Jan. 20,1923 
Carbon Tetrachlorid as an Anthelmintic 
173 
quite favorable, both as regards the efficacy of the drug against hookworms 
and as regards its safety. This is a matter of considerable interest and 
importance, since hookworms, mostly Uncinaria stenocephala y are very 
common in fur foxes raised in captivity, and because of the value of these 
animals, some of them being worth $900 to $2,000, or more, a pair, the 
loss of an individual animal is a serious matter. One fox raiser states 
in correspondence that in the last two years he has lost at least $50,000, 
mostly because of hookworms. This man has reported some interesting 
experiments on the administration of carbon tetrachlorid to foxes. 
In two cases a capsule containing 1.55 cc. of carbon tetrachlorid was 
pushed into the windpipe, causing death in 1 to 2 minutes. This, of 
course, is a matter of technic. 
In administering capsules to hundreds of dogs we have never pushed 
one into the windpipe. However, it is difficult to avoid this in foxes, 
since the capsules are given to adult foxes with a balling gun, a much 
less sensitive instrument than the fingers. Doctor Hanson tells us that 
capsules may be administered with the fingers to fox pups up to 6 weeks 
old. This would appear to be the safest and best mode of administration 
for fox pups. The fox raiser referred to above gave to 3 foxes, weighing 
about 15 pounds each, doses of about 18.6 cc. of carbon tetrachlorid 
by drench, a dose rate of approximately 2.7 cc. per kilo. All the ani¬ 
mals showed convulsions, probably as a result of inhalation intoxication, 
and 1 of them died, the other 2 recovering. A report on these cases 
has been published by Hall (17). 
Jeffreys (24) recommended for dosing pups, the use of ordinary syringe 
rubber tubing 5 inches long with an outside diameter of inch and a 
bore of inch, the tip to be rounded with sandpaper. This is fitted 
with a pliable plunger with a button in the end outside of the tube and 
with the other end blunt. The mouth of the fox is held open with a 
speculum, and the end of the tube is oiled and inserted into the upper 
end of the esophagus before the capsule is discharged. The drug is given 
in capsules of sizes No. o, 1, 2, and 3. 
Fitzgerald (6) has described and figured a balling gun and speculum 
suitable for the administration of capsules of carbon tetrachlorid to foxes, 
and has discussed the technic of this treatment. The balling gun 
has a rigid barrel, prolonged by a flexible tip, and is provided with a 
flexible plunger. 
The survival of 2 animals out of 3 after such a large dose as 18.6 cc. 
by drench is especially interesting in view of the report by Allen (r) on 
the effect of various anthelmintics on foxes. He found that chloroform 
was extremely toxic for foxes, killing 50 per cent of the animals treated, 
even though the dose used was too low to secure satisfactory anthelmintic 
action. He found that thymol in a dose which was 87.8 per cent effective 
against hookworms killed 18.7 per cent of the animals treated; when the 
dose was reduced to give an efficacy of 33 per cent, the fatalities totaled 
5.8 per cent of the animals treated. It would therefore appear that 
carbon tetrachlorid solves the question of safety in treating foxes for 
hookworms, for the therapeutic dose rate of 0.3 cc. per kilo for removing 
hookworms (the dose for dogs and the one which has been used on foxes 
with satisfactory results in a number of cases which have come to our 
attention) has a safety factor of 9 when compared with the dose rate of 
2.7 cc. per kilo which was survived by 2 out of 3 foxes to which it was 
administered in a drench. Allen (2) has since stated that he has used 
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