434 
Journal of Agricultural Research 
Vol. XXX, No. 5 
Table I may be summarized as fol¬ 
lows: Eighteen dogs received one injec¬ 
tion of vaccine, 7 on May 25 and 11 on 
July 18. On September 12 the 18 
vaccinated dogs together with 8 control 
dogs received an intraocular injection 
of street virus. Of the 18 vaccinated 
dogs, 15 died of rabies. Of the 8 con¬ 
trol dogs 1 died of rabies and 1 of en¬ 
teritis. 
In this and the following experiments 
the diagnosis of rabies in vaccinated 
animals was always confirmed by micro¬ 
scopic examination and rabbit inocula¬ 
tions. 
The irregular outcome of this ex¬ 
periment is rather difficult of interpre¬ 
tation. The first thought that came 
to mind was the possibility of the 
vaccine sensitizing the animals, so that 
they succumbed to infection more 
quickly than nonvaccinated dogs. Sub¬ 
sequent experiments have not proved 
this to be the case, however, and the 
following is probably the cause of the 
irregularity of the result: The 18 vacci¬ 
nated dogs were housed in one barn, 
and these were the first to be exposed 
to the street virus. The 8 control 
dogs were housed in a second barn 
about one-fourth of a mile from the 
first. After the dogs in the first barn 
had been exposed the virus was carried 
in a small beaker to the second barn, 
where the control dogs were then in¬ 
jected. Exposure to sunlight or to 
some unknown factor probably caused 
an alteration of the virus between the 
first and second barns. The injections 
in both groups of animals were made 
by the writer, and the material was 
stirred well before each injection. 
Although the result of experiment 
No. 1 was irregular, it showed con¬ 
clusively that the single injection of a 
vaccine did not produce sufficient 
immunity to protect dogs against an 
intraocular injection of the street virus 
used. 
EXPERIMENT NO. 2 
It was decided to repeat the previous 
experiment. Three dogs were vacci¬ 
nated on July 18 and three on October 
11, 1922. On October 26 these six 
dogs, together with three control dogs, 
received an intraocular injection of 
rabies street virus, 0.1 c. c. of a 1:10 
dilution r>f the hippocampus and me¬ 
dulla of dog 26, dead of rabies (B. A. I. 
virus 474). The results are given in 
Table II. 
Summarizing Table II it appears 
that five of the six vaccinated dogs 
died of rabies. The death of the 
sixth could not be attributed to 
rabies. All three controls died of 
rabies. 
The diagnosis of rabies in the 
vaccinated animals was confirmed 
by microscopic examination and 
rabbit inoculations. In the control 
dogs the diagnosis was made clinically 
and by the demonstration of Negri 
bodies microscopically. 
The incubation period of the disease 
was about the same in the vaccinated 
dogs as in the controls, showing that 
Table II .—Data of experiment No. 2 
Dog 
No. 
Vaccine® 
Amount 
injected 
Date vaccine 
was injected 
Date exposed 
to virus * 
Result c 
Date of rabbit 
inoculation 
Result 
C.c. 
27 
B. 
5 
July 18,1922 
Oct. 26,1922 
Dead, Dec. 23, 
Dec. 27,1922 
Dead, Jan. 25, 
1922; rabies. 
1923; rabies. 
28 
C. 
3 
_do_ 
.do. 
Dead, Nov. 21, 
Nov. 23,1922 
Dead, Dec. 7, 
1922; rabies. 
1923; rabies. 
29 
A. 
5 
.do. 
.do. 
Dead, Nov. 15, 
Nov. 16,1922 
Dead, Dec. 26, 
1922; rabies. 
1923; rabies. 
30 
B. A. I. 
5 
Oct. 11,1922 
_do. 
Dead, Nov. 24, 
Nov. 25,1922 
Dead, Dec. 12, 
1922; rabies. 
1923; rabies. 
31 
_do_ 
3 
.do. 
.do. 
Dead, Dec. 8, 
Dec. 12,1922 
Dead, Dec. 26, 
1922; rabies. 
1923; rabies. 
32 
—do_ 
5 
.do. 
.do. 
Died suddenly, 
Dec. 15,1922 
Alive, Feb. 15, 
Dec. 14, 1922; 
1923. 
not rabies. 
33 
Control 
_do_ 
Dead, Nov. 24, 
dog. 
1922; rabies. 
34 
_do_ 
.do. 
Dead, Nov. 10, 
1922; rabies. 
35 
—do— 
.do. 
Dead, Dec. 14, 
1922; rabies. 
•Vaccines A, B, and C were from three different commercial houses manufacturing this product. 
Vaccine B. A. I. was prepared in the laboratory of the Bureau of Animal Industry. 
* The virus consisted of a 1:10 dilution in salt solution of the medulla and hippocampus of dog 26 
(B. A. I 474); 0.1 c. c. of this material was injected into the anterior chamber of the left eye. 
* Diagnosis of rabies was made by microscopic examination and, in the case of vaccinated dogs, by 
rabbit inoculations. 
