Contagious or Epizootic Abortion in Cows. 103 
It is not so easy to advise an owner when the agglutination 
test proves that a large proportion of the cows are already 
infected. If isolation of the diseased animals is possible it 
ought to be tried, but in the contrary case at the present time 
the only possible alternative to allowing the disease to run its 
course is to vaccinate one month after calving each cow in the 
herd. Such vaccinated cows should not be put to the bull 
within less than thiee months. Heifers that are to be brought 
into the herd should also be vaccinated three months before 
service. 
What is here referred to as vaccination is carried out by 
injecting living or dead artificial cultures of abortion bacilli 
under the skin. The use of dead bacilli in this way is devoid 
of danger but it is probable that it is of little value for confer- 
ring immunity. The injection of large doses of living bacilli 
does undoubtedly confer a considerable degree of immunity, 
but it must be remembered that it is a dangerous proceeding 
in the case of pregnant cows, and that even when the animal is 
non-pregnant at the time of vaccination it may cause abortion 
during the ensuing pregnancy if too short a period is allowed 
between vaccination and service. 
It is to be hoped that the trials of this method of dealing 
with outbreaks which have recently been made under the 
supervision of the Board of Agriculture and Fisheries will 
provide information to show whether it can be recommended 
as both safe and efficacious. 
Lastly, it may be pointed out that when it appears to be 
impossible to arrest an outbreak, owing to the lack of facilities 
for isolating the animals found to be already infected, the best 
plan is to endeavour to run the herd for the next year or two 
with as few changes as possible. To dispose of the cows that 
have aborted and replace them by fresh animals is objection- 
able, because the majority of animals make a complete recovery 
after abortion and in consequence of immunity are likely to 
carry their next calves to full term, whereas any healthy cows 
brought into an infected stock serve as fresh fuel to the fire. 1 
J. McFadyean. 
Royal Veterinary College, 
London, NAV. 
1 The author is indebted to Mr. A. L. Sheather, B.Sc., for the photographs 
from which the illustrations in the article have been prepared. 
