Feb. 18. 1918 Efficacy of Some Anthelmintics 423 



THYMOL 



For worms in dogs. — Prior to the beginning of the great European 

 war, thymol was the classic remedy for hookworm in man, and it was 

 only after the war had made this drug practically unobtainable that 

 serious efforts were made to find a substitute for it. In a general way 

 it was regarded as a satisfactory drug, and we expected to find a fairly 

 high coefficient of efficacy for it in our experiments. 



In our first experiment thymol was administered at the rate of 130 

 mgm. per kilo of body weight, giving the thymol in capsules to 2 dogs 

 and in drench to 2 dogs ; in the latter case the thymol was dissolved in a 

 small amount of alcohol and this added to water to make a fine suspension. 

 After an interval of a half hour to an hour, calomel in doses of about 65 

 mgm. per 2.5 kilos of weight of dog was given. All dogs were fasted from 

 the previous day. 



As regards hookworms, thymol removed 15 out of a total of 114 worms 

 present, being entirely ineffective in the case of three dogs, two of which 

 received the thymol in capsule and one of which received it in aqueous 

 suspension. In one dog, however, it removed 15 out of 16 hookworms. 



In regard to ascarids, thymol removed nearly three-fourths of these 

 worms present, a very satisfactory showing considering that thymol is 

 not usually considered especially valuable as an ascaricide. It was not 

 efficacious when administered in aqueous suspension. Thymol also 

 exhibited some efficacy against whipworms and was very slightly ef- 

 fective for Dipylidium caninum. 



In the above experiment thymol showed a low degree of efficacy 

 against hookworms, the parasite for which it is usually prescribed, and 

 was more efficacious against whipworms and still more efficacious against 

 ascarids. In the experience of the writers a number of drugs were 

 found to be occasionally efficacious against whipworms, while at other 

 times they were decidedly inefficacious. This variation may perhaps 

 be explained as a matter of accident, depending on whether or not the 

 drug succeeds in penetrating to the cecum in its passage through the 

 alimentary tract. 



An objection to thymol at present is its cost and scarcity. 



In order to determine whether the low degree of efficacy displayed 

 against hookworms by thymol was due to the mode of administration, 

 the experiment was repeated. This time the animals were subjected to 

 preliminary purgation with Epsom salt, and the administration of 

 calomel after treatment was delayed for five to six hours. The thymol 

 was given in the same dosage, 130 mgm. per kilo of body weight, and was 

 given in aqueous suspension. 



Three dogs weighing 4 to 9.3 kilos were used for the experiment. They 

 were given Epsom salt at the rate of 3.7 mils for each 5 kilos of weight, 

 the day prior to the administration of the anthelmintic, and five to six 



