SPECIAL REPORT ON DISEASES OF CATTLE
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ny ways. The channel and method of administration depend on whether a general or local effect is desired, the condition of the animal, and the nature of the medicine that is to be given.
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gestion and cause local injury to the digestive organs, but may cause general poisoning of a severe and fatal type. The following molds have been shown (Dammann) to be dangerous in respe
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robang to push down any soft material, such as oats or chaff, as this generally condenses and renders firmer the obstructing substance by pressing its particles or elements together, so t
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e._--From the fact that this disease is largely one of regions, it is generally believed that some condition of the soil and water and of the local vegetation is responsible for it. It is
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aults in feeding than as a disease in itself. It occurs in almost all general fevers unless the bowels are involved in local disease, in obstructions of all kinds, from feeding on dry, bu
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he contents of the sac can not be returned into the abdomen, and this generally arises from the fact that some part of the contents of the sac has grown to or become adherent to the edges
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ote action may be exerted by the same drug. Poisons which act locally generally either destroy by corrosion the tissues with which they come in contact or by inhalation set up acute infla
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of chronic gastrointestinal catarrh, with indigestion, diarrhea, and general weakness and loss of condition. _Treatment._--The antidote for arsenic is a solution of hydrated oxid of iro
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onite is given whether indicated or not. Fortunately the dose used is generally small, and for this reason the damage done is much less than it would otherwise be. Aconite is one of the m
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the growth of bacteria, and bacteria may produce poisons in feeds. In general it may be said that any feed that is moldy, musty, or putrid is possibly dangerous. Silage, properly cured, d
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d often irregular. Respiration is difficult and rapid. There is great general weakness and depression. Death comes suddenly. _Treatment._--Treatment consists in supporting the animal by
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t of the diseases under consideration in this chapter. _Attitude and general condition._--The feeling of pain in animals suffering from serious affections of the organs of respiration is
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mucous membrane of the bronchial tubes. When a primary disease, it is generally the result of what is commonly known as "catching cold." It may be secondary to or complicated with many of
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without much uncertainty. The first signs may be those of frenzy, but generally at the start the animal is dull and sleepy, with little or no inclination to move about; the head may be pr
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and up on account of the paralysis of the hind quarters. This form is generally attributed to feeding on feeds containing insufficient protein and ash. It is most likely to occur in cows
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passing of a catheter is an operation which demands special skill. _General symptoms of urinary disorders._--These are not so prominent in cattle as in horses, yet they are of a similar
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his advanced stage to relieve dropsy and give tone to the kidneys and general system (oil of turpentine, 2 teaspoonfuls; bicarbonate of soda, 1 teaspoonful, repeated twice a day). Pure wa
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ere are exceptions, they are so rare that they do not invalidate this general rule. It is true that stone in the kidney or bladder is often found in the summer or in animals feeding at th
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sting the special cause of each as found in the feed, water, soil, or general conditions of health. This classification affords no guide to their location or symptoms, as calculi of the s
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c., in Cornell University._ [Revised by Adolph Eichhorn, D. V. S.] GENERAL DISCUSSION. Diseases of the generative organs are practically confined to animals which are kept for reprodu
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and general obstacles to conception should be carefully investigated and removed. The vigorous health which comes from a
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will refuse the male persistently, but these in no way invalidate the general rule. The bull, no matter how vigorous or how ardent his sexual instinct, can not be made to pay any attenti
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med these findings. _Cause._--The _Bacterium abortus_ of Bang is now generally recognized as the causative agent of the disease of cattle. Formerly it was thought that abortion was due t
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w, however, is not substantiated by other investigators, it being now generally accepted that the disease is only rarely responsible for abortion, and further, that it exerts no apparent
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either in the flank or with a trocar and cannula through the anus. GENERAL DROPSY OF THE CALF. This occurs from watery blood or disease of some internal organ, like the liver or kidne
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re beset with similar drawbacks, and are to be dealt with on the same general principles. (Pl. XVII, fig. 4.) With the back turned to one side the body should be rotated until the back tu
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se. No part is wedged into the pelvic passages as a complication. The general principles are the same as in faulty presentation fore and hind, and no time should be lost in making the man
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eet engaged in pelvis. A very serious malpresentation, in which it is generally impossible to save the fetus if delivery is far advanced. The indications are to force back the hind feet.
