As very little is, at present, known of the nature of this disease, we
give the reader the views of Mr. Dun, who received the gold medal
offered by the Agricultural Society for the best essay on this subject.
"The causes of the disease, both immediate and remote, are subjects full
of interest and importance; and a knowledge of them not only aids in the
prevention of disease, but also leads the practitioner to form a more
correct prognosis, and to pursue the most approved course of treatment.
It is, however, unfortunate that the causes of pleuro-pneumonia have not
as yet been satisfactorily explained. No department of the history of
the disease is less understood, or more involved in doubt and
obscurity. But in this respect pleuro-pneumonia is not peculiar: it is
but one of an extensive class which embraces most epidemic and epizooetic
diseases. And if the causes which produce influenza, fevers, and
cholera, were clearly explained, those which produce pleuro-pneumonia
would, in all probability, be easy of solution.
"Viewing the wide-spread and similar effects of pleuro-pneumonia, we may
surmise that they are referable to some common cause. And although much
difference of opinion exists upon this subject, it cannot be denied that
_contagion_ is a most active cause in the diffusion of the disease.
Indeed, a due consideration of the history and spread of
pleuro-pneumonia over all parts of the land will be sufficient to show
that, in certain stages of the disease, it possesses the power of
infecting animals apparently in a sound and healthy condition, and
otherwise unexposed to the action of any exciting cause. The peculiarity
of the progress of this disease, from the time that it first appeared in
England, is of itself no small evidence of its contagious nature. Its
slow and gradual progress is eminently characteristic of diffusion by
contagion; and not only were the earlier cases which occurred in this
island distinctly proved to have arisen from contact with the Irish
droves, but also subsequent cases, even up to the present day, show
numerous examples in which contagion is clearly and unequivocally
traceable.... Although pleuro-pneumonia is not produced by the action of
anyone of these circumstances alone, [referring to noxious effluvia,
&c.,] yet many of them must be considered as predisposing to the
disease; and although not its immediate exciting causes, yet, by
depressing the physical powers, they render the system more liable to
disease, and less able to withstand its assaults. Deficient ventilation,
filth, insufficient and bad food, may indeed predispose to the disease,
concentrate the animal effluvia, and become the _matrix_ and _nidus_ of
the organic poison; but still, not one, alone, of these circumstances,
or even all of them combined, can produce the disease in question. There
must be the subtle poison to call them into operation, the specific
influence to generate the disease."
"On the other hand, it appears probable that the exciting cause, whether
it be contagion, or whatever else, cannot, of itself, generate the
disease; but that certain conditions or predisposing causes are
necessary to its existence, and without which its specific effects
cannot be produced. But although these _remote_ or _predisposing_ causes
are very numerous, they are often difficult of detection; nay, it is
sometimes impossible to tell to what the disease is referable, or upon
what weak point the exciting cause has fixed itself. A source of
perplexity results from the fact.... The predisposing causes of the
disease admit of many divisions and subdivisions; they may, however, be
considered under two general heads--_hereditary_ and _acquired_.
"With reference to the former, we know that good points and properties
of an animal are transmitted from one generation to another; so also are
faults, and the tendencies to particular diseases. As in the same
families there is a similarity of external form, so is there also an
internal likeness, which accounts for the common nature of their
constitution, modified, however, by difference of age, sex, &c.
"Among the acquired predisposing causes of pleuro-pneumonia may be
enumerated general debility, local weakness, resulting from previous
disease, irritants and stimulants, exposure to cold, damp or sudden
changes of temperature, the want of cleanliness, the breathing of an
atmosphere vitiated by the decomposition of animal or vegetable matters,
or laden with any other impurity. In short, under this head may be
included every thing which tends to lower the health and vigor of the
system, and consequently to increase the susceptibility to disease.
"The primary symptoms of pleuro-pneumonia are generally obscure, and too
often excite but little attention or anxiety. As the disease steals on,
the animal becomes dull and dejected, and, if in the field, separates
itself from its fellows. It becomes uneasy, ceases to ruminate, and the
respirations are a little hurried. If it be a milk-cow, the lacteal
secretion is diminished, and the udder is hot and tender. The eyes are
dull, the head is lowered, nose protruded, and the nostrils expanded.
