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Special report on diseases of cattle and on cattle feeding online

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or the sponges used in cleaning the diseased may carry the virus to
the healthy.

Symptoms. The period elapsing between the infection and the appear-
ance of symptoms is somewhat variable. It is usually given as three to
six days. It juay be briefer or much longer. In cows the mucous mem-
brane of the vagina and the vulva become swollen, reddened, and very
tender. The secretion is very abundant and consists at first largely of
serum and mucus. Small vesicles then appear which rapidly burst and
are converted into excoriations or deeper ulcerations. The secretion
becomes more purulent, and is apt to dry in crusts about the root of the
tail. The eruption in accompanied with much itching and difficulty in
urinating. The walk may be stiff' and awkward. In bulls the eruption
is situated on the prepuce and the end of the penis, and is accompanied
by a little purulent discharge from the prepuce, itching and difficulty
in urinating. In severe cases the inflammation and swelling may extend
backward to the scrotum and forward upon the abdomen.

The disease lasts from two to four weeks, and always terminates in
recovery. The acute stage lasts only four or live days, while the com-
plete healing of the inflammation is slow. The eruption is usually ae-
companied by very little general disturbance. If the pain and irrita-
tion are severe there may be some slight loss of appetite and diminished
milk secretion.

Treatment need not be resorted to excepting in severe eases. The
secretion and exudation should be washed oft' anil a mild antiseptic
applied, such as a 1 per cent solution of carbolic acid (I ounce to 3



396 DISEASES OF CATTLE.

quarts of water). Care must be taken not to carry the disease from
the sick to the well by sponges, etc., which have come in contact with
the affected organs. These should be destroyed. To prevent the spread
of the disease the infected animals should be kept isolated until they
have recovered.

BABIES OR HYDROPHOBIA.

Babies is a disease which seems to originate in the canine race and
which may be transmitted to other species of animals and to man
through bites. There are some writers who maintain that it may arise
spontaneously in the dog without previous inoculation. The advances
made in our knowledge by the researches of Pasteur and others do not
favor this view, but lead directly to the inference that rabies is always
communicated from a preceding case, and that it never originates spon-
taneously.

We must assume, therefore, that the disease is always transmitted
by the bite of the rabid animal. The saliva contains the virus which
is introduced into or under the skin on the tooth of the rabid animal.

By no means are all bites followed by rabies. According to some
authorities only one-fourth of the inoculated cattle become diseased.
This low percentage may be due to the kind of wound inflicted. When
the bleeding is very profuse the virus may be washed out at once. As
to the nature of this virus nothing is definitely known, although Pas-
teur and his co-workers have made prolonged efforts in this direction.

In general the virus behaves like bacterial poisons. It may be trans-
mitted from one animal to another by simple inoculation, just as we
may preserve the virus of other infectious diseases.

From these facts it becomes evident that the virus of rabies can only
be transmitted directly from the sick to the healthy, and that for this
transmission a wound is necessary. Since the virus is contained in the
saliva, the disease may be artificially produced by inoculating an animal
with the saliva of some rabid animal. Healthy animals, from the nature
of the case, can not carry the virus. It is still a widely prevalent belief
that if persons or animals are bitten by a dog,' for instance, they are
liable to become rabid when such a dog contracts rabies at any time in
the future. There is no foundation for such belief, and it would be a
great comfort to many people who are now and then bitten by animals
if such belief were given up. There is no foundation for the theory
that rabies may be caused by the bite of an animal which has been
inoculated, but in which the disease has not yet appeared. All exper-
ience, both scientific and practical, goes to show that rabies is trans-
mitted only by animals actually diseased.

Babies is not a very uncommon disease in cattle in those regions
where rabid dogs are occasionally found. Thus in the German Empire
carefully compiled statistics have shown that next to dogs cattle are
more frequently affected than any other of the domesticated animals.



INFECTIOUS DISEASES OF CATTLE. 397

In 1890 590 dogs, 98 head of cattle, 11 cats, and 9 pigs were found
rabid. These figures are easily explained when we take into considera-
tion the relation between dogs and cattle. The latter are very much
exposed to the bites of the former on pastures. It is also well known
that dogs are more or less trained and incited to worry cattle at all
times. The latter receive bites most frequently on the hind legs and in
the hips and about the lower jaw. These places are most accessible to
dogs, owing to the habit of cattle to drive their tormentors away by
lowering their head and using their horns.

