

EEMOVAL OF THOBN-HEADED WORMS FEOM SWINE 9 



DISCUSSION 



CARBON TETRACHLORIDE 



Carbon tetrachloride in these tests showed some efficacy against 

 thorn-headed worms. In doses of 25 c. c. in 75 c. c. of castor oil it 

 removed 11.8 per cent of the thornheads present in 15 pigs of an 

 average weight of 125 pounds. In doses of 32 c. c. in 96 c. c. of 

 castor oil, carbon tetrachloride removed 9.6 per cent of the thorn- 

 heads present in 12 pigs weighing from 100 to 125 pounds each. The 

 drug administered in a dose of 45 c. c. in 45 c. c. of castor oil removed 

 all the thornheads from one pig. Carbon tetrachloride in doses of 

 30 c. c. combined with 15 c. c. of a 1 per cent solution of nicotine 

 sulphate, administered to 5 pigs of an average weight of 143 pounds. 

 was 100 per cent effective against thornheads. It is apparent from 

 these tests that the drug must be given in relatively high doses in 

 order to be effective. Hall and Shillinger (4) , in 1923, stated that the 

 therapeutic dose rate of carbon tetrachloride for swine is 0.6 c. c. per 

 kilogram of body weight, while the minimum lethal dose rate is 

 between 1.66 and 3 c. c. per kilo. The factor of safety, therefore, is 

 between 2.66 and 5 (i. e., the minimum lethal dose is 2.66 to 5 

 times the therapeutic dose), a very small margin as compared with 

 a relatively high factor of safety for poultry and some other animals. 

 They conclude that " swine are, therefore, rather poor subjects for 

 treatment with carbon tetrachloride or other drugs acting on the 

 liver * * * a fact probably associated, among other things, with 

 the prevalence of parasitic hepatic cirrhosis in swine." This obser- 

 vation is borne out in these experiments when the drug was combined 

 with a 1 per cent nicotine -sulphate solution, the treatment resulting 

 in the condemnation of all the pigs for icterus and the presence of 

 fatty degeneration and central necrosis in the livers of these animals. 

 The weight of the pig receiving 45 c. c. of the drug was not deter- 

 mined, but the average weight of the pigs receiving 30 c. c. of the 

 drug combined with a 1 per cent nicotine-sulphate solution was 143 

 pounds or 65 kilos. The dose rate of the carbon tetrachloride in this 

 instance, therefore, was 0.46 c. c. per kilogram or 27.7 per cent of the 

 minimum lethal dose of 1.66 c. c. per kilogram, taking the lowest 

 figure of Hall and Shillinger. This does not leave a wide margin 

 of safety for the drug, and it would not seem that carbon tetra- 

 chloride could be generally recommended for use at such a dose rate. 

 It would appear, therefore, that while carbon tetrachloride possesses 

 a fair degree of efficacy against thorn-headed worms, the margin of 

 safety is so small that its general use might be hazardous. The com- 

 bination with nicotine looks promising and deserves further test. 



EXTRACT OF MALE FERN 



Ethereal extract of male fern given to 12 pigs of an average 

 weight of 65 pounds each, in doses of 4 c c. followed by 30 c. c. 

 of castor oil, failed to remove any of the thornheads or ascarids 

 present. Male fern is primarily a taeniacide and it is not to be 

 expected that it would show any great efficacy against roundworms. 

 As the zoological affinities of the acanthocephalids are not well 

 established, there was the possibility that they might respond to 

 treatments for tapeworms as well as to those for nematodes, or 

 perhaps better. 



