May 17,1924 
Immunology of Bovine Infectious Abortion 
611 
RESISTANCE OF TREATED AND CONTROL ANIMALS 
During the first gestation period 10 of the 11 vaccinated animals produced 
living calves. One abortion occurred in this group, heifer No. 447, from the 
fetus of which Bacterium abortus was isolated. Another animal, cow No. 410, 
produced a living calf at the expiration of a 229-day gestation period. When 
she was slaughtered ten days later Bacterium abortus was isolated from her uterus. 
Failure was experienced in demonstrating the presence of Bacterium abortus in 
the placentas or uterine fluids of any of the other 9 animals of this group at time 
of parturition, although cultural efforts and guinea-pig inoculations were prac¬ 
ticed in all cases. 
In the bacterin-treated group 2 heifers, No. 423 and 401, produced living 
calves at the expiration of gestation periods of 282 and 273 days, respectively. 
Failure was experienced in isolating Bacterium abortus from the placentas or 
uterine fluids of these 2 animals at time of parturition. Bacterin-treated heifers 
404 and 464 expelled dead calves that were shown to harbor Bacterium abortus 
infection. 
Any comparison of the amount of exposure in these cases with that sustained 
by animals in infected herds under natural conditions is more or less conjectural, 
but that it was severe is evidenced by the fact that 7 of the 8 controls subse¬ 
quently aborted, and Bacterium abortus was isolated from the fetuses, placentas, 
or uterine fluids of all 8 subjects. 
Table I shows the dates of vaccination, the intervals between treatment and 
breeding dates, the time that elapsed between conception and exposure, the 
length of the gestation periods, and the final results obtained. 
Table I.— Immunization • results in animals subjected to artificial exposure to 
Bacterium abortus 
TREATED WITH ABORTION VACCINE 
Experimental 
animal 
Heifer 402. 
Heifer 409. 
Heifer 417. 
Heifer 418. 
Heifer 419. 
Heifer 427. 
Heifer 462. 
Heifer 447 
Cow 408.. 
Cow 410- 
Cow 416.. 
Exposure 
material 
(fetal- 
stomach 
Ges¬ 
con¬ 
Results of 
Date of 
Date of 
Date of 
tents) 
ta¬ 
tion 
Outcome of 
uterine ex¬ 
amination 
for Bad. 
treatment 
breeding 
exposure 
pregnancy 
| 
pe¬ 
Q 
1 
i 
riod 
abortus 
! § 
. 
! 
© 
a 
o 
IS 
; 
Cc. 
Days 
Mar. 2,1917 
Apr. 27,1917 
Nov. 2,1917 
42 
5 
276 
Living calf.. 
Negative, 
Aug. 29,1918 
Nov. 13,1918 
74 
50 
279 
.do. 
Do. 
Oct. 3,1919 
Mar. 18,1920 
May 10,1920 
110 
126 
20 
22 
} 280 
.do- 
Do. 
Mar. 2,1917 
Apr. 3,1917 
June 8,1917 
21 
50 
282 
.do. 
Do. 
Mar. 23,1917 
July 24,1918 
Aug. 20,1918 
70 
25 
280 
_do_ 
Do. 
Oct. 24,1919 
Mar. 18,1920 
May 10,1920 
110 
126 
20 
20 
} 284 
_do. 
Do. 
Feb. 1,1917 
May 25,1917 
Dec. 13,1917 
54 
30 
272 
.do. 
Do. 
July 12,1918 
Aug. 20,1918 
70 
30 
267 
.do_ 
Do. 
Oct. 24,1919 
Mar. 18,1920 
110 
20 
} 279 
.do_ 
Do. 
May 10,1920 
126 
22 
Mar. 2,1917 
July 25,1918 
Aug. 20,1918 
70 
25 
284 
.do. 
Do. 
Mar. 23,1917 
Oct. 8,1919 
Mar. 18,1920 
110 
20 
} 277 
_do. 
Do. 
May 10,1920 
126 
22 
Mar. 30,1918 
Dec. 30,1918 
Feb. 24,1919 
80 
60 
} 281 
.do. 
Do. 
Mar. 19,1919 
88 
25 
Apr. 21,1920 
M.y 10,1920 
126 
22 
j 281 
.do_ 
Do. 
Mar. ^,1917 
Apr. 6,1917 
July 17,1918 
June 8,1917 
21 
50 
282 
.do. 
Do. 
Aug. 20,1918 
70 
25 
278 
.do_ 
Do. 
Oct. 3,1919 
Mar. 18,1920 
110 
20 
} 282 
_do_ 
Do. 
May 10,1920 
126 
22 
Jan. 10,1919 
Mar. 12,1919 
May 24,1919 
92 
50 
285 
.do_ 
Do. 
Apr. 26,1920 
May 10,1920 
126 
22 
284 
_do_ 
Do. 
Mar. 30,1918 
July 1,1918 
Nov. 13,1918 
74 
30 
259 
Abortion_ 
Positive. 
Feb. 24,1919 
Apr. 12,1919 
May 24,1919 
92 
50 
283 
Living calf.. 
Negative. 
Mar. 2,1920 
Apr. 22,1920 
May 10,1920 
126 
22 
229 
Weak calf... 
Positive. 
Mar. 2,1920 
May 5,1920 
May 10,1920 
126 
22 
290 
Living calf.. 
Negative. 