The virus after being deposited in the wound by the bite of a rabid
animal, remains latent for a time. This period of incubation is quite
variable in duration. One veterinarian (Gerlach) collected the statis-
tics of 133 cases, and found this period to vary from 14 to 285 days.
The majority of cases, however, contract the disease in from one to three
months after the bite has been inflicted.

Symptoms. The disease may be divided into a preliminary stage, a
stage of excitation or madness, and a paralytic stage. In all cases the
termination is fatal and the-cntire course is from 5 to G days. The pre-
liminary stage is indicated by loss of appetite and rumination, great
restlessness, anxiety, and manifestation of fear. The second stage is
characterized by increasing restlessness, loud roaring at times with
changed voice, violent butting with the horns and pawing the ground
with the feet. A constant symptom is the increased secretion of saliva
which hangs from the mouth in strings, and which may be frothy. Con-
stipation is marked, and there is manifested a continual effort to
defecate, which is unsuccessful. Spasms of the muscles in different
parts of the body are also present at intervals.

In the final stage symptons of paralysis appear, especially in the
posterior limbs, and the walk becomes stiff, unsteady, and swaying.
Complete paralysis of the posterior half of the body may appear be-
fore death. In this final stage the body is very much emaciated, in
spite of the brief duration of the disease. It should also be stated that
there in no fever or elevation of temperature during the disease. If
cattle which have succumbed to rabies be opened very slight evidence
of disease will be found anywhere. The blood is dark and imperfectly
coagulated. The throat may be reddened and there may be small spots
of extra vasated blood in the intestines. The stomachs arc usually empty.
In the spleen there may be hemorrhagie enlargements (infarcts). The
cadavers rapidly undergo decomposition.

It is not an easy matter to decide whether a given animal has rabies,
since the symptons and the lesions given al>ove belong in part to a
variety of other diseases. The positive evidence that a rabid dog has
been near cattle would greatly assist in making a decision in doubtful
cases. The disease in dogs is pretty well recognized by most people,
but. in case a suspected dog is killed it is desirable to open the animal
and examine the contents of the stomach. While food is absent a



398 DISEASES OF CATTLE.

variety of odd things may be present which the abnormally changed
appetite of the rabid dog has induced him to swallow. Among such
things may be straws, sticks, glass, rags, earth, pieces of leather and
whatever the animal may have encountered small enough tobe swallowed.
This miscellaneous collection in the stomach of dogs is regarded by au-
thorities as a very valuable sign, and may be made use of by laj'mau in
case of doubt.

Treatment is out of the question after the symptoms have once ap-
peared. When, however, soon after a bite has been inflicted by a
rabid dog, the wound can be found it may be desirable to cauterize it
with the hot iron or with strong acids, alkalies, or even to cut out the
entire wound if such procedure is possible. Prevention which seeks to
control effectively the disease by restricting it among dogs is most
likely to prove successful. The measures which are adapted to this end
can not be discussed in this place.

The method of preventive inoculation which Pasteur has originated
and which seems to be so successful in the human subject is not appli-
cable to animals for various reasons.

TUBERCULOSIS.*

(Plates xxix, Fig. 6; xxxiv to xxxvm, inclusive.)

Tuberculosis is an infectious disease characterized by the formation
in various organs of the body of minute nodules or tubercles which con-
tain the bacillus tuberculosis, the cause of the disease.

The disease, in its various manifestations, has been known for many
centuries, and legislative enactments having reference to the destruc-
tion of affected animals and forbidding the use of the flesh date far back
into the Middle Ages. The opinions entertained regarding the nature
and the cause of the malady varied much in different periods, and very
markedly influenced the laws and regulations in vogue. Thus, in the
sixteenth century, the disease was considered identical with syphilis in
lhan. In consequence of this belief very stringent laws were enacted,
which made the destruction of tuberculous cattle compulsory. In the
eighteenth century this erroneous conception of the nature of the dis-
ease was abandoned and all restrictions against the use of meat were
removed. Since that time, however, the tide of opinion has again
turned against this disease. The particular opinion held at any time
concerning its nature usually furnished for it a name. There are in
most languages, therefore, a large number of peculiar terms which have
accumulated, but which do not concern us here.

