ANTHELMINTIC EFFICIENCY OF CARBON TETRA- 
CHLORID IN THE TREATMENT OF FOXES 1 
By Karl B. Hanson and H. L. Van Volkenberg , 2 Assistant Biologists, Division 
of Economic Investigations, Bureau of Biological Survey, United States Depart¬ 
ment of Agriculture 
Investigations conducted by the Bureau of Biological Survey of the United 
States Department of Agriculture tend to indicate that many foxes, both in 
the wild and on ranches, are infested with hookworms, principally Uncinaria 
stenocephala and occasionally Ancylostoma caninum. Although many foxes 
harboring hookworms manifest no apparent symptoms of infestation, observa¬ 
tions made indicate that heavy infestations may be attended with impaired 
health and may even result in death. 
In view of the fact that Hall (#) 3 found chemically pure carbon tetrachlorid 
in sufficient doses to be relatively effective and safe in the treatment of dogs for 
the removal of hookworms, it was considered advisable to test this drug as an 
anthelmintic for foxes. The results of the experiments conducted are reported 
in this paper. 
ANTHELMINTIC EXPERIMENTS 
In the experiments on foxes, the technic was similar to that used by Hall 
alone or in collaboration with other investigators (2, 3 ). Chemically pure carbon 
tetrachlorid was given in hard gelatine capsules or in soft elastic globules to 
foxes that had been fasted from 16 to 20 hours. The only animals which were 
not fasted the usual period were foxes No. 792 and 793, two 1-month-old 
nursing pups. No purgative was given before or after the administration of 
the dose, except to fox No. 88. 
After treatment each animal was confined in a small cage which was provided 
with a heavy gauge 1-inch woven-wire bottom and set on supports, with a large 
.galvanized iron collecting pan underneath to catch all feces and worms passed. 
In the use of cages of this type it was found that the number of worms eaten or 
adhering to the feet or fur of the foxes was reduced to a minimum. The feces 
and worms passed were collected daily, screened, and all worms passed were 
identified and counted. 
From three to five days after treatment the animals were killed with either a 
subcutaneous or an intrathoracic injection of strychnin sulphate solution. A 
post-mortem examination was made of each animal to determine the kind and 
number of worms remaining in the alimentary tract; also to make note of the 
gross pathological changes, especially those apparently due to the drug. The 
percentage efficacy of the treatment in all cases was the figure obtained by 
ascertaining the relation of the number of worms passed to the combined total 
of the number passed after treatment and the number found on post-mortem. 
1 Received for publication February 25, 1924 
* Dr. H. L. Van Volkenberg resigned March 31, 1923, to work under the Bureau of Fisheries on the 
diseases and parasites of blue foxes on the Pribilof Islands, Alaska. 
8 Reference is made by number (italic) to “Literature cited,” . 337. 
Journal of Agricultural Research, 
Washington, D. C. 
( 331 ) 
Vol. XXVIII, No. 4 
April 26, 1924 
Key No. Q-2 