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even gangrene are shown in the mass. At the moment of protrusion the general health is not altered, but soon the inflammation and fever with the violent and continued straining induce ex
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nt, simple or associated with putrefaction of its liquid contents and general poisoning, or it may extend so that the inflammation affects the lining membrane of the whole abdominal cavit
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s, dullness, drowsiness, suspension of rumination and appetite, and a general indifference to surrounding objects. Soon the cow lies down, or falls and is unable to rise, but for one or t
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tained with such offensive products should be thoroughly washed. The general treatment of contagious mammitis does not differ from that of the simple form, except that antiseptics should
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septic germ and is associated with fetid discharge from the navel and general putrid blood poisoning. In estimating the causes of the disease we must not omit debility of the calf when th
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t the presence of some of the septic bacteria, and the results on the general system are a high fever and softening of the liver and spleen and no tendency to abscesses of the internal or
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n this way. The same may come from disease in the cow's udder, or any general disease of the cow with attendant fever, and in all such cases the tendency is to rapid change and unwholesom
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appears desirable to describe some of the characteristics of forms in general and of a few classes into which they may be divided, leaving the special study of individual bones to the ill
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is one in which other structures surrounding the bones are injured. GENERAL SYMPTOMS OF FRACTURE.--When a fracture of one or more of the large bones of a limb occurs, symptoms are sure
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side will be less prominent than the other. Careful manipulation will generally move the parts so that crepitus may be recognized. If the fracture is through the posterior part of the bon
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ed three or four times at intervals of three weeks. The lameness will generally begin to disappear about the third or fourth month if the above-described treatment proves beneficial. Shou
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ack may be used. Various types of dehorning shears or clippers are in general use. One type of dehorner has a stationary knife edge with its cutting edge shaped like a very wide V, and op
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fully dealt with under another heading. We would add, however, that, generally speaking, the animal, after being castrated, should either be regularly exercised or be allowed freedom so
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ions of the tumor by a pathologist will be found most satisfactory. GENERAL TREATMENT OF TUMORS. For benign tumors treatment is required only when it damages the animal's value or when
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By M. R. TRUMBOWER, D. V. S. [Revised by John R. Mohler, V. M. D.] GENERAL DISCUSSION. The skin consists of two parts--a superficial layer, the epidermis, or cuticle, and the deep, or
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lved. We must endeavor to remove the cause by giving attention to the general health of the animal and to its environment. Feeding should be moderate in quantity and not too stimulating i
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e spontaneously or follow a scar after an injury. _Symptoms._--Kelis generally appears below the knee or hock, and may occur singly or in numbers. There are no constitutional symptoms. I
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d for a little distance forward on its outward surface, the cornea is generally said to be fitted into the sclerotic like a watch glass into its rim. The venous canal of Schlemm runs circ
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r of refraction is lost--the animal can not see. _Causes._--Cataract generally arises from a diminution (atrophy) or other change in the nutrition of the lens; it may occur as a result o
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RFY EARS. Cattle are subject to scurfy ears, which may be owing to a generally morbid condition of the skin, or may be confined to the ears alone. The affected animal shows an inclinatio
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he usual manner, by an inflammation of the lungs and pleurÊ, which is generally extensive, and which has a tendency to invade portions of these organs not primarily affected and to cause
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ay bloat and later be affected with a severe diarrhea. Such cases are generally fatal in 7 to 20 days. Very often the attack comes on slowly and the symptoms are much less clear. In the
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. It is then a difficult undertaking, simply because the contagion is generally widely disseminated before any measures are adopted, and because a great majority of cattle owners will nev
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ot or ground itch of cattle, the inflammation of the skin and toes is general and not in certain spots, as in foot-and-mouth disease. The mouth remains unaffected, and the presence of the
