PLEURO-PNEUMONTA IN AUSTRALIA. 
365 
1st. Primary causes are those which first operate on the production 
of a new disorder. Of course, pleuro-pneumonia epizootica must have 
been at first produced, assuming' vvliat may be termed spontaneous pro¬ 
duction. 
Now, we know that there are some men standing' high in scientific 
circles, who argue that because it was first so introduced, it must of 
necessity be so produced again in every individual case; but there are 
too many dead facts against this theory. 
For my own part, I cannot entertain the notion, as everything seems 
dead against it. 
What may have been the primary cause or causes of pleuro-pneumonia 
epizootica, I do not know, but this I do know, that the exposing of 
healthy cattle to the virus from diseased animals, in such a way that it 
becomes absorbed, is now the primary cause of production. 
2ndly. Predisposing causes are those which arise out of a peculiar 
state of the constitution, made so by the inheritance of parental weak¬ 
ness, or from long-continued ill-treatment. 
The communication of parental points depends much on the tempera¬ 
ment of each parent. If the temperament be nearly balanced, the 
offspring will partake equally of each ; but if there be a preponderance 
on one side, the offspring will take most from the parent with the 
stronger temperament. 
Hence, should there be a chest weakness in anyone, that one will com¬ 
municate the weakness or tendency to disease if he or she possess the 
stronger temperament. 
Many of the foetus found in the wombs of diseased cattle had also 
the disease. 
3rdly. Exciting causes are such as exist in the speedy development 
of the disease, such as cold damp air, hot burning winds, filthy yards, 
or sheds, hard work, and hard unnatural treatment of any kind. In 
fact, the subjecting an animal to any new course of treatment, diverting 
or forcing it from its wonted habits, may act as strong exciting causes. 
The most common exciting causes in this country will be drafting, 
tailing, and driving the cattle long journeys. 
SYMPTOMS. 
The external symptoms common to this disease will not be easily 
detected among bush cattle, first, because their great constitutional 
strength (as compared with animals more under domestication) prevents 
the disease at first from making a decided stroke; and even though it 
does, the animal never suffers nor shows the same amount of pain. 
Their habits of life, too, are such that immediately on the approach 
of man a degree of alarm takes hold of them ; and then all symptoms 
are shrouded, unless of a most aggravated nature. 
Still a practised eve will soon see—if the coat stares and appears 
drier than usual—if the animal appear crouched up when standing, or 
cramped when walking or running; if he be in this state, the eye will 
appear swollen, and watery elfusion flowing from inner canthus ; nose 
dry, inferior opening wider than usual, and a thin, watery discharge 
running from it. The disease has just commenced in the lungs. 
After the malady has proceeded into the second stage, the discharge 
from nostril is white and thick, sticking in patches about it. 
In the third stage you have, in addition, a short grunt of a cough, 
and all the above-mentioned symptoms accelerated. 