The urine generally becomes scanty and high-colored. It is seldom
thought that much is the matter with the animal until it ceases to eat;
but this criterion does not hold good in most cases of the disease, for
the animal at the outset still takes its food, and continues to do so
until the blood becomes impoverished and poisoned; it is then that the
system becomes deranged, the digestive process impaired, and fever
established. The skin adheres to the ribs, and there is tenderness along
the spine. Manipulation of the trachea, and percussion applied to the
sides, causes the animal to evince pain. Although the beast may have
been ill only three days, the number of pulsations are generally about
seventy per minute; but they are sometimes eighty, and even more. In the
first stage, the artery under the jaw feels full and large; but as the
disease runs on, the pulse rapidly becomes smaller, quicker, and more
oppressed. The breathing is labored, and goes on accelerating as the
local inflammation increases. The fore extremities are planted wide
apart, with the elbows turned out in order to arch the ribs, and form
fixed points for the action of those muscles which the animal brings
into operation to assist the respiratory process. In pleuro-pneumonia,
the hot stage of fever is never of long duration, [_simply because there
is not enough vitality in the system to keep up a continued fever_.] The
state of collapse quickly ensues, when the surface heat again decreases,
and the pulse becomes small and less distinct. We have now that low
typhoid fever so much to be dreaded, and which characterizes the disease
in common with epizooetics.
"... The horse laboring under pleuro-pneumonia, or, indeed, any
pulmonary disease, will not lie down; but, in the same circumstances,
cattle do so as readily as in health. They do not, however, lie upon
their side, but couch upon the sternum, which is broad and flat, and
covered by a quantity of fibro-cellular substance, which serves as a
cushion; while the articulation between the lower extremities of the
ribs admits of lateral expansion of the chest. In this position cattle
generally lie towards the side principally affected, thus relieving the
sounder side, and enabling it to act more freely. There is sometimes a
shivering and general tremor, which may exist throughout the whole
course of the disease. (This is owing to a loss of equilibrium between
the nerves of nutrition and the circulation.) ... As the case advances
in severity, and runs on to an unfavorable termination, the pulse loses
its strength and becomes quicker. Respiration is in most cases attended
by a grunt at the commencement of expiration--a symptom, however, not
observable in the horse. The expired air is cold, and of a _noisome_
odor. The animal crouches. There is sometimes an apparent knuckling over
at the fetlocks, caused by pain in the joints. This symptom is mostly
observable in cases when the pleura and pericardium are affected. The
animal grinds its teeth. The appetite has now entirely failed, and the
emaciation becomes extreme. The muscles, especially those employed in
respiration, become wasted; the belly is tucked, and the flanks heave;
the oppressive uneasiness is excessive; the strength fails, under the
convulsive efforts attendant upon respiration, and the poor animal dies.
"In using means to prevent the occurrence of the disease, we should
endeavor to maintain in a sound and healthy tone the physical powers of
the stock, and to avoid whatever tends to depress the vital force.
Exposure to the influence of contagion [and infection] must be guarded
against, and, on the appearance of the disease, every precaution must be
used to prevent the healthy having communication with the sick. By a
steady pursuance, on the part of the stock proprietor, of these
precautionary measures, and by the exercise of care, prudence, and
attention, the virulence of the disease will, we are sure, be much
abated, and its progress checked."
As the reader could not be benefited by our detailing the system of
medication pursued in England,--at least we should judge not, when we
take into consideration the great loss that attends their _best
efforts_,--we shall therefore proceed to inform the reader what the
treatment ought to be in the different stages of the disease.
_General Indication of Cure in Pleuro-Pneumonia._--Restore the
suppressed evacuations, or the secretions and excretions, if they are
obstructed.
If bronchial irritation or a cough be present, shield and defend the
mucous surfaces from irritation. Relieve congestions by equalizing the
circulation. Support the powers of the system. Relieve all urgent
symptoms.
* * * * *
_Special Practice._--Suppose a cow to be attacked with a slight cough.
She appears dull, and is off her feed; pulse full, and bowels
constipated; and she is evidently out of condition.
Then the medicines should be anti-spasmodic and relaxant, tonic,
diaphoretic, and lubricating.