Occurrence. The statistics concerning tuberculosis show that it is a
disease prevalent in all civilized countries. In some countries, such as
the northern part of Norway and Sweden, on the steppes of eastern

* For a brief account of the disease iu other auiuials, see the Report of the Secretary
of Agriculture for 1889, p. 63.



INFECTIOUS DISEASES OF CATTLE. 399

Europe ami Russia, in Sicily and Iceland, and in Algiers it is said to
be quite rare. In most countries an effort is now being made to deter-
mine more accurately the prevalence of this disease. Some very valu-
able tables have been published by the German Government for the
year extending from October, 1888, to October, 1889. We learn from
this that of 1,270,004 animals killed for beef in public abattoirs 26,332,
or about 2 per cent, were tuberculous.

In France, according to figures given by Arloing, there are, on the
average, 5 animals tuberculous in every 1,000, or about one-half per cent.
In the various cities of France the figures obtained by inspectors at the
abattoirs vary from 1.43 to 14.5 per 1,000, the observation extending
over a period of one to five years. In Belgium, according to Van Hert-
sen, the rate is 4 per cent. In Holland it varies from 4 to 19.6 per
1,000. In England, according to Cope, it varies from 1 to 26 per cent,
according to the locality. At Copenhagen, according to Bang, during
1888, the rate was 6 per cent; for cows alone it rose to 16 per cent. In
the Argentine Republic, according to Even, tuberculosis seems to attack
the recently imported improved stock (10 to 15 per cent), while it is
comparatively rare among natives (one-half per cent).

In our own country cattle (mostly milch cows) slaughtered at Balti-
more under the auspices of this Bureau several years ago were found
tuberculous to the extent of 24 to 3 per cent. Among 2,273,547 head
of cattle, chiefly steers, slaughtered for beef in the various meat in-
spection districts of the United States from May 15, 1891, to March 1,
1892, only 492 or .02 per cent were found tuberculous. For the year
ending December 31, 1889, there were found in the same districts among
54,158 cows 669 cases of tuberculosis, or 1.23 per cent.

It is not far from the truth to assume from these statistics that one
of every fifty head of cattle in the more densely populated areas of
Europe and America is tuberculous. When we consider the age and
sex of the affected animals some striking differences are observed.
According to the German report the statistics of a large number of
abattoirs showed that 0.9 per cent of the cows, 3.6 per cent of the oxen,
2.6 per cent of the bulls, and not quite 1 per cent of the calves and
yearlings were tuberculous. It has also been observed that tuberculosis
increases in frequency with the age of the animals. If we take the
number of cases of animals of a year and under affected with tubercu-
losis as the unit of comparison, animals from one to three years old
furnish ten times, those three to six years old thirty times, and those
over six years forty times the number of cases.

The cause of this disease may be considered as twofold, the tubercle
bacillus first and foremost, without which this disease could never
develop, and en-tain predisposing causes which prepare the way for it.
First, as to the way sin which tubercle bacilli find their way into the body.
These in the order of their importance may be considered under four
heads: (1) By inhalation into the lungs; (2) into the digestive tract in



400 DISEASES OF CATTLE.

the milk of tuberculous cows ; (3) during coition when the sexual organs
are tuberculous ; (4) from the tuberculous mother to the fetus in the
uterus. Inhalation is by far the most common mode of infection, since
statistics show a large percentage of primary lung disease in cattle.
Thus in the German report quoted the lungs were found 14.J times more
frequently diseased than the digestive organs.

The bacilli can only get into the lungs when inhaled. They must,
therefore, be thoroughly dried and pulverized before currents of air can
carry them. It is well known that the bacilli withstand drying for
months before they lose their power of producing disease. They leave
the body of diseased animals in several ways. There may be a little
discharge occasionally coughed up from the diseased lungs, or milk may
be spilt, or there may be a discharge from the vagina when the genital
organs are tuberculous. The bacilli from these sources may become
dried and pulverized, and carried in the air of the stable and into the
lungs of still healthy cattle where the disease then develops.

