JOURNAL OF AGMUHTURAL RESEARCH 
Yol. XXIX Washington, D. C., October 1 , 1924 ' No. 7 
CRITICAL TESTS OF MISCELLANEOUS ANTHELMINTICS * 1 
By Maurice O. Hall, Zoologist, Zoological Division, .and Jacob E. Shillinger. 
Veterinary Inspector, Biochemic Division, Bureau of Animal Industry, United 
States Department of Agriculture 
INTRODUCTION 
By critical tests of anthelmintics is 
meant tests of these drugs by their 
administration in definite known doses 
to animals, with subsequent collection 
for a suitable length of time of all 
worms passed and the post-mortem 
examination of the animals with the 
collection of all worms then present. 
Identification of the worms collected 
ante-mortem and post-mortem, and 
addition of the numbers of those of the 
same kind, then give the total number 
of each kind present at the beginning of 
the experiment. The relation of the 
number of each kind passed to the total 
number present at the beginning of the 
experiment is ascertained in percentages 
and this percentage is arbitrarily taken 
as the percentage of efficacy of the 
anthelmintic. Such critical testing has 
been carried on for about 10 years in 
the Zoological Division of the Bureau 
of Animal Industry, and hundreds of 
such experiments show that when 
properly interpreted the figures thus 
obtained are a good index of the effi¬ 
cacy of an anthelmintic. Interpre¬ 
tation is necessary, since anthelmintic 
efficacy varies with several factors 
such as: 
The drug. —Its amount, composi¬ 
tion, age, solubility, concomitant effects 
(such as production of vomition, pur¬ 
gation, or constipation, etc.), mode of 
administration (such as in hard cap¬ 
sules, soft capsules, enteric-coated cap¬ 
sules, by stomach tube, by rectum, 
subcutaneously, intramuscularly, in¬ 
travenously, intratracheally, etc.). 
The operator. —His accuracy, tech¬ 
nic, familiarity with the animal's 
anatomy, skill in handling animals, 
etc. 
The experiment animal. —Its spe¬ 
cial physiology, physical condition, age, 
peculiar conditions or existing lesions or 
other pathological conditions, such as 
atonic and distended stomachs, the 
complicated stomach of ruminants, etc. 
Concomitant procedure in treat¬ 
ment.' —Fasting, diet, omission of purga¬ 
tives, use of different purgatives, etc. 
The worms. —Number, size, rela¬ 
tively inaccessible locations like the 
cecum, occurrence in cysts or nodules 
or in the mucosa or under mucus or 
hemorrhagic coverings, occurrence of 
larvae and of adults with protective 
cuticles, etc. 
Like many scientific investigations, 
these studies consist in correlating two 
or more variables; the number here is 
many more than two. Failures in 
anthelmintic medication may often be 
explained by careful consideration of 
these factors; and modifying those 
factors capable of modification may 
convert failure into success. 
TESTS OF A COMBINATION OF 
CARBON TETRACHLORIDE, CHE- 
NOPODIUM, AND ARE COLINE HY¬ 
DROBROMIDE FOR WORMS IN 
DOGS 
PROTOCOLS 
Dog No. 568; 7 kg.; 2.1 cc. of.mix¬ 
ture of 3 parts carbon tetrachloride 
and 1 part oil of* chenopodium by 
volume, with one-fourth grain of 
arecoline hydrobromide; animal died 
within 24 hours; post-mortem, ex¬ 
tensive cirrhosis of liver and presence 
of Dirofilaria immitis in the heart; no 
worms passed and none in digestive 
tract, hence no conclusions as to 
efficacy of the treatment. Dirofilaria 
1 Received for publication Apr. 19, 1924—issued January, 1925. 
Journal of Agricultural Research, Vol. XXIX, No. 7 
Washington, D. C. Oct. 1,1924 
Key No. A—84 
99184—25t-1 
(313) 