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gives off the odor of rancid butter. The internal hemorrhages are not general, although they may occur. A microscopic examination of the juices from the tumefaction will show the blackleg
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animals or to damage the surroundings. The cow remains quiet and the general muscular contraction gives her a rigid appearance. There is an absence of paralysis which marks the advanced
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imals together, drafts of air which cause colds and catarrhs, and, in general, everything which prevents the animals from developing and maintaining the highest condition of health. None
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nd when the disease had yet made but little progress. It is now quite generally employed. The tuberculin test came into existence through the most careful and thorough scientific experim
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reameries, with the offal of the abattoirs, with the household refuse generally, and behind tuberculous cattle. If tuberculosis is common among cattle, it is likely to be transmitted to h
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tely fatal in cattle after eight to nine weeks; 4 likewise produced a generalized tuberculosis, but which certainly had a more chronic course, while 1 of the cultures caused only an infil
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fresh condition under a microscope magnifying up to 250 diameters the general structure is made out without much difficulty. These grains consist of collections of minute, roundish masses
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se. Actinomycosis is not infrequent in cattle in the Southwest and is generally supposed to be the result of eating the prickly fruit of the cactus plant, causing wounds of the mucous mem
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ys already described. If the disease begins in the skin, it agrees in general with the subacute form in prolonged duration, and it may occasionally terminate in recovery if the swellings
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_Symptoms and lesions._--The symptoms of blackleg may be either of a general or of a local nature, though more frequently of the latter. The general symptoms are very much like those bel
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of the multiplication of the bacilli at the point of inoculation. The general affection is an intoxication, or poisoning, of the whole system produced by a soluble toxin elaborated by the
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death, can be removed without pain to the animal. The intestines are generally normal, but, together with the peritoneum, they may be inflamed, and the lungs are usually the seat of an e
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d show very plainly. (Pl. XLVI, figs. 6 and 7.) _Prevention._--It is generally accepted that if southern cattle are entirely free from that species of tick known as _Margaropus annulatus
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apsed to leave no doubt that eradication has been accomplished. As a general rule it has been found that if dipping is begun in March and systematically and thoroughly done, all cattle b
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thereby retard the final recovery. Medical treatment of the sick has generally been unsatisfactory, although in chronic cases and those occurring late in the fall beneficial results have
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t damage the horn, and congregate there only to rest. In view of the general practice of dehorning cattle, the name hornfly is less distinctive than it once was. Moreover, hornflies rest
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sed that the ox warbles of this country were all of the one kind. The general appearance, life history, and effects of the European species are much the same as those of the American form
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gh this parasite has been accused of producing serious effects, it is generally considered harmless. Several species of roundworms may occur in the fourth stomach. Two of these are of sp
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of the animal may be comparatively good. It is rare that one sees a generalized edema in slaughtered cattle as a result of fluke invasion, and even in the heaviest infections of you
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iption, symptoms, and treatment, 464-469 dropsy-- general, cause and treatment, 180 of abdomen, description and treatment,
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bones, description and treatment, 277 general symptoms and treatment, 272, 273 hip point, causes and treatment,
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id, description and treatment, 350 general treatment, 309 kidney, description,
bands penetrating the lung tissue in all directions constitute the true
marbling according to other observers.
PLATE XXXII. Contagious pleuropneumonia. This illustrates what are called
infarctions. The right half of the figure shows nearly normal lung tissue.
The left represents a blackish mass, in which the lung tissue is filled
with blood and solidified. This is caused by the plugging of the vein
carrying away the blood from this portion. The heart forces the blood
through the artery into the tissue at considerable pressure, but owing to
the fact that its return is prevented, the minute blood vessels rupture and
the air vesicles become distended with blood, which coagulates and causes
the firmness of the tissue.