The disease of the stomach, intestines, and meseuteric glands is very
probably the result of food infection. Tubercle bacilli may have been
scattered upon the feed by diseased animals. But the most common
source of such infection is the milk of tuberculous cows. Calves may
become infected in this way. The disease may remain latent until the
animal becomes older. The not infrequent occurrence of tuberculosis
of the uterus and ovaries makes it probable that the disease may be
transmitted by a diseased bull, or carried by a healthy bull from a dis-
eased cow to a number of healthy cows.

The source of infection is always some previous case of the disease, for
the latter can never arise spontaneously. Hence, in those stables in
which there is frequent change of cattle, the introduction of tuberculo-
sis by cattle coming from other infected stables is the most frequent
source of infection. Since the bacilli, when dried, can be carried by the
air it is not necessary that healthy animals should come in direct con-
tact with cases of disease to become infected.

We Avill now briefly consider the various conditions which favor the
bacilli in their attack. Unsanitary conditions, such as overcrowding
in poorly- ventilated and poorly-lighted stables, and feeding of food
which is not nutritious, are not insignificant in this respect. Condi-
tions which injure the lungs are favorable to the development of tuber-
culosis. Among these are the inhalation of dust and smoke, and all
conditions which may induce chronic inflammation of the bronchial
tubes, with abundant secretion and subsequent pneumonia (broncho-
pneumonia). Among the other causes which are said to favor tuber-
culosis is the overproduction of milk, too many births, the improvement
of stock by continual inbreeding, and the consequent inheritance of
certain constitutional characters of a debilitating nature. Animals
living in the lowlands are more subject to this disease than the more
robust races living in elevated mountain regions. Similarly, animals



INFECTIOUS DISEASES OF CATTLE. 401

on the open pasture are less susceptible than stabled animals. This
may. however, be due to concentration of virus in the stables. The dis-
ease is likewise far more common in cows than in oxen, owing to the
strain to which bringing forth young and milking subject the females.
Animals subjected to special feeding, such as cows in distilleries, brew-
eries, and other manufactories having waste available as food, are the
most susceptible to the disease. In general the greatest number of
cases occur in the immediate environment of cities where there are not
only abundant opportunities for infection, owing to the frequent intro-
duction of new animals into herds, but where the sanitary conditions
may be regarded as the poorest.

Nature of the disease. The bacillus of tuberculosis was discovered by
Robert Koch in 1882. It (see Plate xxix Fig. 6) is a slender rod-like
body from one- third to two-thirds the diameter of a red-blood corpuscle
in length. When the bacillus has become lodged in any organ or tis-
sue it begins to multiply, and thereby causes an irritation in the tissue
around it which leads to the formation of the so-called tubercle, whence
the general name of .the disease tuberculosis. The tubercle, when it
has reached its full growth is a little nodule about the size of a millet
seed. It is composed of several kinds of tissue cells. Soon a change
takes place within the tubercle. Disintegration begins, and a soft,
cheesy substance is formed in the center which may contain particles
of lime salts. When these tubercles continue to form in large numbers
they run together, forming masses of various size. The disintegration
whirh attacks them leads to the formation of large cheesy masses of a
yellowish color, containing more or less of lime salts in the form of
gritty particles. These large, tuberculous masses are surrounded by
or imbedded in layers of fibrous tissue which in some cases becomes
very dense and thick.

The disease is thus a development of these tubercles in one or more
organs of the body. The distribution and number of these determine
the course of the disease.

In a large number of cases the changes are limited to the lungs ai:d
the serous membranes * of the thorax and abdomen. Pathologists hav^
been in the habit of calling the lung disease tuberculosis and the <lis
ease of the serous membranes "pearly disease." Statistics have shown
that in about one-half the cases both lungs and serous membranes
;m> ili-cased, in one-third only the lungs, and in oiie-fifth only the
serous membranes. At the same time the lymphatic glands near tin-
<li- MS( (1 organs are usually involved. Other organs, such as the liver.
not infrequently contain tubercles. Though the disease may remain
restricted to a single organ, it now and then is found generalized, affect-
ing all organs of the body.

