INFECTIOUS ABORTION IN CATTLE 203 
In the few recorded cases where cows with retained afterbirth have 
been promptly slaughtered, there has been found in the uterus, 
between it and the afterbirth, the “exudate of contagious abortion’”’ 
containing the Bang organism. It has not been shown that any other 
organism may exist in the pregnant uterus for an extended period of 
time: No other cause for retained afterbirth has been demonstrated. 
Diagnosis. With infectious abortion, as with tuberculosis, the 
animals may be infected and yet give no physical evidence of that fact. 
The premonitory symptoms are usually brief in duration and there 
are no lesions in evidence until the abortion occurs. It is impossible, 
therefore, to pick out. by means of physical examination cows that are 
infected. The specific organism cannot be detected in the uterine 
discharge until just before and following the expulsion of the fetus. 
The diagnosis, therefore, must be made from some specific reaction or 
test of which four have been described, namely: abortin, precipita- 
tion, complement fixation and agglutination. 
Abortin is analogous to tuberculin, made from bouillon cultures of 
the abortion organism. It resembles tuberculin in the method of its 
preparation and use. It has not been satisfactory. The precipita- 
tion test is likewise unsatisfactory. The complement fixation was 
applied first by M’Fadyean who was enthusiastic in its favor. The 
time required to make the test and the dangers of error, especially 
where one is not making it constantly, are so great that it is not 
entirely satisfactory as a practical diagnostic method. The aggluti- 
nation test is very satisfactory. A positive reaction to complement- 
fixation or agglutination test does not determine whether the animal 
has aborted or is going to abort, but it does indicate that the animal 
is at present or has been infected with Bactertum abortionis. 
Prevention. Dairyman have come to believe that if they keep 
animals that abort away from their sound cattle the trouble does not 
appear among them. As it affects young cows, it is the practice in 
some places to keep the young animals separated from the others 
until they have become free from the infection or at least until they 
have passed the period when it is apt to occur after which they are 
admitted to the herd of older cows with impunity. 
Williams has madc the following statement concerning the control 
of abortion: 
“We are in great need of a logical and comprehensive plan for com- 
bating abortion. Up to the present time, little definite progress has 
