628 
REVIEW— ON THE EPIZOOTIC IN CATTLE. 
has, within our remembrance, proved in horses. This Mr. Dun 
ascribes to the “ essential” difference between the two diseases, or 
between pneumonia, pleurisy or bronchitis, and pleuro-pneumonia 
in cattle, which he states to reside in “ that typhoid or adynamic 
fever so pathognomonic of epizootic diseases.” Whether this can 
be said to be arising from a difference in the nature of the disease 
itself, or to be one springing out of the generic nature of the ani- 
mal, or out of the circumstances under which the animal is invaded 
by the disease, we have not time now to inquire. Let it suffice 
to remark, en passant , that, in the pulmonic form of influenza in 
horses, we all know that the tendency to debility and prostration 
is predominant, and that this sometimes leads on to low or ady- 
namic fever — in some cases, indeed, to something resembling or 
approaching to typhoid fever ; but, that such fever assumes the 
hopeless, malignant , “ asphyxiated ” form described by Mr. Dun, is 
not certainly among any of our ordinary observations. 
With these few remarks we find we must, and we do so reluct- 
antly, bring our review to a conclusion ; which we shall do witii 
giving at length Mr. Dun’s resume. 
“ The principal facts adduced in the foregoing pages may, by 
way of resume , be briefly brought under review as follows. When 
any disease assumes an epidemic or epizootic form, the number of 
cases of other diseases very much decreases. There seems to be 
something in the animal constitution which favours its development, 
and all other diseases converge as it were, for the time, into the 
one absorbing focus. 
“ Pleuro-pneumonia seems to result from a modification of the 
same causes as induce other epidemic or epizootic diseases. What- 
ever the other exciting causes may be, contagion is certainly the 
principal one. Of the many other alleged causes, none possess all 
the essential characteristics of an exciting cause; some are not 
uniformly present, and do not constantly precede the disease, while 
the operation of others is inadequate to produce the effects imputed 
to them ; and, therefore, although they may possess some of the 
properties which characterise exciting causes, they do not exhibit 
all the characteristics, and, consequently, are not entitled to be 
considered as the efficient exciting causes of any epidemic or epi- 
zootic disease. 
“ The remote or predisposing causes of pleuro-pneumonia are 
numerous, and include whatever reduces the vigour of the system, 
disturbs the operation of important functions, or infringes those 
