Jan. 20, 1923 
Carbon Tetrachlorid as an Anthelmintic 
179 
The carbon tetrachlorid in the smaller dose removed the few ascarids 
present, suggesting that this drug is perhaps as effective as carbon bisul- 
phid against these worms. 
In the doses used, carbon tetrachlorid killed all the Strongylus present 
in the two horses. This efficacy is in line with the 100 per cent efficacy 
this drug displays against other bloodsucking worms, such as hookworms 
in the dog and others we shall mention in this paper. That this drug is 
able to kill these worms in the large intestine of the horse is apparently 
due in part to the low solubility and relatively slight volatility of the 
drug which enable it to reach the large intestine in quantities sufficient 
to kill the worms, and this should also be correlated with the fact that 
this drug does not depress the unstriated musculature of the digestive 
tract and stop peristalsis. 
While the carbon tetrachlorid removed large numbers of cylicostomes, 
it also left large numbers. It appears to be inferior to chenopodium 
for the removal of these worms. 
In the paper in question (15), additional tests on horses, with mix¬ 
tures of carbon tetrachlorid and carbon bisulphid were reported. The 
tests indicate that the mixture is not a very useful one. We may state 
briefly that for removing the bots and worms from the stomach and 
small intestine, carbon bisulphid is the drug of choice, removing all bots 
and ascarids in almost all cases when given in doses of 6 drams in hard 
capsules to animals properly fasted. In our opinion it will probably 
kill specimens of Habronema not protected by the mucosa or in some 
other manner. For the removal of worms from the large intestine, 
chenopodium is the drug of choice, removing practically all Strongylus, 
cylicostomes and related strongyles, and the pinworms, when given in 
doses of about 4 to 5 drams to animals properly fasted. These two 
drugs supplement each other in eliminating the bots and worms from the 
digestive tract of the horse. Carbon tetrachlorid appears to be quite 
effective in removing ascarids and Strongylus, but to eliminate practically 
all the gastrointestinal parasites noted above it would need to be sup¬ 
plemented by carbon bisulphid to remove the bots and chenopodium to 
remove the cylicostomes and pinworms, whereas carbon bisulphid and 
chenopodium alone are sufficient. It does not therefore appear that car¬ 
bon tetrachlorid can be used for general purposes in removing worms 
from horses, though it might be the drug of choice in some cases for the 
specific purpose of removing ascarids or Strongylus or both. It is the 
best single drug of the three, apparently, since it removes the ascarids 
and Strongylus and removes some bots and cylicostomes. 
We have as yet too little information to permit of definite statements* 
as to the toxicity of carbon tetrachlorid for horses. The horse given 
50 cc. weighed about 900 pounds (409 kilos), the drug being given at a 
dose rate of slightly over 0.12 cc. per kilo. This horse, an old and weak 
animal, died on the fifth day after treatment and showed a number of 
chronic pathological conditions which could not be attributed to the drug. 
Since carbon bisulphid in 3 doses of 3 fluid drams each, a total of 9 fluid 
drams or about 35 cc., will occasionally kill old or weak animals, the only 
warranted assumption is that carbon tetrachlorid is probably safer than 
carbon bisulphid, the lethal dose rate per kilo being relatively low for 
both drugs and low for carbon tetrachlorid as compared with the lethal 
dose rate in the case of such animals as carnivores and poultry. 