* * * * *
On the other hand, it is known that the serum from affected lungs retains
its virulence and may be used successfully for inoculation weeks or months
after the death of the animal from which it was taken. This is
particularly the case when this liquid is hermetically sealed in glass
tubes. Other investigators state that they have successfully infected
cattle by placing, in the nostrils, sponges or pledgets of cotton saturated
with such serum. Cattle have also, according to the best evidence
obtainable, been infected from the clothing of attendants, from horns used
in drenching, and from smelling about wagons which have been used to
transport affected carcasses. In the work of eradicating pleuropneumonia
from the United States many stables were found in which the disease would
appear and reappear after the slaughter of affected herds, and in spite of
any precautions which were adopted. These were always old stables, with
woodwork in a decaying condition and with floors underlaid with filth which
could not be thoroughly removed or disinfected. In every one of these cases
the destruction of the stable, the burning of the lumber of which it was
constructed, the removal of the accumulations beneath the floors, and
thorough disinfection, prevented the recurrence of the plague in new
stables built upon the same premises. This experience conclusively shows
that under certain conditions, at least, stables may retain the infection
for a considerable time, and that when restocked the disease may break out
again from such infection.
As a rule, however, the disease is acquired by a healthy animal being near
an affected one and receiving the contagion direct. Affected animals may
give off the contagion in the early stages of the disease before the
symptoms are apparent to the observer; also, they may retain this
infectious character, if they survive the attack, for six months and
probably for a year after all symptoms of the disease have disappeared.
_Incubation._--The time which elapses between exposure to the contagion of
pleuropneumonia and the first appearance of the symptoms of this disease
varies greatly with different individuals and with different outbreaks of
the disease. Ordinarily the symptoms of disease make their appearance
within three to six weeks after exposure; they may be observed, however,
within two weeks or they may not become apparent until nearly or quite
three months. It is this long period of incubation and the great length of
time that an animal may disseminate the contagion after apparent recovery
which give the plague that insidious character so often spoken of, and
which greatly increase the difficulties of eradication.
_Symptoms._--The symptoms are such as would be expected with inflammation
of the lungs and pleurÊ, but they vary considerably, according to the type
which the disease manifests. If the attack is an acute one, as is
frequently seen in hot weather, the symptoms appear suddenly; the breathing
becomes rapid and difficult, the animal grunts or moans with each
expiration, the shoulders stand out from the chest, the head is extended on
the neck, the back is arched, the temperature is 104∞ to 107∞ F., the milk
secretion is suspended, there is no appetite, rumination is stopped, the
animal may bloat and later be affected with a severe diarrhea. Such cases
are generally fatal in 7 to 20 days.
Very often the attack comes on slowly and the symptoms are much less clear.
In the mildest cases there is a cough for a week or two, but no appreciable
loss of appetite or elevation of temperature. The lungs are but slightly
affected and recovery soon follows. Such animals may disseminate the
contagion for a long time without being suspected, and for that reason are
the most dangerous of all.
A more severe type of the plague is the most frequently seen. In these
cases the cough is frequent, more or less painful, the back somewhat
arched, and the milk secretion diminished. The prominence of these symptoms
increases, the appetite is affected, the animal loses flesh, the breathing
becomes more rapid, the cough more painful, pressure of the fingers between
the ribs shows tenderness, the hair loses its gloss and stands erect, the
skin becomes adherent, little, if any, milk is secreted, and the
temperature rises, varying in different animals from 103∞ to 107∞ F.
Animals thus affected may continue to grow worse and die in from three to
eight weeks, or they may after a time begin to improve and make an apparent
recovery. The inflammation of the lung does not, as a rule, subside and the
organ return to its normal condition, as is the case in ordinary pneumonia,
but with this disease the life of the affected portion of the lung is
destroyed, the tissue dies, and a fibrous wall is formed around it to shut
it away from the living parts. The tissue, thus encysted, gradually
softens, becomes disintegrated, and breaks down into pus. The recovery,
therefore, is not complete; it is only apparent and partial.