"These comprise the smooth, very delicate, glistening lining of the large body
cavities. In the thorax thepcrous membrane (plcnrn) covers the ribs and diaphragm
as well a* the whole lung surface. In tho abdomen a similar membrane (perito-
neum) lines tin- interior of the cavity and cover* the bowels, liver, spleen, etc.
24697 L'O



402 DISEASES OF CATTLE.

In the lungs (Plate XXXIY) the changes observed vary according to the
ago and intensity of the disease process. They usually begin with the
appearance of very minute tubercles. These may appear in large num-
bers on the surface of the lungs or within the lung tissue. Later the
contents become cheesy and partly calcined. When these tubercles
are sufficiently numerous to become confluent large masses may be
formed, which undergo the same retrogressive changes of caseation
and calcification. In addition to the formation of tubercles in the luug
tissue certain other changes take place. There is usually present- bron-
chitis with abundant catarrhal secretion. This plugs up the smaller
air-tubes, and the lung tissue supplied by these tubes with air collapses.
Subsequently it becomes filled with yellowish, cheesy matter, which
greatly distends the small air-tubes and air vesicles (broncho-pneu-
nionia). The connective tissue between the lung lobules, around the
tubercles and around the air tubes, becomes thickened and indurated.
In the larynx and the bronchi tubercles may vegetate upon the mucous
membrane, and ulcers may result from their breaking down. The in-
flammatory irritation which the growth of the tubercles on the sur-
face of the lungs arouses gives rise to adhesion of the lungs to the
ribs and diaphragm. This adhesion is sometimes so firm and extensive
that the lungs appear grown to the chest wall.

When, therefore, the lungs in advanced stages of the disease are cut
open we observe large yellowish masses, from one-quarter to three-
quarters of an inch in diameter, of a cheesy texture, in which calcified,
gritty particles are embedded and which are surrounded by very firm
connective tissue. The neighboring lung tissue, when collapsed and
involved in broncho-pneumonia, has the color and consistency of pale
red flesh. The air-tubes, large and small, stand out prominently 011
the cut surface. They are distended with a pasty, yellowish, cheesy
mass, surrounded and enveloped in thick mucus, and their walls greatly
thickened. The larger bronchi may be sacculated, owing to the dis-
tension produced by the cheesy contents.

The disease usually attacks the bronchial glands, which are situated
on the trachea and bronchial tubes at the bifurcation. The changes in
the glands are the same as those going on in the lung tissue, and they
frequently reach an enormous size.

The tubercle formation on the serous membranes covering the lungs
and chest wall, which may go on at the same time with the lung disease
or independent of it, has been called "pearly disease,'' on account of
the peculiar appearance of the tubercles. These begin as very minute
grayish nodules, which give the originally smooth, lustrous membrane
a roughened appearance. These minute tubercles enlarge, become con-
fluent, and project above the surface -of the membrane as wart-like
masses, attaining the size of peas. In this stage their attachment to
the membrane is by means of delicate fibers. The attachment is loose,
so that the tubercle hangs by a short pedicle or neck and may be
moved slightly to and fro. Large masses are frequently formed by a



INFECTIOUS DISEASES OF CATTLE. 403

coalescence of many tubercles and the secondary formation of the same.
These may be found on the lungs, the ribs, and the diaphragm. These
tubercles likewise undergo degenerative changes. The center partly
soft ens, partly calcines into a grayish mortar-like mass, and when cut into
they are found to be gritty. Associated with the formation of tubercles
on the pleura, those glands situated back of the lungs (posterior medias-
tinal) become greatly enlarged and the center cheesy. (Plate xxxvi.)
They may compress the esophagus and interfere with swallowing.
The size attained by these tumors and new growths is well illustrated
by the fact that, taken together, they not infrequently weigh from GO to
80 pounds. The bronchial glands, which in the healthy state are not
a< large as horse-chestnuts, have been found to attain a weight of over
10 pounds.

In the abdominal cavity tubercles may be found, both in the organs
and on the serous membranes covering them. They are situated pref-
erably on the oinentum or caul (see Plates xxxvn, XXXYIII, Fig. 2), the
diaphragm, and the walls of the abdomen. In the liver large and small
tubercular masses are occasionally encountered. (See Plate xxxv.)
The mesenteric glands (see Plate xxxvni, Fig. 1) are occasionally en-
larged and tuberculous; likewise the glands near the liver. Tubercles



Online LibraryUnited States. Bureau of Animal IndustrySpecial report on diseases of cattle and on cattle feeding → online text (page 46 of 56)