

 applied externally, taken internally, or developed within the body. 



Toxicology is the scientific study of the actions, effects, and 

 antidotes of poisons. 



Antidotes are medicines employed to counteract poisons. 

 There are three different kinds depending on the way in which 

 they operate: Mechanical antidotes operate by removing the 

 poison from the body; examples are the various emetics and 

 cathartics. Chemical antidotes prevent poisoning by decom- 

 posing the poison or by changing it into a compound which is 

 not poisonous; examples are iron for arsenic and starch for iodin. 

 Physiologic antidotes produce an action which will counteract 

 the effect of the poison; an example is coffee as an antidote 

 against morphin. 



Poisoning is rare except from accidental causes, and then 

 almost always occurs from the ingestion of poisonous plants. 

 Malicious poisoning is usually attempted with either arsenic or 

 strychnin. When poisoning is suspected all other possible causes 

 should be looked for, as in many cases a careful search will show 

 that something else is actually responsible for the sickness. 



The diagnosis of poisoning requires a careful postmortem 

 examination and a chemical analysis of the stomach contents. 

 This is quite expensive as the services of a competent analytical 

 chemist are needed. When a poison is found there is no doubt 

 about the cause of death. 



There are three classes of poisons, viz.: (1) animal, e.g., 

 cantharides; (2) vegetable, e.g., loco weed; (3) mineral, e.g., 

 arsenic. 



ANIMAL POISONS 



Cantharides poisoning results from carelessness in applying 

 Spanish fly blister or carelessness in tying the animal to prevent 

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