To those accustomed to examining the lungs of cattle, other and extremely
important symptoms may be apparent during the course of the disease. By
applying the ear over the walls of the chest an area of a certain extent
may be found in which the natural breathing sound is diminished or entirely
lost. This represents the diseased portion of the lungs. In other cases a
loud blowing sound may be heard, quite different from any sound produced
when the lung is in a healthy condition. In some cases crepitation is heard
near the border line of the diseased area and friction sounds produced by
the roughened pleura; these can be appreciated, however, only by those
whose ears have been trained to distinguish between the different sounds
which reach the ear when applied to the chest wall. By percussion--that is,
by pressing the fingers of the left hand firmly against the wall of the
chest and tapping upon the middle finger with the ends of the fingers of
the right hand--an area of dullness may be discovered corresponding to the
portion from which the respiratory murmur has disappeared. This loss of
respiration detected by auscultation, and the dullness brought out by
percussion, are the most important evidences of an inflamed or consolidated
lung.
Seriously affected animals remain standing if they have sufficient
strength, but those which lie down always lie on the affected side.
The proportion of animals which become affected after being exposed varies
according to the virulence of the outbreak, the susceptibility of the
animals, and the length of time during which exposure is continued.
Sometimes not more than 15, 20, or 30 per cent will contract the disease
when a large herd is exposed; on the other hand, however, 80 or 90 per cent
may be affected. The proportion of cases in which the disease proves fatal
also varies greatly--it may not exceed 10 and it may reach 50 per cent. In
general, it may be said that about 40 per cent of the exposed animals will
contract the disease and about one-half of these cases will prove fatal.
_Post-mortem appearances._--Owing to the complexity of the structure of the
lung tissue, its ramifications of bronchial tubes and blood vessels, and
its abundant supply of lymphatics, the pathological changes in
pleuropneumonia are interpreted with great difficulty. Furthermore, there
are certain kinds of pneumonia which present some resemblances to
pleuropneumonia and which may therefore be confused with it in some of its
phases.
If we kill an animal affected with acute pleuropneumonia and examine the
cavity of the chest and lungs, the following appearances will be noted:
The thorax may contain more or less serum, which may be clear or clouded.
There may be firm adhesions of different parts of the lungs to the chest
wall, the extent of which depends on the stage and severity of the disease.
The diseased lobes are unusually large and exceedingly firm to the touch.
The weight of a single large lobe may reach 40 pounds. Usually only one
side is affected, often but a single lobe, and this most commonly the large
or principal lobe. The pleura may be covered with one or more layers of a
firm, elastic, grayish membrane, which varies in thickness and which
sometimes may be pulled away entirely. Sometimes it is absent. The pleura,
however, is opaque and apparently very much thickened. This is owing to the
diseased condition of the connective tissue beneath the pleura, as will be
explained later. When an affected lobe is cut through at right angles to
its long diameter, the cut surface presents a variety of interesting
changes. In the first place the spaces between the small subdivisions of
the lung (the lobules), which in the healthy lung are barely visible, are
distended with a yellowish-white, usually quite firm, substance, which is
coagulated fibrin. The cut surface thus appears divided into small fields
by yellowish-white bands of varying thickness running in various directions
through the lung tissue and beneath the pleura. (Pl. XXXI.) These bands may
appear honeycombed and the spaces filled with yellowish fluid (serum) or
they may be uniformly solid. It will also be noticed that the space
immediately outside of and around the artery, vein, and air tube is
similarly broadened by fibrinous deposits. Some authorities look upon these
bands as constituting the so-called "marbling" of pleuropneumonia.
In addition to these changes which have taken place in the connective
tissue between the lobules, the lung tissue itself may be markedly altered.
