68 
EPIZOOTIC PLEUROPNEUMONIA. 
the “ asthenic” form. This is often overlooked or insufficiently 
estimated, where, owing to weak vital energy, the inflammatory 
irritation assumes a low grade and the disease slowly extends, 
obliterating the small bronchi, destroying their functions, and pre- 
venting those changes from taking place in the blood which are 
requisite for the support of the nervous and vital manifestations. 
In other words, this state of the lungs depends upon a weakened 
and otherwise morbid state of the system, generally occasioning 
specific changes in their organic sensibility, and depending ori- 
ginally upon a depraved state of the vital powers in connexion 
with alterations of the circulating fluids, the albuminous parts of 
which are deposited in large quantities, and subsequently undergo 
a low and morbid state of organization. 
The dropsical condition of the lungs arises principally from an 
enormous effusion of lymph and serum into the interlobular struc- 
ture, which is often increased in thickness nearly half an inch, form- 
ing pale yellow lines. These are particularly marked under the 
pleura. The darker parts consist of interstitial cellular tissue injected 
with red particles of blood, giving to the affected parts the appear- 
ance of beautiful striated and variegated marble. 
The density of the lungs being thus produced — the air-cells being 
obliterated — is so great in the affected parts, that they sink in water, 
and, in many cases, the lung on one side will weigh as much as 
sixty pounds, being five times its natural weight. 
In most cases the pleura covering the diseased lung, and also 
that lining the chest, become involved, and effusion into the 
thorax or extensive adhesions are found to exist between the lungs, 
ribs, diaphragm, and even to the pericardium. 
Symptoms . — The precursory symptoms are very obscure ; but 
there will generally be observed a dry, short cough — quick, short 
breathing, especially on motion — the pulse, when the animal is at 
rest, but little affected, yet much accelerated by the slightest 
exertion : these circumstances often continue for a week or even 
longer, yet frequently unobserved, or, if seen, little or no notice 
being taken of it. 
As the disease advances, these circumstances become more 
urgent. The pulse may be much accelerated, but is usually com- 
pressible or soft, or even small — an occasional short cough or 
rather grunt is heard — respiration is short and frequent — the pupil 
of the eye is dilated — the coat stares — the skin and muzzle are dry 
— the appetite and rumination suspended — the bowels torpid. 
Symptoms of pleuritic irritation next make their appearance, 
proceeding either from the unusual degree of tension experienced 
by the pleura, owing to the turgid or expanded state of the lung 
enveloped by it, or from consecutive inflammation. The animal is 
