INFECTIOUS ABORTION. 
573 
even when the foetus and membranes have not been removed 
for some time, I have never known where such an abortion 
has been followed by a general abortion of the mares that 
were in connection with the one affected. 
In many instances when the first mare aborts, you will be 
informed by the owner or attendant that he believes she has 
received some injury, but such information is founded on 
about as much knowledge as that which the average man 
possesses who asserts that the animal affected with periodic 
ophthalmia has been struck by an attendant in the eye. 
The weather, wet or dry, warm or cold, appears to make 
no difference in this country, as the disease becomes epizo¬ 
otic during seasons of different temperature, appearing in 
some localities during a very cold, dry winter and in others 
just the opposite. 
. For a great many years the best authorities have believed 
that infection has played the sole part, and I do not think 
there will be much question here as to that, but from what 
does the infection spring? Is it necessary that an accidental 
abortion take place, and from the decomposition accompany¬ 
ing it the infectious germ is developed which is conveyed to 
others with such disastrous results? or is the germ developed 
independently and under certain favorable conditions attack¬ 
ing the foetal membranes, causing decomposition and subse¬ 
quent abortion ? I do not believe that the first proposition is 
correct, but 1 am inclined from my own observations to be¬ 
lieve that the latter is. Probably it is true that the infection 
becomes greater after redevelopment in the foetal mem¬ 
branes. Fleming states that mares that have carried their 
foetus nearly through the normal period of gestation, resist 
the infection and foal all right at the natural time. My ex¬ 
perience has been that the period of gestation makes no dif¬ 
ference, as mares lose their colts after having gone ten 
months and even longer. In such cases it is not uncommon 
to have a malpresentation with difficult parturition. The 
period of incubation is doubtful, and it can only be deter¬ 
mined by careful experiments. I have seen mares that had 
been removed from a place where several abortions had oc- 
