162 
APTHA, OR THRUSH IN THE HORSE. 
the odour emitted in thrush is very different, and much less 
offensi ve. 
From the foregoing extracts it will be perceived, that it has 
been considered by some as a disease, sui generis, and by others 
as owing to heat in the brain and stomach ; while others con¬ 
sider it as commencing in the mouth, and extending down to the 
stomach. The reverse of this is, in my opinion, the case ; it ex¬ 
tends from the stomach upwards. 
You will, I am persuaded, concur with me in thinking that 
some definite term should be given to this affection of the mouth. 
I am unwilling unnecessarily to add to our increasing nomen¬ 
clature of disease, but if such an affection has existence (and on 
that point there can be no doubt), it surely is worthy of some 
distinguishing appellation; and, for aught I know, ‘^Thrush” is 
unobjectionable: but let us not confound with it a multitude of 
other maladies to which it bears not the slightest resemblance. 
I will not trespass longer on your time, but proceed to state 
what I consider constitutes the malady, I am fully persuaded 
that, except the partial soreness of the gums during dentition, or 
in consequence of injuries of different kinds, the mouth is never 
primarily affected, but that it is secondarily or sympathetically 
so; and that these effects are produced solely by a derangement 
of that important viscus the stomach, or, to a greater or less 
extent, the whole alimentary canal; but this will fall under the 
head of 
Causes. —There are many with which I am totally unacquaint¬ 
ed ; but, allowing the stomach to be an organ of such peculiar and 
vital importance in the animal economy—that it requires to be 
attended to more than any other—and that when injured, every 
part of the system seems to participate in the injury—I come to the 
conclusion that whatever may produce derangement or disease 
of this all-important viscus, may produce aptha, although I by 
no means wish you to infer from this, that I consider it must 
necessarily do so. Many facts come daily before our eyes, in 
which diseases of other, and very different systems, are connected 
with or caused by a morbid state of the stomach; I need only 
mention staggers, amaurosis, surfeit, and chronic cough. 
I will, however, speak of that alone which has come under my 
own immediate knowledge; and from that I am compelled to 
infer, that among the more immediate causes of thrush, sudden 
changes of food, and particularly from grass to hard meat (hay 
and oats), and whether of a good or a bad quality, but given 
in undue quantity, and the stomach being unprepared for the 
change, is one of the most frequent causes of thrush. 1 have 
seen it occur while the animal was at grass; but in these cases I 
