116 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
been reported, there is no doubt that the milk is injurious 
to health because numerous cases of meat poisoning are 
on record from the use of meat from cows slaughtered 
while suffering from this condition. Cows affected with 
septic metritis should therefore be removed from the milk 
stable and the milk should not be used for food. 
RETAINED PLACENTA 
Following retention of the placenta, there is a dis- 
charge from the uterus which frequently contains par- 
ticles of the fetal membranes and cotyledons which are 
undergoing putrefaction, also pus, pyogenic organisms, 
and putrefactive bacteria. The tail, thighs, and udder 
become soiled with the discharges and the milk may be 
contaminated during milking. In cases where the milk 
has been centrifugalized and the sediment examined micro- 
scopically, large numbers of staphylococci and diplococci 
have been found. The milk will also give a positive re- 
action to the alcohol test, indicating that the secretion is 
not normal. Milk from cows with a purulent or putrid 
vaginal discharge should not be used for food purposes. 
Such cows should not be placed in the milk stable 
until the condition disappears, as there is a possibility of 
the discharge contaminating the milk of the other cows. 
INFECTIOUS ABORTION 
The milk of cows which have aborted contains the 
Bacillus abortus Bang very frequently, in some cases for 
months after the abortion. Immediately before and 
for several weeks after abortion, the bacillus is also elimi- 
nated through the vagina and may infect the milk second- 
arily. When the placenta is retained, the vaginal dis- 
charge also contains pyogenic and putrefactive organ- 
