689 
ON ABOliriON IN CATTLE. 
bull. About a fortnight afterwards, another cow cast her calf, 
though she had been removed to a distance of two miles. The 
next six cases, which happened during the months of April, May, 
June, July, and October, require no particular remarks, as the 
mothers all perfectly recovered, though their offspring never ex¬ 
hibited any signs of life. After these, another heifer, that had been 
removed to a considerable distance immediately after taking the 
bull, in order to be clear of all communication with the rest, aborted 
in the month of August, at the end of the seventh month of gestation. 
It may be well to remark, that thirteen half-bred Irish cattle, bought 
at York, and introduced amongst the rest of the stock, and at all 
periods of their gestation, calved well, without exhibiting the least 
symptom of disease. 
From the foregoing account it will be impossible to explain the 
cause of this remarkable occurrence by considering abortion to be 
a disease of a contagious nature, and that - it may be transmitted 
from one to another bv communication or contact, as in this instance 
every precaution was taken to prevent it from spreading, by sepa¬ 
rating those in which the complaint had first exhibited itself from 
the other cattle, and removing them away to some distant situation. 
I think that the cause may, with greater probability, be referred 
to a certain condition of the atmosphere which seems to favour the 
occurrence of abortion. To this only can be attributed those fre¬ 
quent abortions sometimes observed, which have even assumed an 
epidemic form. Many predisposing causes may, however, exist on 
the part of the mother; for example, irritability or too great rigidity 
of the uterine fibres and bloodvessels, which, by preventing the 
regular enlargement of the gravid uterus, gives rise to premature 
expulsion of its conterits. 
A very frequent cause of abortion is a diseased condition of the 
foetus itself, or its membranes, by which it is deprived of life, and 
afterwards expelled from the uterus like a foreign body. All cases 
of abortion cannot, however, be referred to a diseased state of the 
uterus or its contents, since it cannot be doubted that this process 
may be brought on by accidental separation of the placenta, in con¬ 
sequence of an unusual intlux of blood to the vessels of the uterus, 
or contraction of the uterus itself. If this takes place to a consider¬ 
able extent, the progress of gestation will be arrested, and, in a 
longer or shorter period, the ovum will be expelled. 
In plethoric cases, very slight causes may give rise to extravasa¬ 
tion of blood between the uterus and placenta, with the other con- 
sc(|uences now described. I may here remark, that the cattle were 
all in good condition, and well fed; from which circumstance I was 
leil to suppose that a plethoric state of the general circulation would 
favour a determination of blood to the uterine organs, or assist the 