Certain areas of the cut surface may be very firm in texture and of a
brownish-red color. The cut surface is granular or roughened, not smooth to
the eye. Other areas equally firm may be more grayish yellow and still
others may be blackish. (Pl. XXXII.) Besides these areas which represent
solidified (hepatized) lung tissue there may be others which approach the
normal lung tissue in color, are soft, and float in water. From these a
milky, purulent fluid may often be expressed. These different shades are
represented in Plate XXXI, fig. 2, within a small compass. Some authorities
are inclined to consider these variations in color on the same cut surface
as the so-called marbling of pleuropneumonia. It matters not whether we
regard the bands between the lobules or the varying shades of the lobules
themselves as the marbling, provided either or both are peculiar to
contagious pleuropneumonia. If we examine the blood vessels appearing on
such cut surface they will usually be found plugged within the firmly
hepatized regions. The artery contains a dark, soft, removable clot, the
vein a grayish-pink, granular, fragile plug (thrombus), which adheres
firmly to the wall of the vein, and if this is slit open, indications of a
diseased condition of the inner coat will be readily detected. When large
regions of the lung tissues are hepatized, the main air tube and its
branches are usually filled with grayish, cylindrical branched masses of
fibrin that are easily removed, as they do not adhere to the mucous
membrane.
The views of pathologists differ as to the nature of the earliest changes
in pleuropneumonia, and it is not within the scope of this work to present
controverted or imperfectly developed theories. In the foregoing
description we have taken as a type the acute pleuropneumonia in its fully
developed phase, which can scarcely be mistaken for any other disease. We
have seen that there is an inflammatory condition of the connective tissue
between the lobules, resulting in the exudation of coagulable lymph. This
inflammation is equally marked around the blood vessels and air tubes. It
leads to inflammatory changes in the inner wall of the veins, and these
cause the deposition of thrombi or plugs in the vessels, which prevent the
return of the blood. The blood pumped into the lung tissue through the
artery, but unable to get out by way of the vein, leaves the mesh-work of
capillaries around the air vesicles, enters the latter, and produces the
firm, hepatized condition so characteristic of this disease. If we bear in
mind that the veins in different parts of the lung tissue are plugged at
different times, and that, therefore, the affected regions are in different
stages of disease, it will be easily understood how the different shades of
color from dark red to grayish or yellowish red are produced.
The complete plugging of the veins may lead to the death of circumscribed
masses of lung tissue. A line of separation forms between the living and
the dead tissue and a thick cyst wall of fibrous tissue forms around the
latter. The dead tissue for a time preserves the appearance of lung tissue,
then undergoes disintegration and liquefaction. The softened mass is
finally absorbed, and the walls of the cyst, or capsule around it,
gradually collapse and form a cicatrix. This favorable termination takes
place only when the dead mass is not too large. It may, however, involve
over half of one of the large lobes. Under such circumstances recovery is
improbable. A more favorable termination is the abundant growth of fibrous
tissue around and into the hepatized masses. The formation of fibrous
tissue may extend to the pleura, or lung covering, and cause firm adhesion
of the lungs to the chest wall and to the pericardium, or heart case.
The same peculiar, inflammatory changes which take place between the
lobules of the lung and around the bronchi and vessels may invade the
pleural cavity, cause extensive membranous and spongy deposits on the
pleura and firm deposits around the heart and large arteries, the gullet,
and windpipe.
These are the main features of the lung disease caused by contagious
pleuropneumonia. In the typical, acute cases there are a sufficient
number of peculiarities to enable us to make a positive diagnosis. There
are, however, many cases in which the disease is restricted to small areas,
or to the interlobular tissue, or in which the changes are still
imperfectly developed, or else so far advanced that doubts may arise as to
the true nature of the affection. In such cases all obtainable facts,
including the history of the case, the symptoms during life, and the
pathological changes observed on post-mortem examination must be taken into
consideration. Only one who has made a careful study of the disease is
fitted to decide in such cases.
Other kinds of lung disease, because of certain features common to most
lung diseases of cattle, may be confounded with pleuropneumonia. The
inflammation of the connective tissue between the lobules is not
infrequently observed in so-called interstitial pneumonia and may lead to
the formation of whitish bands intersecting the lung tissues in various
directions. On the cut surface these bands may give rise to a decidedly
marbled appearance. Again, in traumatic pneumonia, caused, as its name
implies, by the entrance of foreign bodies into the lung tissue, generally
from the paunch, the connective tissue around the place of disease becomes
inflamed and thickened, and the disease itself may simulate pleuropneumonia
in its retrogressive stages when it is confined to a small portion of lung
tissue. The filling up of the interlobular spaces with fibrin and
connective tissue of inflammatory origin is not thus limited to
pleuropneumonia, but may appear in a marked degree in other lung diseases.
It must not be inferred from this statement that these interlobular changes
are necessarily the same as those in pleuropneumonia, although to the naked
eye they may appear the same. We simply note their presence without
discussing their nature.
In general, the distinction between pleuropneumonia and bronchopneumonia is
not difficult to make. In the latter disease the pneumonia generally
invades certain lobes. The disease attacks the smaller lobes in their
lowest portions first and gradually extends upward, i. e., toward the root
of the lung or the back of the animal and backward into the large principal
lobes. Again, both lungs in advanced cases are often symmetrically
affected. In contagious pleuropneumonia the large principal lobe of one
side is most frequently affected, and a symmetrical disease of both lungs
is very rare, if, in fact, it has ever been observed. The lung tissue in
bronchopneumonia is not enlarged, but rather more contracted than the
normal tissue around it. This is well illustrated in Plate XXX. Normal,
air-containing lobules may be scattered among and around the hepatized
portion in an irregular manner. In pleuropneumonia the diseased and healthy
portions are either sharply divided off, one from the other, or else they
shade into each other by intermediate stages.
The hepatized lung tissue in bronchopneumonia when the cut surface is
examined is visually of a more or less dark flesh color with paler
grayish-yellow dots regularly interspersed, giving it a peculiar, mottled
appearance. In the more advanced stages it becomes more firm, and may
contain nodular and firmer masses disseminated through it. The air tubes
usually contain more or less soft, creamy, or cheesy pus or a turbid fluid
quite different from the loose, fibrinous casts of acute pleuropneumonia.
The interlobular tissue may or may not be affected. It sometimes contains
loose, fibrinous plugs, or it may be greatly distended with air, especially
in the still normal portions of the lung. The pleura is seldom seriously
diseased. If we contrast with these features the firm dark-red
hepatizations, the plugging of the veins, the extensive interlobular
deposits, and the well-marked pleuritis in pleuropneumonia, there is little
chance for confusion between well-developed cases of these two lung
diseases.
It should not be forgotten, however, that the lesions of the disease known
as contagious pleuropneumonia may be confined to the serous membranes of
the thorax, or they may be confined to the parenchyma of the lungs; they
may affect a whole lobe, or only a small portion of it; they may or may not
cause the so-called marbled appearance. In the same way bronchopneumonia
may vary as to the parts of the lung affected, the extent of the lesions,
the degree and kind of pathological changes in the interlobular tissue, the
color of the lung on cross section and the amount of hepatization. In
individual cases, therefore, it is often necessary to take into account the
history of the animal, the course of the disease, and the communicability
of the affection before a diagnosis can be made between the two diseases.
_Prevention and treatment._--The prevention of pleuropneumonia, as of other
contagious diseases, consists in keeping animals so that they will not be
exposed to the contagion. As the disease arises only by contagion, there is
no possibility of an animal becoming affected with it unless it has been
exposed. If, therefore, pleuropneumonia exists in a locality the owner of
healthy cattle should make every effort to keep his animals from coming
near affected ones or which have been exposed. He should be equally
particular not to allow persons who have been on the infected premises to
visit his own pastures, stables, or cattle.
If pleuropneumonia breaks out in a herd, every animal in it should be
SOURCES & PROVENANCE
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